Co-reporter:Daniel Kessler, Florian D. Jochum, Jiyeon Choi, Kookheon Char, and Patrick Theato
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 2) pp:124
Publication Date(Web):January 4, 2011
DOI:10.1021/am1010892
Reactive surface coatings were used as an ideal precursor coating for the fabrication of three different photoswitchable surface coatings in parallel. Different light-responsive moieties, such as azobenzene, salicylideneaniline, and spiropyran, were immobilized on glass, polycarbonate, and steel surfaces. Independent from the underlying substrate, wettability could be switched reversibly by UV irradiation. The maximum switching range was obtained after functionalization of the reactive coating with spiropyran, resulting in a contact angle difference between the two isomeric states of almost 30°.Keywords (keywords): activated ester; azobenzene; light-responsive surface; salicylideneaniline; spiropyran; surface wettability
Co-reporter:Katja Nilles and Patrick Theato
Polymer Chemistry 2011 vol. 2(Issue 2) pp:376-384
Publication Date(Web):15 Oct 2010
DOI:10.1039/C0PY00261E
Homopolymers containing sulfonic ester side groups were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization utilizing benzyl dithiobenzoate, cumyl dithiobenzoate, and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid as chain transfer agents. Likewise diblock copolymers containing poly(styrene), poly(octylstyrene) and poly(pentafluorostyrene) as the second block were synthesized. Additionally, nitroxide mediated polymerization (NMP) was investigated for the synthesis of a homopolymer as well as for a diblock copolymer. Furthermore, the post-polymerization functionalization with various amines to yield the respective sulfonamides was conducted. The conversion was analyzed by 1H NMR spectroscopy, 19F NMR spectroscopy and FT-IR spectroscopy and in many cases a very high conversion (>96%) was observed. In addition the reaction kinetics of the post-polymerization functionalization of poly(pentafluorophenyl 4-vinylbenzene sulfonate) and the corresponding carboxyl ester poly(pentafluorophenyl 4-vinylbenzoate) were compared by analysis of the reactions by time-resolved 19F NMR spectroscopy. It was found that poly(pentafluorophenyl 4-vinylbenzoate) showed a higher stability towards hydrolysis and a significantly higher reactivity, resulting in complete conversions with different amines.
Co-reporter:Niko Haberkorn, Katja Nilles, Philipp Schattling and Patrick Theato
Polymer Chemistry 2011 vol. 2(Issue 3) pp:645-650
Publication Date(Web):10 Nov 2010
DOI:10.1039/C0PY00314J
A new route for the fabrication of polymeric nanorods with functional moieties via post-modification of reactive nanorods is described. To this end reactive nanorods with a homogenous and narrow size distribution were fabricated by utilizing an anodic aluminium oxide (AAO) template-assisted approach. The nanorods are based on activated pentafluorophenyl esters, to enable quantitative post-modification with amines under very mild reaction conditions yielding the corresponding functionalized amide. Post-modification with fluorescent dyes as well as the conversion into well-dispersed rod-shaped poly(N-isopropylacrylamide) (PNIPAM) hydrogels that exhibit a thermal-responsive phase transition was demonstrated. The platform of reactive nanorods provides the fabrication of various functional nanoobjects and may find application in research fields like drug delivery.
Co-reporter:Peter J. Roth, Florian D. Jochum and Patrick Theato
Soft Matter 2011 vol. 7(Issue 6) pp:2484-2492
Publication Date(Web):11 Feb 2011
DOI:10.1039/C0SM01324B
Poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) is shown to possess insoluble–soluble transitions (UCST-type phase behavior) in a large variety of aliphatic alcohols. Samples of different molecular weights ranging from 5 kg mol−1 to 23 kg mol−1 prepared by the RAFT process and featuring different end groups at each end were analyzed by cloud point measurements. Transitions occurred sharply and were fully reversible. The UCST was found to increase with an increasing molecular weight. Hydrophobic (alkyl chain) end groups were found to lower the critical temperature in isopropanol, while rigid aromatic end groups raised the transition temperature. In ternary mixtures of isopropanol/chloroform/POEGMA, the UCST decreased with an increasing chloroform concentration, with 10 vol% of chloroform accounting for a 30 °C drop. In mixtures of isopropanol/hexane/POEGMA, the cloud point increased significantly only with hexane concentrations above 30 vol%, at which level a 2 °C transition temperature increase was found. Addition of water to isopropanol solutions had a strong effect, with 1 vol% of water causing a decrease of the transition temperature of 12.5 °C. With an increasing chain length of the solvent, the cloud point increased, while a branching of the hydrocarbon chains lowered the cloud point. Samples of 23 kg mol−1POEGMA were for instance found to have cloud points of 22.0 °C in ethanol, 35.7 °C in isopentanol, and 75.4 °C in dodecanol.
Co-reporter:Anja C. Pauly
Journal of Polymer Science Part A: Polymer Chemistry 2011 Volume 49( Issue 1) pp:211-224
Publication Date(Web):
DOI:10.1002/pola.24442
Abstract
Four monomers based on 4-ethynylbenzoic acid have been synthesized, one of those featuring an activated ester. With the metathesis catalytic system WCl6/Ph4Sn, these acetylenic monomers could successfully be polymerized yielding conjugated polymers with molecular weights of around 10,000 to 15,000 g/mol and molecular weight distributions Mw/Mn ≤ 2.1. Also the copolymerization of phenylacetylene or methyl 4-ethynylbenzoate with pentafluorophenyl 4-ethynylbenzoate as reactive unit was conducted. Polymer analogous reactions of the reactive polymers and copolymers with amines have been investigated and it was found that poly(pentafluorophenyl 4-ethynylbenzoate) featured a significant reactivity, such that reactions proceeded quantitatively even with aromatic amines. Moreover the UV-Vis spectra of the activated ester based polymer before and after conversion with aliphatic amines showed a change, indicating an effect on the conjugated backbone of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Co-reporter:Florian D. Jochum and Patrick Theato
Chemical Communications 2010 vol. 46(Issue 36) pp:6717-6719
Publication Date(Web):17 Aug 2010
DOI:10.1039/C0CC01288B
In this communication, the synthesis and characterization of thermo- and light responsive block copolymers is reported. PEO-b-PNIPAM polymers with azobenzene moieties were prepared and analyzed by turbidimetry, fluorescence, NMR and DLS measurements. A temperature controlled reversible formation as well as a light induced disruption and reformation of micellar structures in water was found.
Co-reporter:Niko Haberkorn, Stefan A. L. Weber, Rüdiger Berger and Patrick Theato
ACS Applied Materials & Interfaces 2010 Volume 2(Issue 6) pp:1573
Publication Date(Web):May 3, 2010
DOI:10.1021/am100085t
We describe the synthesis and characterization of a cross-linkable siloxane-derivatized tetraphenylbenzidine (DTMS-TPD), which was used for the fabrication of semiconducting highly ordered nanorod arrays on conductive indium tin oxide or Pt-coated substrates. The stepwise process allow fabricating of macroscopic areas of well-ordered free-standing nanorod arrays, which feature a high resistance against organic solvents, semiconducting properties and a good adhesion to the substrate. Thin films of the TPD derivate with good hole-conducting properties could be prepared by cross-linking and covalently attaching to hydroxylated substrates utilizing an initiator-free thermal curing at 160 °C. The nanorod arrays composed of cross-linked DTMS-TPD were fabricated by an anodic aluminum oxide (AAO) template approach. Furthermore, the nanorod arrays were investigated by a recently introduced method allowing to probe local conductivity on fragile structures. It revealed that more than 98% of the nanorods exhibit electrical conductance and consequently feature a good electrical contact to the substrate. The prepared nanorod arrays have the potential to find application in the fabrication of multilayered device architectures for building well-ordered bulk-heterojunction solar cells.Keywords: anodic aluminum oxide (AAO); conductive scanning force microscopy; nanorod arrays; organic photovoltaics; tetraphenylbenzidine
Co-reporter:Krishna C. Etika;Florian D. Jochum;Michael A. Cox;Philipp Schattling;Jaime C. Grunlan
Macromolecular Rapid Communications 2010 Volume 31( Issue 15) pp:1368-1372
Publication Date(Web):
DOI:10.1002/marc.201000170
Co-reporter:Florian D. Jochum;F. Romina Forst
Macromolecular Rapid Communications 2010 Volume 31( Issue 16) pp:1456-1461
Publication Date(Web):
DOI:10.1002/marc.201000146
Co-reporter:Peter J. Roth, Florian D. Jochum, F. Romina Forst, Rudolf Zentel and Patrick Theato
Macromolecules 2010 Volume 43(Issue 10) pp:4638-4645
Publication Date(Web):April 27, 2010
DOI:10.1021/ma1005759
The influence of the chemical structure of both end groups onto the lower critical solution temperature (LCST) of poly[oligo(ethylene glycol) monomethyl ether methacrylate] (POEGMA) in water was systematically investigated. POEGMA of Mn = 3550 g/mol and Mw/Mn = 1.14 prepared by reversible addition−fragmentation chain transfer (RAFT) polymerization was equipped with two different functional end groups in a one-step postpolymerization reaction combining activated esters, functional amines, and functional methane thiosulfonates. As end groups, n-propyl, n-hexadecyl, di(n-octadecyl), poly(ethylene glycol)-550 (PEG), 1H,1H-perfluorononyl, azobenzene, and trimethylethylammonium groups were systematically combined with methyl, n-hexadecyl, and 1H,1H,2H,2H-perfluorooctyl groups. Polymers were characterized by gel permeation chromatography, dynamic light scattering, and turbidimetry. Hydrophobic end groups at either end of the polymer chain decreased the LCST. For hydrophobic groups at both ends of the chain their influence was additive. Two large hydrophobic end groups allowed micelle formation below the LCST and an LCST higher than to be expected from nonaggregated polymers. The strongest hydrophobic effect was found for rigid aromatic end groups, which was attributed to their incompatibility with the flexible polymer chain. Charged end groups increased the LCST and could compensate for the effect of hydrophobic end groups at the opposite end group. PEG end groups could mask a hydrophobic influence of the opposite end group and stabilized the LCST.
Co-reporter:Krishna C. Etika, Florian D. Jochum, Michael A. Cox, Philipp Schattling, Patrick Theato, and Jaime C. Grunlan
Macromolecules 2010 Volume 43(Issue 22) pp:9447-9453
Publication Date(Web):October 25, 2010
DOI:10.1021/ma101696q
Despite their immense potential, the ability to control the dispersion and microstructure of carbon nanotubes remains a hurdle for their widespread use. Stimuli-responsive polymers show conformational changes with an applied external stimulus (pH, temperature, light, etc.). The dispersion of carbon nanotubes by thermoresponsive polymers is shown to enable the macroscopic properties of aqueous suspensions to be tailored as a function of temperature. This work presents the synthesis, characterization, and use of temperature-responsive poly(N-cyclopropylacrylamide) (PNCPA) polymers containing 1, 3, and 5 mol % pyrene-bearing repeat units to tailor the dispersion state of single-walled carbon nanotubes (SWNT) in water. Turbidity measurements show that the lower critical solution temperature (LCST) of PNCPA decreases with increasing pyrene content. Viscosity measurements on aqueous SWNT suspensions stabilized with pyrene-functionalized PNCPA show highly entangled and well-dispersed nanotube microstructure above and below the LCST of the polymer, respectively. UV−vis spectra also confirm that nanotube stabilization by these polymers is dependent upon the pyrene content. Drying of these suspensions produces composites whose microstructure and electrical conductivity vary with drying temperature and pyrene content of the stabilizing polymer. This temperature-dependent dispersion behavior has significant implications for the processing of carbon nanotubes and tailoring of composite properties. Such stimuli-controlled dispersion of carbon nanotubes could have a variety of applications in nanoelectronics, sensing, and drug and gene delivery systems.
Co-reporter:Peter J. Roth, Florian D. Jochum, Rudolf Zentel and Patrick Theato
Biomacromolecules 2010 Volume 11(Issue 1) pp:
Publication Date(Web):November 30, 2009
DOI:10.1021/bm901095j
Reversible addition−fragmentation chain transfer (RAFT) polymerization was used to synthesize poly[diethylene glycol monomethylether methacrylate] (PDEGMA) (Mn = 6250 g/mol, PDI = 1.14) with a pentafluorophenyl (PFP) activated ester and a dithioester end group. The hormone thyroxin (T4) was quantitatively attached to the PFP activated ester α end group via its amino group. The ω-terminal dithioester was not harmed by this reaction and was subsequently aminolyzed in the presence of N-biotinylaminoethyl methanethiosulfonate, yielding a polymer with a thyroxin and a biotin end group with very high heterotelechelic functionality. The polymer was characterized by 1H, 13C, and 19F NMR, UV−vis, and IR spectroscopy and gel permeation chromatography. The thyroxin transport protein prealbumin with two thyroxin binding sites and streptavidin, which has four biotin binding sites, was conjugated using the biotarget labeled polymer, resulting in the formation of a protein−polymer network, confirming the heterotelechelic nature of the polymer. Polymer−protein microgel formation was observed with dynamic light scattering. To realize a directed protein assembly, prealbumin was immobilized onto a surface, exposing one of its two thyroxin binding groups and thus allowing the conjugation with the thyroxin α end group of the heterotelechelic polymer. The biotin ω end group of the attached polymer layer enabled the subsequent immobilization of streptavidin, yielding a defined multilayer system of two proteins connected with the synthetic polymer (efficiency of streptavidin immobilization 81% based on prealbumin). Without the polymer, no streptavidin immobilization occurred. The layer depositions were monitored by surface plasmon resonance. The synthetic approach of combining PFP activated esters with functional MTS reagents presents a powerful method for obtaining well-defined heterotelechelic (bio-) functionalized polymers.
Co-reporter:Florian D. Jochum, Peter J. Roth, Daniel Kessler, and Patrick Theato
Biomacromolecules 2010 Volume 11(Issue 9) pp:
Publication Date(Web):August 20, 2010
DOI:10.1021/bm1006085
A poly(oligo(ethylene glycol) monomethyl ether methacrylate)-block-poly(N-isopropyl methacrylamide) (POEGMA-b-PNIPMAM) block copolymer with a biotin end group on the PNIPMAM block as a biotarget was synthesized as a model system for temperature-controlled polymer immobilization. The synthesis was based on RAFT polymerization followed by postpolymerization modification of an activated ester precursor block and an exchange of the dithioester end group within one step. NMR, differential scanning calorimetry (DSC), dynamic light scattering (DLS), and turbidimetry measurements were performed to investigate the stimulus-responsive properties. The double thermoresponsive POEGMA-b-PNIPMAM with biotin end group showed a temperature-dependent multistage assembly behavior as it was completely soluble in water at temperatures below the LCST of both blocks, formed micellar structures above the LCST of PNIPMAM but below the LCST of POEGMA, or precipitated from solution above the LCST of both blocks. At room temperature, the polymer could be immobilized onto a streptavidin surface via its biotin end group, as shown in surface plasmon resonance (SPR) experiments. At 50 °C, at which the block copolymer formed micelles trapping the biotin target within the PNIPMAM core, no immobilization was observed, showing that the biological binding ability of the model could be controlled via external stimuli.
Co-reporter:Kerstin T. Wiss
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 21) pp:4758-4767
Publication Date(Web):
DOI:10.1002/pola.24267
Abstract
The synthesis of block copolymers via polymer conjugation of well-defined building blocks offers excellent control over the structures obtained, but often several coupling strategies need to be explored to find an efficient one depending on the building blocks. To facilitate the synthesis of polymers with adjustable functional end-groups for polymer conjugation, we report on the combination of activated ester chemistry with RAFT polymerization using a chain transfer agent (CTA) with a pentafluorophenyl ester (PFP-CTA), which allows for flexible functionalization of either the CTA prior to polymerization or the obtained polymer after polymerization. Different polymethacrylates, namely PMMA, P(t-BuMA) and PDEGMEMA, were synthesized with an alkyne-CTA obtained from the aminolysis of the PFP-CTA with propargylamine, and the successful incorporation of the alkyne moiety could be shown via 1H and 13C NMR spectroscopy and MALDI TOF MS. Further, the reactive α-end-groups of polymers synthesized using the unmodified PFP-CTA could be converted into azide and alkyne end-groups after polymerization, and the high functionalization efficiencies could be demonstrated via successful coupling of the resulting polymers via CuAAC. Thus, the PFP-CTA allows for high combinatory flexibility in polymer synthesis facilitating polymer conjugation as useful method for the synthesis of block copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010
Co-reporter:Daniel Klinger;Katja Nilles
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 4) pp:832-844
Publication Date(Web):
DOI:10.1002/pola.23832
Abstract
Two synthetic routes to polymeric 1-imino pyridinium ylides as new photoreactive polymeric architectures were investigated. In the first approach, polymerization of newly synthesized 1-imino pyridinium ylide containing monomers yielding their polymeric analogues was achieved by free radical polymerization. Alternatively, reactive precursor polymers were synthesized and converted into the respective 1-imino pyridinium ylide polymers by polymer analogous reactions on reactive precursor polymers. Quantitative conversion of the reactive groups was achieved with pentafluorophenyl ester containing polymers and newly synthesized photoreactive amines as well as by the reaction of poly(4-vinylbenzoyl azide) with a photoreactive alcohol. The polymers obtained by both routes were examined regarding their photoreaction products and kinetics in solution as well as in thin polymer films. Contact angle measurements of water on the polymer films before and after irradiation showed dramatic changes in the hydrophilicity of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 832–844, 2010
Co-reporter:Katja Nilles
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 16) pp:3683-3692
Publication Date(Web):
DOI:10.1002/pola.24152
Abstract
Statistic and block copolymers exhibiting activated ester side groups were synthesized by reversible addition-fragmentation chain transfer polymerization in the presence of cumyl dithiobenzoate, benzyl dithiobenzoate, and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid as chain transfer agents. Pentafluorophenyl methacrylate and pentafluorophenyl 4-vinylbenzoate were used to enable a sequential functionalization of the obtained copolymers by conversion of the activated esters with different amines. 1H NMR spectroscopy, 19F NMR spectroscopy, and FTIR spectroscopy showed the successful step-by-step conversion of the different activated esters by aniline followed by aliphatic amines, thereby realizing a sequential functionalization of block copolymers with just one specific reactive group. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3683–3692, 2010
Co-reporter:Jinhwa Seo, Philipp Schattling, Thomas Lang, Florian Jochum, Katja Nilles, Patrick Theato and Kookheon Char
Langmuir 2010 Volume 26(Issue 3) pp:1830-1836
Publication Date(Web):September 18, 2009
DOI:10.1021/la902574z
We demonstrate that chemically stable, multifunctional polymer thin films can be obtained using the layer-by-layer (LbL) deposition based on covalent bonds between adsorbing chains. Poly(pentafluorophenyl-4-vinylbenzoate) (P1) or poly(pentafluorophenylacrylate) (P2) polymers were assembled with poly(allyl amine) (PAAm) to yield LbL multilayer films through amide bond formation by the reaction between activated esters of P1 or P2 and amine groups in PAAm, which was quantitatively monitored by Fourier transform infrared spectroscopy (FT-IR). It was found that the difference in the solubility of P1 and P2 against ethanol, which was used as the solvent for PAAm, during the LbL deposition yields different reaction conversion for the activated esters in either P1 or P2: the reaction conversion of P2 is higher than the conversion with P1. In addition, free (or unreacted) activated esters and amine groups remaining in the PAAm/P1 LbL film were further utilized for the incorporation of multiple functional materials (5-((2-aminoethyl)amino)naphthalene-1-sulfonic acid (EDANS) and Rhodamine B dyes in the present case) by post-treatments in order to further tailor the film properties. It was also demonstrated that the surface functional groups (activated esters) in the LbL films can also be utilized for surface patterning with one functional material, followed by functionalization with a second functional material during the post-treatment throughout the whole film. Finally, the PAAm/P1 and PAAm/P2 LbL films were shown to be quite stable in the extreme pH range, and free-standing films can easily be obtained by the treatment of the films with mild acidic conditions. The versatility of incorporating multiple functional materials into a single multilayer film as well as the excellent physicochemical stability of the covalently bonded multilayer free-standing films proves to be quite useful to design flexible and multifunctional thin film structures for many chemical and biological applications.
Co-reporter:Daniel Kessler, Katja Nilles and Patrick Theato
Journal of Materials Chemistry A 2009 vol. 19(Issue 43) pp:8184-8189
Publication Date(Web):23 Sep 2009
DOI:10.1039/B913753J
Poly(methylsilsesquioxane)-based hybrid polymers carrying orthogonally reactive moieties demonstrate an effective modular approach to creating multi-reactive surface coatings. By a sequential surface-analogous reaction different functions could be immobilized in a defined ratio, resulting in dual- or triple-functionalized surfaces.
Co-reporter:Peter J. Roth;Ki-Se Kim;Su Hak Bae;Byeong-Hyeok Sohn;Rudolf Zentel
Macromolecular Rapid Communications 2009 Volume 30( Issue 14) pp:1274-1278
Publication Date(Web):
DOI:10.1002/marc.200900254
Co-reporter:Daniel Kessler;Maria C. Lechmann;Seunguk Noh;Rüdiger Berger;Changhee Lee;Jochen S. Gutmann
Macromolecular Rapid Communications 2009 Volume 30( Issue 14) pp:1238-1242
Publication Date(Web):
DOI:10.1002/marc.200900196
Co-reporter:Niko Haberkorn;Maria C. Lechmann;Byeong Hyeok Sohn;Kookheon Char;Jochen S. Gutmann
Macromolecular Rapid Communications 2009 Volume 30( Issue 14) pp:1146-1166
Publication Date(Web):
DOI:10.1002/marc.200900213
Co-reporter:Daniel Kessler;Holger Löwe
Macromolecular Chemistry and Physics 2009 Volume 210( Issue 10) pp:807-813
Publication Date(Web):
DOI:10.1002/macp.200800611
Co-reporter:Daniel Kessler;Holger Löwe
Macromolecular Chemistry and Physics 2009 Volume 210( Issue 10) pp:
Publication Date(Web):
DOI:10.1002/macp.200990014
Co-reporter:Kerstin T. Wiss;Daniel Kessler;Timothy J. Wendorff
Macromolecular Chemistry and Physics 2009 Volume 210( Issue 15) pp:1201-1209
Publication Date(Web):
DOI:10.1002/macp.200900156
Co-reporter:Niko Haberkorn, Jochen S. Gutmann and Patrick Theato
ACS Nano 2009 Volume 3(Issue 6) pp:1415
Publication Date(Web):May 19, 2009
DOI:10.1021/nn900207a
Free-standing nanorod arrays of a thermally cross-linked semiconducting triphenylamine were fabricated on conductive ITO/glass substrates via an anodic aluminum oxide (AAO) template-assisted approach. By using a solution wetting method combined with a subsequent thermal imprinting step to fill the nanoporous structure of the template with a cross-linkable triphenylamine derivative, a polymeric replication of the AAO was obtained after thermal curing and selective removal of the template. To obtain well-aligned and free-standing nanorod arrays, aggregation and collapse of the nanorods were prevented by optimizing their aspect ratio and applying a freeze-drying technique to remove the aqueous medium after the etching step. Because of their electrochemical properties and their resistance against organic solvents after curing, these high density nanorod arrays have potential application in organic photovoltaics.Keywords: anodic aluminum oxide; nanorod(s); organic photovoltaics; semiconductive polymer(s); template-assisted patterning; triarylamine
Co-reporter:Daniel Kessler and Patrick Theato
Langmuir 2009 Volume 25(Issue 24) pp:14200-14206
Publication Date(Web):April 16, 2009
DOI:10.1021/la9005949
We have investigated a generally applicable protocol for a substrate-independent reactive polymer coating that offers interesting possibilities for further molecular tailoring via simple wet chemical derivatization reactions. Poly(methylsilsesquioxane)-poly(pentafluorophenyl acrylate) hybrid polymers have been synthesized by RAFT polymerization, and stable reactive surface coatings have been prepared by spin-coating on the following substrates: Si, glass, gold, PMMA, PDMS, and steel. These coatings have been used for a defined adjustment of surface wettability by surface-analogous reaction with various amines (e.g., glutamic acid to obtain hydrophilic surfaces (Θa = 18°) or perfluorinated amines to obtain hydrophobic surfaces (Θa = 138°)). Besides the successful covalent attachment of small molecules and polymers, amino-functionalized nanoparticles could also be deposited on the surface, resulting in nanostructured coatings, thereby expanding the accessible contact angle of hydrophobic surfaces further to Θa = 152°. The surface-analogous conversion of the reactive coating with isopropyl amine produced in situ temperature-responsive coatings. Using the presented simple, generally applicable protocol for substrate-independent reactive polymer coatings, the contact angle of water could be switched reversibly by almost 60°.
Co-reporter:Katja Nilles
Journal of Polymer Science Part A: Polymer Chemistry 2009 Volume 47( Issue 6) pp:1696-1705
Publication Date(Web):
DOI:10.1002/pola.23270
Abstract
The reversible addition fragmentation chain transfer (RAFT) polymerization of five active ester monomers based on 4-vinylbenzoic acid had been investigated. Pentafluorophenyl 4-vinylbenzoate could be polymerized under RAFT conditions yielding polymers with very good control over molecular weight and narrow molecular weight distributions. Following the synthesis of diblock copolymers consisting of polystyrene, polypentafluorostyrene, poly(4-octylstyrene), or poly(4-acetoxystyrene) as an inert block and poly(pentafluorophenyl 4-vinylbenzoate) as a reactive block was successfully performed. The diblock copolymer poly(pentafluoro styrene)-block-poly(pentafluorophenyl 4-vinylbenzoate) had been analyzed by 19F NMR spectroscopy in solution, demonstrating the synthetic potential of pentafluorophenyl 4-vinylbenzoate as an extremely valuable monomer for the synthesis of highly functionalized polymeric architectures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1696–1705, 2009
Co-reporter:Kerstin T. Wiss, Ohm D. Krishna, Peter J. Roth, Kristi L. Kiick and Patrick Theato
Macromolecules 2009 Volume 42(Issue 12) pp:3860-3863
Publication Date(Web):May 13, 2009
DOI:10.1021/ma900417n
Co-reporter:Florian D. Jochum, Patrick Theato
Polymer 2009 50(14) pp: 3079-3085
Publication Date(Web):
DOI:10.1016/j.polymer.2009.05.041
Co-reporter:Daniel Kessler, Peter J. Roth and Patrick Theato
Langmuir 2009 Volume 25(Issue 17) pp:10068-10076
Publication Date(Web):July 2, 2009
DOI:10.1021/la901878h
The key designing in reliable biosensors is the preparation of thin films in which biomolecular functions may be immobilized and addressed in a controlled and reproducible manner. This requires the controlled preparation of specific binding sites on planar surfaces. Poly(methylsilsesquioxane)-poly(pentafluorophenyl acrylates) (PMSSQ-PFPA) are promising materials to produce stable and adherent thin reactive coatings on various substrates. Those reactive surface coatings could be applied onto various materials, for example, gold, polycarbonate (PC), poly(tetrafluoroethylene) (PTFE), and glass. By dipping those substrates in a solution of a desired amine, specific binding sites for protein adsorption could be immobilized on the surface. The versatile strategy allowed the attachment of various linkers, for example, biotin, l-thyroxine, and folic acid. The adsorption processes of streptavidin, pre-albumin, and folate-binding protein were monitored using surface plasmon resonance (SPR), Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy, and atomic force microscopy (AFM). The presented protein immobilization strategy, consisting of four steps (a) spin-coating of PMSSQ-PFPA hybrid polymer from tetrahydrofuran (THF) solution, (b) annealing at 130 °C for 2 h to induce thermal cross-linking of the PMSSQ part, (c) surface analogues reaction with different amino-functionalized specific binding sites for proteins, and (d) controlled assembly of proteins on the surface, may find various applications in future biosensor design.
Co-reporter:Peter J. Roth;Daniel Kessler;Rudolf Zentel
Journal of Polymer Science Part A: Polymer Chemistry 2009 Volume 47( Issue 12) pp:3118-3130
Publication Date(Web):
DOI:10.1002/pola.23392
Abstract
Five different polymers, poly[methyl methacrylate] (PMMA), poly[lauryl methacrylate] (PLMA), poly[diethylene glycol methacrylate] (PDEGMA), poly[N-isopropylacrylamide] (PNIPA), and poly[styrene] (PS) prepared by the RAFT process and thus terminated with dithioesters were aminolyzed in the presence of S-3-butynyl methane thiosulfonate (MTS), which was synthesized in two steps. Analysis of the polymers by 2D NMR, UV–vis absorbance, and gel permeation chromatography revealed them to quantitatively carry acetylene end groups connected with disulfide bridges, indicating that functional MTS reagents can be employed for end group functionalization of RAFT polymers. This versatile method is of advantage compared with conjugations with functional maleimides, where isolation of terminal thiols is often required but inexpedient for poly[(meth)acrylates] because their terminal thiols may undergo backbiting and thus avoid conjugation. The acetylene-terminated polymers were bound to an azide functionalized glass surface in a Cu(I) catalyzed cycloaddition. The modified surfaces exhibited water contact angles corresponding to the polarity of the attached polymers. In the case of the stimulus responsive polymers PNIPA and PDEGMA, the surfaces showed temperature-dependent contact angles. The disulfide bond connecting the polymers to the surface could be selectively cleaved and resulted in all surfaces having the same contact angle, independent of the nature of the polymer prior attached to the surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3118–3130, 2009
Co-reporter:Nadine Metz and Patrick Theato
Macromolecules 2009 Volume 42(Issue 1) pp:37-39
Publication Date(Web):December 15, 2008
DOI:10.1021/ma802279v
Co-reporter:Florian D. Jochum and Patrick Theato
Macromolecules 2009 Volume 42(Issue 16) pp:5941-5945
Publication Date(Web):July 2, 2009
DOI:10.1021/ma900945s
Two different series of polyacrylamides containing different amounts of salicylideneaniline moieties have been synthesized via a double polymer analogous reaction of poly(pentafluorophenyl acrylate) (PPFPA). All copolymers were designed to exhibit a lower critical solution temperature (LCST) in aqueous solution, which was dependent on (i) the amount of incorporated chromophoric salicylideneaniline groups and (ii) the isomerization state of the respective salicylideneaniline group. Higher LCST values were measured for UV-irradiated solutions of the copolymers in comparison to the nonirradiated copolymer solutions. A maximum difference in the LCST of up to 13 °C was found for poly(N-cyclopropylacrylamide) copolymer containing 15.0 mol % of salicylideneaniline groups. Within this temperature range, a reversible solubility change of the copolymer could be induced by irradiation with light.
Co-reporter:Florian D. Jochum, Lisa zur Borg, Peter J. Roth and Patrick Theato
Macromolecules 2009 Volume 42(Issue 20) pp:7854-7862
Publication Date(Web):September 2, 2009
DOI:10.1021/ma901295f
Telechelic thermo- and light-responsive polymers based on poly(oligo(ethylene glycol) methyl ether methacrylate) P(OEGMA) with azobenzene functionalities at the end groups were synthesized. In a reversible addition−fragmentation chain transfer (RAFT) polymerization using a functionalized chain transfer agent (CTA) containing a pentafluorophenyl (PFP) activated ester, oligo(ethylene glycol) methyl ether methacrylate (OEGMA, Mn ∼ 300 g mol−1) could successfully be polymerized with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from this CTA possessed an activated ester at the α-end of the polymer chain as well as a dithioester ω-terminus. The ω-dithioester group of each polymer chain could quantitatively be either removed with AIBN treatment or substituted with a PFP ester by using a modified diazo compound. As a consequence, a postmodifiaction of the telechelic reactive end groups was possible through a polymer analogous reaction with amino-functionalized azobenzene. P(OEGMA) polymers containing azobenzene end groups showed a reversible light- and temperature-controlled phase transition in water. Higher values for the lower critical solution temperature (LCST) were measured after irradiation of the aqueous polymer solutions due to the higher polarity of cis-azobenzene. The LCST differences between irradiated and nonirradiated solutions increased linearly upon the ratio of azobenzene units up to 4.3 °C.
Co-reporter:Peter J. Roth and Patrick Theato
Chemistry of Materials 2008 Volume 20(Issue 4) pp:1614
Publication Date(Web):January 26, 2008
DOI:10.1021/cm702642e
Functionalized gold nanoparticles have been prepared in an organic solvent by a two-phase reduction method in ethyl acetate and water using bis(6-hydroxyhexyl) disulfide bis(2-bromoisobutyl) ester, bis(6-acetyloxyhexyl) disulfide, and bis(5-carboxypentyl) disulfide bis(pentafluorophenyl) ester as stabilizing ligands. This procedure features the advantages that no phase transfer agent was necessary during the preparation of the gold nanoparticles and that the reducing conditions were mild enough to utilize functional disulfide ligands. The obtained gold nanoparticles with typical sizes between 2 and 5 nm could be precipitated and redispersed without any irreversible aggregation. Using these nanoparticles the stimuli-responsive polymers poly(N-isopropylacrylamide) and poly(N-cyclopropylacrylamide) could be grafted from the surface. Also, the grafting of polymers onto gold nanoparticles could be demonstrated with nanoparticles featuring pentafluorophenyl ester groups. The reactive character of gold nanoparticles featuring a pentafluorophenyl ester groups on the surface could also be applied in the preparation of multilayers on the basis of covalent bonds between the gold nanoparticles and polyallylamine.
Co-reporter:Sewon Oh, Jin-Kyu Lee, Patrick Theato and Kookheon Char
Chemistry of Materials 2008 Volume 20(Issue 22) pp:6974
Publication Date(Web):October 28, 2008
DOI:10.1021/cm801421w
Thermally stable vinyl polymerized polynorbornene (PNB) is one of the challenging materials in porous low dielectric films for packaging applications. Nanoporous PNB thin films were obtained with poly(d,l-lactide) (PLA)-grafted norbornene copolymers. Thermally labile PLA chains act as pore generators in PNB films. Thermally stable PNB main chains were synthesized by Pd-catalyzed vinyl polymerization and PLA side chains were grafted onto the PNB main chains by ring opening polymerization. The brittle and poor processible properties of PNB could easily be controlled by the copolymerization with norbornene derivatives. In thin films, the PLA chains were found to thermally decompose at about 250 °C while the PNB matrix was stable during this pore generating process. The porosity of the porous PNB thin films could be controlled up to 18% with pore sizes below 5 nm range by varying the chain length of grafted PLA. Introduction of cross-linking epoxy groups onto the PNB main chains resulted in the formation of well-defined nanopores without any extensive pore collapse during the vitrification of the PNB matrix. Additionally, it is demonstrated that the photopatterning of the thin films could be achieved using photoinitiator.
Co-reporter:Daniel Kessler;Carmen Teutsch
Macromolecular Chemistry and Physics 2008 Volume 209( Issue 14) pp:1437-1446
Publication Date(Web):
DOI:10.1002/macp.200800146
Co-reporter:Daniel Kessler;Carmen Teutsch
Macromolecular Chemistry and Physics 2008 Volume 209( Issue 14) pp:
Publication Date(Web):
DOI:10.1002/macp.200890025
Co-reporter:Daniel Kessler and Patrick Theato
Macromolecules 2008 Volume 41(Issue 14) pp:5237-5244
Publication Date(Web):June 21, 2008
DOI:10.1021/ma800570x
New stable and adherent coating materials have been synthesized on the basis of inorganic/organic hybrid polymers. As the inorganic part, different poly(silsesquioxanes) (PSSQ) have been functionalized to act as polymeric chain transfer agents (CTAs) for a reversible addition fragmentation chain transfer polymerization, thereby determining the starting point of a controlled radical polymerization of vinyl-type monomers. Using two different CTAs acrylates, we have successfully polymerized methacrylates and styrene under RAFT polymerization conditions. Different monomers were copolymerized in such an organic block to incorporate multiple functionalities. The variation of the block ratios and the secondary condensation behavior of the inorganic block were investigated. Finally, these materials were used as surface coating materials on silicon, glass, metal, and polymeric substrates. Successful surface functionalization was demonstrated by contact angle measurements. The stability of the film and the adhesion on the substrate were tested in an ISO tape test.
Co-reporter:Peter J. Roth, Kerstin T. Wiss, Rudolf Zentel and Patrick Theato
Macromolecules 2008 Volume 41(Issue 22) pp:8513-8519
Publication Date(Web):October 23, 2008
DOI:10.1021/ma801681b
A diazo initiator and a chain transfer agent (CTA), both containing a pentafluorophenyl (PFP) activated ester, were synthesized. In a RAFT polymerization using the functionalized chain transfer agent (PFP-CTA), methyl methacrylate (MMA), diethylene glycol monomethyl ether methacrylate (DEGMA), poly(ethylene glycol) monomethyl ether methacrylate (PEGMA), and lauryl methacrylate (LMA) could successfully be polymerized into homopolymers and diblock copolymers with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from the PFP−CTA possessed an activated ester at the α-end of the polymer chain, which could be reacted with amines with high conversions. The terminal ω-dithioester group of each polymer chain could quantitatively be removed by treating the polymer with an excess of AIBN, leaving the α-PFP ester functionality intact. Accordingly, the pentafluorophenyl ester diazo compound could successfully be employed to functionalize RAFT polymers with a PFP ester at their ω-end. As a consequence, functionalization of both end groups was possible and led to telechelic polymers, exhibiting an active ester at both ends of the polymer chain. As an example, a high molecular weight PMMA was prepared by polycondensation with ethylenediamine.
Co-reporter:Patrick Theato
Journal of Polymer Science Part A: Polymer Chemistry 2008 Volume 46( Issue 20) pp:6677-6687
Publication Date(Web):
DOI:10.1002/pola.22994
Abstract
Monomers bearing an activated ester group can be polymerized under various controlled polymerization techniques, such as ATRP, NMP, RAFT polymerization, or ROMP. Combining the functionalization of polymers via polymeric activated esters with these controlled polymerization techniques generate possibilities to realize highly functionalized polymer architectures. Within this highlight two different research areas of activated esters in polymer science will be discussed: (i) the preparation of defined reactive polymer architectures by controlled polymerization techniques and (ii) the preparation of defined reactive thin films. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6677–6687, 2008
Co-reporter:Hye Jin Park, Junkyung Kim, Ji Young Chang and Patrick Theato
Langmuir 2008 Volume 24(Issue 18) pp:10467-10473
Publication Date(Web):August 21, 2008
DOI:10.1021/la801341t
A mutilayered film was prepared by layer-by-layer (LBL) assembly of active ester modified multiwalled carbon nanotubes (MWCNTs) and poly(allylamine hydrochloride) (PAH). For this purpose, carboxylic groups on the surface of the oxidized MWCNTs were converted to the acyl chlorides by their reaction with thionyl chloride. Subsequent reaction of the acyl chlorides with pentafluorophenol formed the active esters. These active ester modified MWCNTs (MWCNTs-COOC6F5) were air-stable and moisture resistant, but showed a high reactivity toward primary or secondary amines resulting in amide bonds. For the preparation of a multilayered film, the surface of a quartz slide was first activated and sacrificial double layers of PAH and poly(sodium 4-styrene sulfonate) (PSS) were deposited. Subsequently, LBL assembly of MWCNTs-COOC6F5 and PAH was then conducted on these double layers [(PAH/PSS)2]. In the process of the assembly, a reaction occurred between the active ester on the surface of MWCNTs and the amine groups of polyallylamine yielding amide bonds, which resulted in a mechanically stable thin film. A free-standing film was obtained after dissolving the sacrificial layer [(PAH/PSS)2] in a concentrated aqueous NaOH solution. The surface resistance of the multilayered film with 20 bilayers decreased to around 10 kΩ while remaining a reasonable transparency (70% at 500 nm).
Co-reporter:M. Barz, M. Tarantola, K. Fischer, M. Schmidt, R. Luxenhofer, A. Janshoff, P. Theato and R. Zentel
Biomacromolecules 2008 Volume 9(Issue 11) pp:
Publication Date(Web):October 15, 2008
DOI:10.1021/bm800684b
This paper describes the synthesis of functional amphiphilic poly(N-(2-hydroxypropyl) methacrylamide)-block-poly(lauryl methacrylate) copolymers by RAFT polymerization via the intermediate step of activated ester block copolymers (pentafluoro-phenyl methacrylate). Block copolymers with molecular weights from 12000−28000 g/mol and PDIs of about 1.2 have been obtained. The amphiphilic diblock copolymers form stable super structures (nanoaggregates) by self-organization in aqueous solution. The diameters of these particles are between 100 and 200 nm and depend directly on the molecular weight of the block copolymer. Furthermore, we investigated the impact of these nanoaggregates on cell viability and on the motility of adherent cells. Cytotoxicity was investigated by the MTS test and the fluctuation in cell shape was monitored employing ECIS (electrical cell-substrate impedance sensing). In these investigations, the formed particles are not cell toxic up to a concentration of 2 mg/mL. Thus, our polymeric particles offer potential as polymer therapeutics.
Co-reporter:Peter J. Roth, Daniel Kessler, Rudolf Zentel and Patrick Theato
Macromolecules 2008 Volume 41(Issue 22) pp:8316-8319
Publication Date(Web):October 31, 2008
DOI:10.1021/ma801869z
Co-reporter:Daniel Klinger;Ji Young Chang
Macromolecular Rapid Communications 2007 Volume 28(Issue 6) pp:
Publication Date(Web):21 MAR 2007
DOI:10.1002/marc.200790013
Back Cover: The cover picture shows schematically the successful Curtius rearrangement of poly(4-vinylbenzoyl azide) (P4VBA), which could be thermally transformed into the corresponding isocyanate containing polymer. Reactions on the resulting polymer with various alcohols proceeded quantitatively, making P4VBA a powerful tool as a thermally activated reactive precursor polymer. Further details can be found in the article by D. Klinger, J. Y. Chang, and P. Theato* on page 718.
Co-reporter:Daniel Klinger;Ji Young Chang
Macromolecular Rapid Communications 2007 Volume 28(Issue 6) pp:718-724
Publication Date(Web):21 MAR 2007
DOI:10.1002/marc.200600868
4-Vinylbenzoyl azide was synthesized from p-vinylbenzoic acid and polymerized by free radical polymerization. The obtained polymer contained acyl azide groups which were thermally transformed to the corresponding isocyanato groups. Reactions on these polymers with ethanol, hydroxyethyl methacrylate and 1-pyrenebutanol proceeded quantitatively. Time-resolved FT-IR studies of the reactions with ethanol were carried out by varying the concentration and temperature. The effect of the solvent polarity on the Curtius rearrangement was investigated.
Co-reporter:Patrick Théato;Daniel Kessler
Macromolecular Symposia 2007 Volume 249-250(Issue 1) pp:424-430
Publication Date(Web):28 MAR 2007
DOI:10.1002/masy.200750414
The present paper presents a new method to build up temperature-responsive surfaces. First a poly(silsesquioxane)-block-poly(N-isopropyl-acrylamide) (PMSSQ-b-PNIPAM) was successfully synthesized using RAFT polymerization. Spin-coating or dip-coating of PMSSQ-b-PNIPAM onto glass surfaces resulted in temperature-responsive surfaces. Surface ATR FT-IR measurements proofed the successful surface modification using PMSSQ-b-PNIPAM. IR fine structures of PNIPAM and PMSSQ could be assigned, respectively. In capillary rise experiments a change of the meniscus height measured at temperatures below or above LCST was observed, indicating a different wetting behavior. Thus, a simple spin- or dip-coating step results in a clean and temperature-responsive surface.
Co-reporter:Nicolas Vogel;Patrick Théato
Macromolecular Symposia 2007 Volume 249-250(Issue 1) pp:383-391
Publication Date(Web):28 MAR 2007
DOI:10.1002/masy.200750408
Exo-5-norbornene-2-carboxylic acid pentafluorophenyl ester was synthesized from 5-norbornene-2-carboxylic acid and polymerized by ring-opening metathesis polymerization. The obtained polymers were soluble polymeric active esters that could be used for the preparation of multifunctional polymers. The molecular weight of the polymers was controlled by variation of the monomer to initiator ratio. The precursor polymers reacted quantitatively with primary and secondary amines. Time resolved FT-IR studies at different temperatures of the polymer analogous reactions were performed and rate constants were determined.
Co-reporter:Patrick Theato Dr.
Angewandte Chemie 2007 Volume 119(Issue 23) pp:
Publication Date(Web):24 MAY 2007
DOI:10.1002/ange.200700041
Die gängigsten Begriffe auf dem Gebiet der Polymere mit ionisierbaren oder ionischen Gruppen und der Polymere, die Ionen enthalten, werden hier definiert, wobei ausschließlich organische Polymere berücksichtigt wurden.
Co-reporter:Ulrich Jonas Dr. Dr.
Angewandte Chemie 2007 Volume 119(Issue 11) pp:
Publication Date(Web):26 FEB 2007
DOI:10.1002/ange.200603214
Hier werden die Ausdrücke definiert, die im Bereich von Polymerreaktionen und funktionellen Polymeren am geläufigsten sind. Dabei wurden nur Begriffe aufgenommen, die für Polymersysteme spezifisch sind. Die Zusammenstellung ist in drei Abschnitte unterteilt: Im ersten werden die Begriffe definiert, die sich auf Polymerreaktionen beziehen. Die Namen spezifischer chemischer Reaktionen wurden nicht aufgenommen, auch nicht in Fällen, in denen die Reaktionen wichtig für das Gebiet der Polymerreaktionen sind. Im zweiten Abschnitt werden Begriffe zu polymeren Reaktanten und reaktiven polymeren Materialien definiert, und im dritten Begriffe, die funktionelle polymere Materialien beschreiben.
Co-reporter:Nadine Metz;Daniel Kessler
Macromolecular Symposia 2007 Volume 254(Issue 1) pp:34-41
Publication Date(Web):10 AUG 2007
DOI:10.1002/masy.200750805
Summary: To create stable, adherent and reactive surface coatings, a hybrid polymer composed of poly(methylsilsesquioxane) (PMSSQ) and poly(pentafluorophenyl acrylate) PFPA with a Mn of 32000 g/mol was prepared by a RAFT polymerization procedure. These hybrid polymer has been used for coating experiments. The PFPA part enabled a variable functionalization of the coating afterwards. The stability on various substrates (e.g. glass, PMMA, steel) was tested in an ISO tape test. These reactive surface coatings were modified using different amines, such as amino-terminated PEG, dodecyl amine and N-isopropyl amine. The conversion was analyzed by FT-IR and contact angle measurements.
Co-reporter:Marc Eberhardt;Patrick Théato;Marc Eberhardt;Patrick Théato
Macromolecular Rapid Communications 2005 Volume 26(Issue 18) pp:1488-1493
Publication Date(Web):8 SEP 2005
DOI:10.1002/marc.200500390
Summary: Reversible addition fragmentation chain transfer (RAFT) polymerization of pentafluorophenyl methacrylate (PFMA) was carried out in the presence of cumyldithiobenzoate and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid, respectively. These chain transfer agents with 2,2′-azoisobutyronitrile (AIBN) as initiator yielded the active ester polymer poly(PFMA) with up to 17 000 g · mol−1 and low polydispersity index ( < 1.2). Kinetic analysis using 19F NMR spectroscopy and gel permeation chromatography (GPC) measurements showed controlled polymerization behavior for both chain transfer agents. Successful preparation of linear diblock copolymers consisting of an active ester block and methyl methacrylate, N-acryloylmorpholine, or N,N-diethylacrylamide, respectively, could be demonstrated. These polymers could easily react with amines in a polymer analogous reaction to form multifunctional polymers.
Co-reporter:Patrick Theato, Kook J. Kim and Do Y. Yoon
Physical Chemistry Chemical Physics 2004 vol. 6(Issue 7) pp:1458-1462
Publication Date(Web):02 Mar 2004
DOI:10.1039/B314601B
Novel organic–inorganic hybrid block copolymers based on poly(methylsilsesquioxanes)
(PMSSQs) have been synthesized. Two routes to functionalized PMSSQs are presented and from both atom transfer radical polymerization of methylmethacrylate could be performed. Copolymers with different block ratios have been polymerized and were characterized. In particular, thermal properties were investigated by TGA and the promising thermal decomposition behaviour makes the copolymers potential candidates as pore generators in future nanoporous materials. Additionally, these copolymers were analysed as surface coatings of regular PMMA. Contact angle measurements proved the dramatic effect on the surface properties of such modified PMMA.
Co-reporter:Florian D. Jochum and Patrick Theato
Chemical Communications 2010 - vol. 46(Issue 36) pp:NaN6719-6719
Publication Date(Web):2010/08/17
DOI:10.1039/C0CC01288B
In this communication, the synthesis and characterization of thermo- and light responsive block copolymers is reported. PEO-b-PNIPAM polymers with azobenzene moieties were prepared and analyzed by turbidimetry, fluorescence, NMR and DLS measurements. A temperature controlled reversible formation as well as a light induced disruption and reformation of micellar structures in water was found.
Co-reporter:Daniel Kessler, Katja Nilles and Patrick Theato
Journal of Materials Chemistry A 2009 - vol. 19(Issue 43) pp:NaN8189-8189
Publication Date(Web):2009/09/23
DOI:10.1039/B913753J
Poly(methylsilsesquioxane)-based hybrid polymers carrying orthogonally reactive moieties demonstrate an effective modular approach to creating multi-reactive surface coatings. By a sequential surface-analogous reaction different functions could be immobilized in a defined ratio, resulting in dual- or triple-functionalized surfaces.
![4-Nitro-7-(piperazin-1-yl)benzo[c][1,2,5]oxadiazole](/data/chemimg/461700/139332-66-4.png)
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