Compared with traditional porous carbon materials, two-dimensional (2D) porous carbon materials with a high aspect ratio and a continuous hierarchical porous structure are promising candidates for the construction of supercapacitor electrode materials. Herein, well-defined, graphene-based conjugated microporous polymer sheets (G-CMPs) were prepared in a graphene-inspired synthetic strategy. Thereby, 4-iodophenyl-substituted graphene (RGO-I) templates not only effectively hinder the aggregation between the adjacent graphene layers but also provide an efficient template for the growth of porous CMPs onto the graphene surface. Moreover, our G-CMPs could be converted into 2D porous carbon nanosheets by pyrolysis. The synergism of high aspect ratio and high specific surface area, the presence of graphene-based conduction paths and hierarchical pore systems ensure a high ion-accessible surface area of the corresponding supercapacitor electrodes thus allowing accelerated electron and ion diffusion/transport and leading to high specific capacitance as well as good rate capability and cycling stability.

Spin-coated film of poly(vinylidenefluoride-hexafluoropropylene) (P(VDF-HFP)) acts as a cathode/anode buffer layer in polymer solar cells (PSCs) with conventional/inverted device structures. Such devices show optimized performances comparable with the controlled device, making P(VDF-HFP) a good substitute for LiF/MoO₃ as a cathode/anode buffer layer. Ultraviolet photoelectron spectroscopy (UPS) and Kelvin force microscope (KFM) measurements show that increased surface potential of active layers improves cathode contact. In piezoresponse force microscopy (PFM) measurement, P(VDF-HFP) responds to applied bias in phase curve, showing tunable dipole. This tunable dipole renders surface potential under applied bias. As a result, open-circuit voltage of devices alters instantly with poling voltage. Moreover, positive poling of P(VDF-HFP) together with simultaneous oxidation of Ag gradually improves performance of inverted structure device. Integer charge transfer (ICT) model elucidates improved electrode contacts by dipole tuning, varying surface potential and vacuum level shift. Understanding the function of dipole makes P(VDF-HFP) a promising and versatile buffer layer for PSCs.

Despite nearly two decades of research, the absence of ideal, flexible, and transparent electrodes has been the biggest bottleneck for realizing flexible and printable electronics via roll-to-roll (R2R) method. A fabrication of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate):graphene:ethyl cellulose (PEDOT:PSS:G:EC) hybrid electrodes by R2R process, which allows for the elimination of strong acid treatment. The high-performance flexible printable electrode includes a transmittance (T) of 78% at 550 nm and a sheet resistance of 13 Ω sq⁻¹ with excellent mechanical stability. These features arise from the PSS interacting strongly with the ethyoxyl groups from EC promoting a favorable phase separation between PEDOT and PSS chains, and the highly uniform and conductive G:EC enable rearrangement of the PEDOT chains with more expanded conformation surrounded by G:EC via the π–π interaction between G:EC and PEDOT. The hybrid electrodes are fully functional as universal electrodes for outstanding flexible electronic applications. Organic solar cells based on the hybrid electrode exhibit a high power conversion efficiency of 9.4% with good universality for active layer. Moreover, the organic light-emitting diodes and photodetector devices hold the same level to or outperform those based on indium tin oxide flexible transparent electrodes.

A heterostructured semiconductor–metal ZnOAg nanoparticle (NP) composite was constructed through a straightforward photocatalytic strategy by using UV irradiation of ZnO NPs and an aqueous solution of Ag precursor. The ZnOAg NP composites serve as an effective cathode-modifying layer in polymer solar cells (PSCs) with increased short-circuit current density owing to the light-trapping effect, and improved optical and electrical conductivity properties compared with pure ZnO NPs. The Ag NPs, which are photodeposited in situ on ZnO NPs, can act as effective antennas for incident light to maximize light harvesting and minimize radiative decay or nonradiative losses, consequently resulting in the enhanced photogeneration of excitons in PSCs. Systematic photoelectron and -physical investigations confirm that heterostructured ZnOAg NPs can significantly improve charge separation, transport, and collection, as well as lower charge recombination at the cathode interface, leading to a 14.0 % improvement in air-processed device power conversion efficiency. In addition, this processable, cost-effective, and scalable approach is compatible with roll-to-roll manufacturing of large-scale PSCs.

A synergistic approach combining new material design and interfacial engineering of devices is adopted to produce high efficiency inverted solar cells. Two new polymers, based on an indacenodithieno[3,2-b]thiophene-difluorobenzothiadiazole (PIDTT-DFBT) donor–acceptor (D–A) polymer, are produced by incorporating either an alkyl thiophene (PIDTT-DFBT-T) or alkyl thieno[3,2-b]thiophene (PIDTT-DFBT-TT) π-bridge as spacer. Although the PIDTT-DFBT-TT polymer exhibits decreased absorption at longer wavelengths and increased absorption at higher energy wavelengths, it shows higher power conversion efficiencies in devices. In contrast, the thiophene bridged PIDTT-DFBT-T shows a similar change in its absorption spectrum, but its low molecular weight leads to reduced hole mobilities and performance in photovoltaic cells. Inverted solar cells based on PIDTT-DFBT-TT are explored by modifying the electron-transporting ZnO layer with a fullerene self-assembled monolayer and the MoO₃ hole-transporting layer with graphene oxide. This leads to power conversion efficiencies as high as 7.3% in inverted cells. PIDTT-DFBT-TT's characteristic strong short wavelength absorption and high efficiency suggests it is a good candidate as a wide band gap material for tandem solar cells.

The utilization of a conjugated polyelectrolyte-ionic liquid crystal (CPE-ILC) complex as electron transporting layer (ETL) to improve the compatibility between the ITO and hydrophobic active layer and to promote the dipole orientation at cathode interface is reported. Simultaneously, a hole transporting layer (HTL) of solution processed tungsten oxide together with poly(2,6-bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-alt-4,6-Dibromo-thieno[3,4-b]thiophene-2-carboxylic acid 2-[2-(2-methoxy-ethoxy)-ethoxy]-ethyl ester) (PBDTT-TT-TEG) efficiently shifts the work function of Ag electrode in this device. The interfacial modification of these interlayers achieves energy alignment at both electrodes. The power conversion efficiency (PCE) of the PSC based on ITO/PFN-CbpSO/PBDTTT-C-T:PC₇₀BM/PBDTT-TT-TEG/WO₃/Ag with solution processed interlayers reaches to 7.8%. It is worthy to note that except for the electrodes, all layers of device are fabricated by solution process at room temperature and without annealing. In the case of incorporating ZnO layer into this device, the device efficiency further increases to 8.5%, which is the best value reported from PBDTTT-C-T:PC₇₀BM-based solar cells with solution processed interlayers at both electrodes so far.

A series of novel poly[(butylene succinate)-co-diolisobutyl]-[ polyhedral oligomeric silsesquioxane] (PBS-POSS) copolyesters have been synthesized for the first time directly from diacid and diols via melting polycondensation. Both PBS and POSS segments crystallized as revealed by X-ray diffraction, and the crystallization of PBS was found to be retarded by the incorporation of POSS into PBS chains based on differential scanning calorimetry and rheological results. Moreover, the copolyester containing 3 mol% POSS formed organogels in chloroform by the treatment of shear flow and was more thermally stable than the pristine sample, due to formation of a physically crosslinked network caused by the crystallization of POSS into crystals of larger sizes. © 2013 Society of Chemical Industry

The performance and stability of organic photovoltaic (OPV) devices based upon bulk heterojunction blends of donor and acceptor materials have been shown to be highly dependent on the morphology of the active layer. Block copolymers, which naturally self-assemble into periodic ordered nanostructures, can be utilized in diverse ways to control morphology on a length scale relevant for charge separation, recombination and transportation, which makes them promising candidates for high performance and thermally stable OPV devices. This minireview presents a brief statistical discussion of inter-study correlations and a summary of past interfacial research on block copolymer nanostructuring compatibilizers for OPVs. © 2013 Society of Chemical Industry

The hairy poly(methacrylic acid-co-divinylbenzene)-g-poly(N-isopropylacrylamide) (P(MAA-co-DVB)-g-PNIPAm) nanocapsules with pH-responsive P(MAA-co-DVB) inner shell and temperature-responsive PNIPAm brushes were prepared by combined distillation–precipitation copolymerization and surface thiol-ene click grafting reaction using 3-(trimethoxysilyl)propyl methacrylate-modified silica (SiO₂-MPS) nanospheres as a sacrificial core material. The well-defined PNIPAm was synthesized by a reversible addition fragmentation chain transfer (RAFT) polymerization. The chain end was converted to a thiol by chemical reduction. The PNIPAm was integrated into the nanocapsules via thiol-ene click reaction. The surface thiol-ene click reaction conduced to tunable grafting density of PNIPAm brushes. The grafting densities decreased from 0.70 chains nm⁻² to 0.15 chains nm⁻² with increasing the molecular weight of grafted PNIPAm chains. Using water soluble doxorubicin hydrochloride (DOX·HCl) as a model molecular, the tunable shell permeability of the nanocapsule was investigated in detail. The permeability constant can be tuned by controlling the thickness of the P(MAA-co-DVB) inner shell, the grafting density of PNIPAm brushes, and the environmental pH and temperature. The tunable shell permeability of these nanocapsules results in the release of the loaded guest molecules with manipulable releasing kinetics. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2202–2216

The covalently immobilized multiwalled carbon nanotubes (MWNTs) supported three-dimensional geometry α-diimine nickel, palladium catalysts are prepared by corresponding α-diimine nickel, palladium complexes and activated MWNTs. The molecular structures of the catalysts have been confirmed by X-ray single-crystal analyses, NMR and XPS, as well as elemental analysis. Compared with nickel, palladium catalysts without modification and physical mixing of nickel, palladium catalysts with MWNTs, the MWNTs supported nickel, palladium catalysts show improved activity and productivity in norbornene homopolymerization and copolymerization with polar monomer. The morphology of the resulting polymers obtained from MWNTs-supported nickel(II) complex reveals that the MWNTs are dispersed uniformly in polymer and wrapped by polymers to squeeze out of spherical particles, leading to the enhanced processability and mechanical properties. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3213–3220

Two-dimensional graphene–CdS (G–CdS) semiconductor hybrid nanosheets were synthesized in situ by graphene oxide (GO) quantum wells and a metal–xanthate precursor through a one-step growth process. Incorporation of G–CdS nanosheets into a photoactive film consisting of poly[4,8-bis-(2-ethyl-hexyl-thiophene-5-yl)-benzo[1,2-b:4,5-b]dithiophene-2,6-diyl]-alt-[2-(2-ethyl-hexanoyl)-thieno[3,4-b]thiophen-4,6-diyl] (PBDTTT-C-T) and [6,6]-phenyl C₇₀ butyric acid methyl ester (PC₇₀BM) effectively decreases the exciton lifetime to accelerate exciton dissociation. More importantly, the decreasing energy levels of PBDTTT-C-T, PC₇₀BM, and G–CdS produces versatile heterojunction interfaces of PBDTTT-C-T:PC₇₀BM, PBDTTT-C-T:G–CdS, and PBDTTT-C-T:PC₇₀BM:G–CdS; this offers multi-charge-transfer channels for more efficient charge separation and transfer. The charge transfer in the blend film also depends on the G–CdS nanosheet loadings. In addition, G–CdS nanosheets improve light utilization and charge mobility in the photoactive layer. As a result, by incorporation of G–CdS nanosheets into the active layer, the power-conversion efficiency of inverted solar cells based on PBDTTT-C-T and PC₇₁BM is improved from 6.0 % for a reference device without G–CdS nanosheets to 7.5 % for the device with 1.5wt % G–CdS nanosheets, due to the dramatically enhanced short-circuit current. Combined with the advantageous mechanical properties of the PBDTTT-C-T:PC₇₀BM:G–CdS active layer, the novel CdS-cluster-decorated graphene hybrid nanomaterials provide a promising approach to improve the device performance.

The direct growth of CdS nanocrystals in functional solid-state thermotropic liquid crystal (LC) small molecules and a conjugated LC polymer by in situ thermal decomposition of a single-source cadmium xanthate precursor to fabricate LC/CdS hybrid nanocomposites is described. The influence of thermal annealing temperature of the LC/CdS precursors upon the nanomorphology, photophysics, and optoelectronic properties of the LC/CdS nanocomposites is systematically studied. Steady-state PL and ultrafast emission dynamics studies show that the charge-transfer rates are strongly dependent on the thermal annealing temperature. Notably, annealing at liquid-crystal state temperature promotes a more organized nanomorphology of the LC/CdS nanocomposites with improved photophysics and optoelectronic properties. The results confirm that thermotropic LCs can be ideal candidates as organization templates for the control of organic/inorganic hybrid nanocomposites at the nanoscale level. The results also demonstrate that in situ growth of semiconducting nanocrystals in thermotropic LCs is a versatile route to hybrid organic/inorganic nanocomposites and optoelectronic devices.

A ZnO@reduced graphene oxide–poly(N-vinylpyrrolidone) (ZnO@RGO-PVP) nanocomposite, prepared by in situ growth of ZnO nanoparticles on PVP-decorated RGO (RGO-PVP) was developed as a cathode buffer layer for improving the performance of polymer solar cells (PSCs). PVP not only favors homogeneous distribution of the RGO through the strong π–π interactions between graphene and PVP molecules, but also acts as a stabilizer and bridge to control the in situ growth of sol–gel-derived ZnO nanoparticles on the surface of the graphene. At the same time, RGO provides a conductive connection for independent dispersion of ZnO nanoparticles to form uniform nanoclusters with fewer domain boundaries and surface traps. Moreover, the LUMO level of ZnO is effectively improved by modification with RGO-PVP. Compared to bare ZnO, a ZnO@RGO-PVP cathode buffer layer substantially reduces the recombination of carriers, increases the electrical conductivity, and enhances electron extraction. Consequently, the power conversion efficiency of an inverted device based on thieno[3,4-b]thiophene/benzodithiophene (PTB7):[6,6]-phenyl C₇₁-butyric acid methyl ester (PC₇₁BM) with ZnO@RGO-PVP as cathode buffer layer was greatly improved to 7.5 % with improved long-term stability. The results reveal that ZnO@RGO-PVP is universally applicable as a cathode buffer layer for improving the performance of PSCs.

A new liquid crystalline (LC) acceptor monomer 2,5-bis[4-(4′-cyanobiphenyloxy)dodecyl]-3,6-dithiophen-2-yl-pyrrolo[3,4-c]pyrrole-1,4-dione (TDPPcbp) was synthesized by incorporating cyanobiphenyl mesogens into diketopyrrolopyrrole (DPP). The monomer was copolymerized with bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′] dithiophene (BDT) and N-9′-heptadecanylcarbazole (CB) donors to obtain donor–acceptor alternating copolymers poly[4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene-alt-3,6-bis(thiophen-5-yl)-2,5-bis[4-(4′-cyanobiphenyloxy)dodecyl]-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione] (PBDTDPPcbp) and poly[N-9′-heptadecanyl-2,7-carbazole-alt-3,6-bis(thiophen-5-yl)-2,5-bis[4-(4′-cyano-biphenyloxy)dodecyl]-2,5-dihydropyrrolo[3, 4-c]pyrrole-1,4-dione] (PCBTDPPcpb) with reduced band gap, respectively. The LC properties of the copolymers, the effects of main chain variation on molecular packing, optical properties, and energy levels were analyzed. Incorporating the mesogen cyanobiphenyl units not only help polymer donors to pack well through mesogen self-organization but also push the fullerene acceptor to form optimized phase separation. The bulk heterojunction photovoltaicdevicesshow enhanced performance of 1.3% for PBDTDPPcbp and 1.2% for PCBTDPPcbp after thermal annealing. The results indicate that mesogen-controlled self-organization is an efficient approach to develop well-defined morphology and to improve the device performance. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

An original strategy to construct a new donor–acceptor (D–A)-integrated structure by directly imposing “pull” unit on the “push” moiety to form fused ring architecture has been developed, and poly{N-alkyl-carbazole[3,4-c:5,6-c]bis[1,2,5]thiadiazole-alt-thiophene} (PCBTT) with D–A-integrated structure, in which two 1,2,5-thiadiazole rings are fixed on carbazole in 3-, 4- and 5-, 6-position symmetrically and thiophene is used as bridge, has been synthesized. The interaction between pull and push units has fine tuned the HOMO/LUMO energy levels, and the resulting copolymer covers the solar flux from 300 to 750 nm. The interaction between pull and push units is worth noting that due to the fused five rings inducing strong intermolecular interaction, an extremely short π–π stacking distance of 0.32 nm has been achieved for PCBTT both in powder and solid states. This is the shortest π–π stacking distance reported for conjugated polymers. Additionally, an obvious intramolecular charge transfer and energy transfer from donor units to acceptor units have been detected in this D–A integration. A moderate-to-high open-circuit voltage of ∼0.7 V in PCBTT:[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) (w/w = 1/2) solar cells is achieved due to the low-lying HOMO energy level of PCBTT. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Novel star-shaped hard–soft triblock copolymers, 4-arm poly(styrene)-block-poly [poly(ethylene glycol) methyl ethyl methacrylate]-block-poly{x-[(4-cyano-4′-biphenyl) oxy] alkyl methacrylate} (4PS-PPEGMA-PMAxLC) (x = 3, 10), with different mesogen spacer length are prepared by atom-transfer radical polymerization. The star copolymers comprised three different parts: a hard polystyrene (PS) core to ensure the good mechanical property of the solid-state polymer, and a soft, mobile poly[poly(ethylene glycol) methyl ethyl methacrylate] (PPEGMA) middle sphere responsible for the high ionic conductivity of the solid polyelectrolytes, and a poly{x-[(4-cyano-4′-biphenyl)oxy]alkyl methacrylate} with a birefringent mesogens at the end of each arm to tuning the electrolytes morphology. The star-shaped hard–soft block copolymers fusing hard PS core with soft PPEGMA segment can form a flexible and transparent film with dimensional stability. Thermal annealing from the liquid crystalline states allows the cyanobiphenyl mesogens to induce a good assembly of hard and soft blocks, consequently obtaining uniform nanoscale microphase separation morphology, and the longer spacer is more helpful than the shorter one. There the ionic conductivity has been improved greatly by the orderly continuous channel for efficient ion transportation, especially at the elevated temperature. The copolymer 4PS-PPEGMA-PMA10LC shows ionic conductivity value of 1.3 × 10⁻⁴ S cm⁻¹ (25 °C) after annealed from liquid crystal state, which is higher than that of 4PS-PPEGMA electrolyte without mesogen groups. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4341–4350

A novel D-A alternative conjugated polymer PBDTDMCT containing benzo[1,2-b:4,5-b′]dithiophene (BDT) and dimethyl thiophene-3,4-dicarboxylate (DMCT), was designed and synthesized by Stille cross-coupling reaction. The copolymer exhibited excellent solubility and good thermal stability. The optical band gap determined from the onset of absorption of the polymer film was 2.10 eV. By incorporation of the ester groups into the polymer side chain, the HOMO level of polymer PBDTDMT was tuned to be deep-lying (−5.65 eV). Open-circuit voltage of polymer solar cells constructed based on PBDTDMT and [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) can be tuned to achieve values as high as ca. 1.0 V.

A series of aliphatic biodegradable poly (butylene succinate-co-ethyleneoxide-co-DL-lactide) copolyesters were synthesized by the polycondensation in the presence of dimethyl succinate, 1,4-butanediol, poly(ethylene glycol), and DL-oligo(lactic acid) (OLA). The composition, as well as the sequential structure of the copolyesters, was carefully investigated by ¹H-NMR. The crystallization behaviors, crystal structure, and spherulite morphology of the copolyesters were analyzed by differential scanning calorimetry, wide angle X-ray diffraction, and polarizing optical microscopy, respectively. The results indicate that the sequence length of butylene succinate (BS) decreased as the OLA feed molar ratio increasing. The crystallization behavior of the copolyesters was influenced by the composition and sequence length of BS, which further tuned the mechanical properties of the copolyesters. The copolyesters formed the crystal structures and spherulites similar to those of PBS. The incorporation of more content of ethylene oxide (EO) units into the copolyesters led to the enhanced hydrophilicity. The more content of lactide units in the copolyesters facilitated the degradation in the presence of enzymes. The morphology of the copolyester films after degradation was also studied by the scanning electron microscopy. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

The poly(butoxymethylenenorbornene-co-norbornenemethyl acetate) (PBN/NA) were successfully synthesized via the vinyl addition copolymerization of 2-butoxymethylene norbornene (BN) and norbornene-2-methyl acetate (NA). The poly(butoxymethylenenorbornene-co-norbornenemethanol) (PBN/NOH) was obtained by the de-esterification of PBN/NA. After doping with 4,5-imidazole dicarboxylic acid (IDA) and phosphoric acid (H₃PO₄), the proton exchange membranes with crosslinked structure were obtained and the corresponding morphology, water uptake, proton conductivity, methanol permeability, thermal stability, as well as tensile properties were investigated. The results indicate that the crosslinked membranes showed higher proton conductivity at higher temperatures and lower methanol permeability after incorporation of more content of IDA and H₃PO₄. The PNIH membranes showed lower tensile strength, elongation at break as well as the elastic modulus than pristine PBN/NOH. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

A novel bis(β-ketoamino)Ni(II) complex catalyst, Ni{CF₃C(O)CHC[N(naphthyl)]CH₃}₂, was synthesized, and the structure was solved by a single-crystal X-ray refraction technique. The copolymerization of norbornene with higher 1-alkene was carried out in toluene with catalytic systems based on nickel(II) complexes, Ni{RC(O)CHC[N(naphthyl)]CH₃}₂(RCH₃, CF₃) and B(C₆F₅)₃, and high activity was exhibited by both catalytic systems. The effects of the catalyst structure and comonomer feed content on the polymerization activity and the incorporation rates were investigated. The reactivity ratios were determined to be r_1-octene = 0.009 and r_norbornene = 13.461 by the Kelen–Tüdõs method for the Ni{CH₃C(O)CHC[N(naphthyl)]CH₃}₂/B(C₆F₅)₃ system. The achieved copolymers were confirmed to be vinyl-addition copolymers through the analysis of ¹H-NMR and ¹³C-NMR. The thermogravimetric analysis results showed that the copolymers exhibited good thermal stability (decomposition temperature, T_dec > 400°C), and the glass-transition temperature of the copolymers were observed between 215 and 275°C. The copolymers were confirmed to be noncrystalline by wide-angle X-ray diffraction analysis and showed good solubility in common organic solvents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

A series of aliphatic biodegradable poly(butylene succinate)-co-oligo(L-valine) (PBSVAL) copolyesters were synthesized with dimethyl succinate, 1,4-butanediol (BDO), and oligo(L-valine) (OVL) as reagents. The GPC results show that the weight average molecular weight (M_w) of the copolyester with a feed ratio (PBS/OVL) of 0.9/0.1 (PBSVAL₁₀) is 4.9 × 10⁴ g/mol, and its polydispersity index is 1.68. All the copolyesters were more thermally stable than the pristine poly(butylene succinate) (PBS). The incorporation of valine units into the copolyesters eventually led to the decrease of the crystallization temperature, melting temperature, while increase of crystallization enthalpy and melting enthalpy. The crystal structure of the copolyesters is similar to pure PBS except for higher degrees of crystallinity; also there was a trend to higher degrees of crystallinity with increasing content of valine. From the enzymatic degradation experiment, it is clear that the PBSVAL₁₀ copolyester shows less weight loss as compared to pure PBS which is due to PBSVAL₁₀ with higher degree of crystallinity. The morphology of the copolyester films after degradation was also studied by the scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

A serial of late transition metal complexes, which bearing Benzocyclohexane–ketoarylimine ligand and named as Mt(benzocyclohexane–ketoarylimino)₂ {Mt(bchkai)₂: Mt=Ni or Pd; bchkai=C₁₀H₈(O)CN(Ar)CH₃; Ar=naphthyl or fluoryl}, have been synthesized and characterized. The molecular structures of the ligands and nickel complex have been confirmed by X-ray single-crystal analyses. The nickel complexes exhibited very high activity up to 2.7 × 10⁵ g_polymer/mol_Ni·h and palladium complexes showed high activity up to 2.3 × 10⁵ g_polymer/mol_Pd·h for norbornene (NB) homo-polymerization with tris(pentafluorophenyl)borane as cocatalyst. The four complexes were effective for copolymerization of NB and 5-norbornene-2-carboxylic acid methyl ester (NB-COOCH₃) in relatively high activities (0.1–2.4 × 10⁵ g_polymer/mol_Mt·h) and produced the addition-type copolymers with relatively high molecular weights (0.5 × 10⁵–1.2 × 10⁵ g/mol) as well as narrow molecular weight distributions (PDI < 2 for all polymers). Influences of the metals and comonomer feed content on the polymerization activity as well as on the incorporation rates (20.9–42.6%) were investigated. The achieved NB/NB-COOCH₃ copolymers were confirmed to be noncrystalline, exhibited good thermal stability (T_d > 400°C) and showed good solubility in common organic solvents. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

The biodegradable poly(butylene succinate) (PBS)/poly(ethylene oxide)-polyhedral oligomeric silsesquioxane (PEO-POSS) nanocomposites were prepared by the solution blending and melt-injection methods. The effect of PEO-POSS on the non-isothermal and isothermal crystallization, morphology, as well as mechanical properties of PBS was carefully investigated. The PEO-POSS nanoparticles dispersed well in the PBS matrix, with the diameters around 30 nm. From isothermal crystallization analysis, the incorporation of PEO-POSS enhanced the crystallization of PBS due to the heterogeneous nucleation effect while the crystal structure of PBS remained. PBS/PEO-POSS nanocomposites showed of higher glass transition temperatures than that of neat PBS, attributing to the existence of PEO-POSS decreasing the flexibility of PBS chains. The elongation at break of the PBS/PEO-POSS nanocomposites reached the maximum value with PEO-POSS content of 5 wt%. However, the elastic modulus of PBS decreased after the incorporation of PEO-POSS. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Biodegradable poly(butylene succinate-co-ethylene glycol) (PBSG)/multiwalled carbon nanotube (MWCNT) nanocomposites were successfully prepared through physical blending and silication between PBSG and acyl aminopropyltriethoxysilane functionalized multiwalled carbon nanotube (MWCNT-APTES). Nuclear magnetic resonance (NMR) spectra observations revealed that the PBSG chains were covalently attached to the MWCNT-APTES by hydrolysis. PBSG/MWCNT-APTES nanocomposites after hydrolysis showed excellent interfacial compatibility between PBSG and MWCNT-APTES, which was helpful for the dispersion of MWCNT in the PBSG matrix. The incorporation of MWCNT-APTES accelerated the crystallization of PBSG in the nanocomposites for both approaches of physical blending and hydrolysis due to the heterogeneous nucleation effect of MWCNT while the crystal structure of PBSG was remained. Furthermore, the crystallization rate of PBSG in PBSG/MWCNT-APTES nanocomposites after hydrolysis was slower than that in the nanocomposite by physical blend. The tensile strength and modulus of the nanocomposites increased about 6% and 11% with the addition of only 1 wt% MWCNT-APTES compared with that of neat PBSG, and was larger for the PBSG/MWCNT-APTES nanocomposites after hydrolysis. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

A series of copolyesters were prepared by the direct melt transesterification of poly(trimethylene terephthalate) (PTT) and poly(butylene succinate) (PBS). The sequential structure of the copolyesters was analyzed with proton nuclear magnetic resonance spectroscopy, and the randomness of the copolyesters was calculated to be approximately 0.8. The cocrystallization, thermal behavior, and spherulitic morphology were investigated. The melting points of the copolyesters showed a pseudo-eutectic behavior exhibiting isodimorphic cocrystallization. Wide-angle X-ray diffraction indicated that the copolyesters crystallized in PTT crystals when the butylene succinate (BS) unit content was less than 60% and in the PBS crystals when the BS unit content was greater than 70%. The mechanical properties of the copolyesters were greatly influenced by the sequence lengths of the aromatic and aliphatic units. The incorporation of BS units into the PTT structure led to a faster rate of degradation of the copolyesters because of the decrease in the aromatic sequence length and the increase in the aliphatic sequence length. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The graft copolymer poly(butoxymethylene norbornene-co-norbornenemethylene bromoisobutyrylate) [P(BN/NB)]-graft-poly(hydroxyethyl methacrylate) (PHEMA) was synthesized by the atom transfer radical polymerization of 2-hydroxyethyl methacrylate from a copolymer prepared by two functional norbornene monomers via a vinyl addition mechanism. The graft copolymer P(BN/NB)-g-PHEMA was further crosslinked with 4,5-imidazole dicarboxylic acid (IDA) and then doped with phosphoric acid (H₃PO₄) to form imidazole–H₃PO₄ complexes. The results show that the polynorbornene backbone and crosslinked micromorphology produced low methanol permeability in the membranes (from 1.5 × 10⁻⁷ to 3.8 × 10⁻⁶ cm²/s) and endowed the membranes with good mechanical properties (with elastic modulus values of 692.7 to 159.7 MPa, elongation at break values from 2.7 to 22.7%, and tensile strength at break values from 14.4 to 5.5 MPa) and excellent thermal stability (up to 280°C). Furthermore, the proton conductivities of the membranes increased with increasing temperature and increasing content of IDA/H₃PO₄ in the membranes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A series of biodegradable isosorbide-based copolyesters poly(butylene succinate-co-isosorbide succinate-co-polyethyleneoxide succinate) (PB_xI_yE_zS) were synthesized via bulk polycondensation in the presence of dimethyl succinate (DMS), 1,4-butanediol (BDO), poly(ethylene glycol) (PEG) and isosorbide (ISO). The crystallization behaviors, crystal structure and spherulite morphology of the copolyesters were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM), respectively. The results indicate that the crystallization behavior of the copolyesters was influenced by the content of isosorbide succinate (IS) and polyethyleneoxide succinate (PEOS) units, which further tuned the mechanical and biodegradable properties of the copolyesters. The PB_xI_yE_zS copolyesters, compared to pure poly(butylene succinate), showed lower crystallization temperature, melting temperature, degree of crystallinity and degradation rate while a significant increase in glass transition temperature with increasing isosorbide content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The poly(poly(ethylene glycol) methyl ether methacrylate)- (PPEGMA)-grafted bamboo fiber (BF) (BF@PPEGMA) was successfully synthesized via the esterification and atom transfer radical polymerization (ATRP) methods. The poly(butylenes succinate) (PBS) matrix-based composites including BF and BF@PPEGMA were prepared by a twin-screw extruder. The structure, morphology, as well as the properties of BF@PPEGMA and composites was investigated. The results indicated that PPEGMA was successfully grafted onto the BF surfaces, making BF surfaces rough and less thermally stable. The BF@PPEGMA showed of stronger interactions with PBS matrix than pristine BF, leading to the improvement of tensile modulus, tensile strength, and elongation at break of the composites. The PBS/BF@PPEGMA composites absorbed less water than PBS/BF composites due to the existence of less content of hydroxyl groups after surface modification. Incorporation of BF and BF@PPEGMA facilitated the crystallization of PBS at higher temperatures, leading to formation of regular spherulites without appearance of transcrystallization. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Covalently immobilized silica-supported acetylacetonate dichloride palladium(II) precatalyst is prepared by the reaction of silica particles grafted acetylacetonate ligand further exchange with [Et₄N]₂PdCl₄. The silica-supported catalyst is used in slurry polymerizations of norbornene (NB) to afford a highly productive NB addition polymerization system in combination with B(C₆F₅)₃ cocatalyst. It exhibits productivity of 84 kg of PNB (mol Pd)⁻¹ h⁻¹ at the initial activity, and the catalyst deactivation kinetics in the early stage of polymerization are fitted well by the first-order deactivation kinetics. The obtained vinyl-type polynorbornene is confirmed to be nanosilica hybrid PNB nanocomposite by SEM, TEM with an energy dispersive spectrometer, TGA, and XRD.

Two complexes Mt{C₁₀H₈(O)C[N(C₆H₅)]CH₃}₂ [Mt = Ni(II); Mt = Pd(II)] were synthesized, and the solid-state structures of the complexes have been determined by single-crystal X-ray diffractions. Homopolymerization of norbornene (NB) and copolymerization of NB and 5-norbornene-2-yl acetate (NB-OCOCH₃) were carried out in toluene with both the two complexes mentioned above in combination with B(C₆F₅)₃. Both the catalytic systems exhibited high activity toward the homopolymerization of NB (as high as 2.7 × 10⁵ g_polymer/mol_Ni h, for Ni(II)/B(C₆F₅)₃ and 2.1 × 10⁵ g_polymer/mol_Pd h for Pd(II)/B(C₆F₅)₃, respectively.). Although the Pd(II)/B(C₆F₅)₃ shows very lower activity toward the copolymerization of NB with NB-OCOCH₃, Ni(II)/B(C₆F₅)₃ shows a high activity and produces the addition-type copolymer with relatively high molecular weights (MWs; 1.80–2.79 × 10⁵ g/mol) as well as narrow MW distribution (1.89–2.30). The NB-OCOCH₃ content in the copolymers can be controlled up to 5.8–12.0% by varying the comonomer feed ratios from 10 to 50%. The copolymers exhibited high transparency, high glass transition temperature (T_g > 263.9 °C), better solubility, and mechanical properties compared with the homopolymer of NB. The reactivity ratios of the two monomers were determined to be r_NB-OCOMe = 0.08, r_NB = 7.94 for Ni(II)/B(C₆F₅)₃ system, and r_NB-OCOMe = 0.07, r_NB = 6.49, for Pd(II)/B(C₆F₅)₃ system by the Kelen-Tüdõs method. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Copolymerization of norbornene (NB) with methoxycarbonylnorbornene (NB-COOCH₃) was carried out with catalytic system of Ni{CF₃C(O)CHC[N(naphthyl)]CH₃}₂ and B(C₆F₅)₃ in toluene. The catalytic system exhibited higher activity 2.69 × 10⁵ (gpolymer/mol Ni h) for copolymerization of norbornene and methoxycarbonylnorbornene. The influence results of the comonomer feed content on the polymerization showed that the NB-COOCH₃ has a very high insertion ratio in all copolymers, and the NB-COOCH₃ content in copolymers can be controlled to be 7.9–77.6 mol % at content of 10–90 mol % of the NB-COOCH₃ in the monomer feeds ratios. The reactivity ratios, r_NB-COOCH3 = 0.578 and r_NB = 0.859, were determined by the Kelen–TÜdÕs method. Copolymers were processed by solution casting method, dry/wet phase inversion technique, and electrospinning. The films prepared by solution casting method showed good transparency in the visible region. The membranes processed by dry/wet phase inversion technique were microporous structures. The fibers diameters fabricated by electrospinning were about 3 μm. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Novel liquid-crystalline alternating conjugated copolymers [P(P(6)CN-alt-Cz) and P(P(6)CN-alt-MeP)] with phenylene and carbazolylene or phenylene with methyl substitution onto the main chain have been synthesized through palladium-catalyzed Suzuki coupling reactions. The influence of the incorporation of carbazolylene and the substituted phenylene into the main chain on the thermal, mesomorphic, and luminescent properties has been investigated by Fourier transform infrared spectroscopy, thermogravimetry, differential scanning calorimetry, polarized optical microscopy, ultraviolet–visible spectroscopy, photoluminescence (PL), and cyclic voltammetry. These polymers show highly thermal stability, losing little of their weights when heated to 360 °C. The conjugated copolymers exhibit liquid crystallinity at elevated temperature. The existence of the chromophoric terphenyl core endows the copolymers with high PL and the polymer P(P(6)CN-alt-Cz containing carbazolylene unit can emit more pure blue light. All the copolymer films with low band gaps about 2.3–2.4 eV undergo reversible oxidation and reduction processes, significantly lower than the band gap of poly(p-phenylene). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 434–442, 2010

Mesogen jacketed liquid crystalline poly(1-alkyne) and poly(1-phenyl-1-alkyne) linked pendants of terphenyl mesogens with hexyloxy tails at the waist position ({RCC [(CH₂)₃OOC-terpheyl-(OC₆H₁₃)₂]}_n, where RH, PHATP(OC6)2; RC₆H₅, PPATP(OC6)2) were synthesized. The influences of structural variations on the thermal, mesomorphic, and luminescent properties were investigated. Polymerizations of all monomers are carried out by WCl₆-Ph₄Sn catalysts successfully. The polymers are stable (T_d ≥ 340 °C) and soluble in common solvents. The monomers and polymers show enantiotropic SmA phases in the heating and cooling processes, and the lateral side chains of the mesogenic units are perpendicular to the main chain. The “jacket effect” of chromophoric terphenyl core “shell” around the main chain also contributes to polymers with high photoluminescence, and the pendant-to-backbone energy transfer path is involved in the luminescence process of this polymers. In comparison with monosubstituted polyacetylene PHATP(OC6)2, the disubstituted polyacetylene PPATP(OC6)2 shows better photoluminescence in both THF solution and film, and exhibited about 40 nm red-shifted than PHATP(OC6)2, indicating that the “jacket effect” of terphenyl mesogens forces poly(1-phenyl-1-alkyne) backbone to extend in a more planar conformation with a better conjugation. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

The poly(ethylene terephthalate-co-ethyleneoxide-co-DL-lactide) copolymers were successfully prepared by the melt reaction between poly(ethylene terephthalate), poly(ethylene glycol), and DL-oligo(lactic acid) without any catalysts. The transesterification between ethylene terephthalate, ethyleneoxide, and lactide segments during the reaction was confirmed by the ¹H NMR analysis. The effect of reaction temperatures and the starting feed ratios on the molecular microstructures, molecular weights, solubility, thermal properties, and degradability of the copolyesters was extensively studied. The values of crystallization temperature, melting temperature, crystallization, and melting enthalpy of the copolyesters were found to be influenced by the reaction temperatures, starting feed ratios, etc. The copolyesters showed good tensile properties and were found to degrade in the soil burial experiments during the period of 3 months. The morphology of the copolyester films were also investigated by scanning electron microscopy during soil burial degradation. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

Vinyl-type copolymerization of norbornene (NBE) and 5-NBE-2-yl-acetate (NBE-OCOMe) in toluene were investigated using a novel homogeneous catalyst system based on bis(β-ketonaphthylamino)Ni(II)/B(C₆F₅)₃/AlEt₃. The copolymerization behavior as well as the copolymerization conditions, such as the levels of B(C₆F₅)₃ and AlEt₃, temperature, and monomer feed ratios, which influence on the copolymerization were examined. Without combination of AlEt₃, the catalytic bis(β-ketonaphthylamino)Ni(II)/B(C₆F₅)₃ exhibited very high catalyst activity for polymerization of NBE. Combination of AlEt₃ in catalyst system resulted in low conversion for polymerization of NBE. For copolymerization of NBE and NBE-OCOMe, involvement of AlEt₃ in catalyst is necessary. Slight addition of NBE-OCOMe in copolymerization of NBE and NBE-OCOMe gives rise to significant increase of catalyst activity for catalytic system bis(β-ketonaphthylamino)Ni(II)/B(C₆F₅)₃/AlEt₃. Nevertheless, excess increase of the NBE-OCOMe content in the comonomer feed ratios results in decrease of conversion as well as activity of catalyst. The achieved copolymers were confirmed to be vinyl-addition copolymers through the analysis of FTIR, ¹H NMR, and ¹³C NMR spectra. ¹³C NMR studies further revealed the composition of the copolymer and the incorporation rate was 7.6–54.1 mol % ester units at a content of 30–90 mol % of the NBE-OCOMe in the monomer feeds ratios. TGA analysis results showed that the copolymer exhibited good thermal stability (T_d > 410 °C) and failed to observe the glass transitions temperature over 300 °C. The copolymers are confirmed to be noncrystalline by WAXD analysis results and show good solubility in common organic solvents. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3990–4000, 2009

Series of poly(p-phenylene)s (PPPs) containing terphenyl mesogenic pendants with cyano and methoxy terminal groups by flexible COO(CH₂)₆O bridge [P(CN) and P(OCH₃)] are synthesized through Yamamoto polycondensation with Ni-based complex catalysts. The effects of the structural variation on their properties, especially their mesomorphism, ultraviolet–visible (UV), and photoluminescence behaviors, are studied. All of the polymers are stable, losing little of their weights when heated to ≥340 °C. The polymers show good solubility and can be dissolved in common solvents. P(CN) with cyano terminal group shows enantiotropic SmA_d phase with bilayer packing arrangement, while P(OCH₃) with methoxy terminal group readily forms nematic and SmA_d phase when heated and cooled. Photoexcitation of their solutions induces strong blue light emission. Compared with P(OCH₃), the light-emitting bands of polymer P(CN) is slightly redshifted to 428 nm and the emission intensity of P(CN) is much stronger, due to the existence of donor–acceptor pairs. More interestingly, both of the polymers exhibit obvious Cotton effect on the CD spectra, resulting from the predominant screw sense of the backbone. This indicates that the bulky mesogenic pendant orientating around the backbone will force the main chain with helical conformation in the long region due to steric crowdedness. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4723–4735, 2009

A reactive blend of poly(ethylene glycol) (PEG) and DL-oligo(lactic acid) (OLA) is obtained at high temperature to produce partial PEG/OLA multiblock copolymer without purification. The reactive blend of PEG and OLA easily reacts with poly(1,4-butylene terephthalate) (PBT) in the melt leading to the formation of high-molar mass poly(1,4-butylene terephthalate-co-ethylene oxide-co-DL-lactide) (PBTEOLA) copolymers. The analysis from ¹H NMR and solubility test reveals that the transesterification between butylene terephthalate (BT), ethyleneoxide (EO), and lactide (LA) segments during synthesis is unavoidable. The copolyesters are segmented copolyesters with certain random properties, as confirmed by their thermal behavior. The copolyesters show only one melting temperature (T_m) on the second heating run and one crystallization temperature (T_c) on the cooling cycle from differential scanning calorimetry measurement. With increase of OLA feeding composition in PEG/OLA blend or increase of content of PEG/OLA blend, the T_m and T_c of copolyesters decrease, and solubility increases. The conventional size-exclusion chromatography polystyrene calibration estimates weight-averaged molecular weight of the copolyester to be as high as 66,600 g/mol. Mechanical tests indicate that the copolyesters exhibit high Young's modulus of 50–100 MPa and good elongation at break of 32–137%. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008