Co-reporter:Dr. Shuai He; Meizhen Qu ; Yujun Feng
ChemNanoMat 2015 Volume 1( Issue 6) pp:438-444
Publication Date(Web):
DOI:10.1002/cnma.201500070
Abstract
The low dispersibility of graphene in water, given its hydrophobic nature, is considered a serious problem that limits its use. Here, we describe a method to stably disperse graphene using a dispersant containing a tertiary amine and a pyrene group. The dispersant modifies the graphene surface via π–π stacking, allowing it to be dispersed in water. The dispersant undergoes a hydrophobic–hydrophilic transition upon being stimulated by CO2 and N2, exhibiting a faster response (reaction time of 1.5 min) and lower recovery temperature (40 °C) than those of compounds with amidine-like structures. We found that the graphene modified by this gas-sensitive dispersant exhibited reversible dispersion/aggregation behavior upon the bubbling/removal of CO2. The proposed method is a simple one for the reversible dispersion/aggregation of graphene by stimulating it with a gas and should be suitable for fabricating sensors, drug-delivery systems, “smart” surfaces, and switching devices.
Co-reporter:Yufeng Wu;Zanru Guo
Colloid and Polymer Science 2014 Volume 292( Issue 2) pp:281-289
Publication Date(Web):2014 February
DOI:10.1007/s00396-013-3068-9
Single-walled carbon nanotubes (SWNTs) were dispersed in pure water with a thermo-responsive amphiphilic PNIPAM150-F108-PNIPAM150 pentablock terpolymer in comparison with its precursor PEO136-PPO45-PEO136 (F108) triblock copolymer. The stability, dispersibility, and thermo-responsive behaviors of the polymer/SWNT hybrids were characterized by UV–vis–NIR spectroscopy, thermal gravimetric analysis, viscosity measurement, Raman spectroscopy, and high-resolution transmission electron microscopy. The pentablock/SWNT hybrids showed superior ability in stabilization over F108/SWNT hybrids, and no sign of sedimentation was found at room temperature for 6 weeks or even 2 months of storage. The pentablock terpolymer can efficiently disperse SWNTs into individual tubes or small bundles with average diameter of about 5 nm, and their chains were helically wrapped onto the nanotube surface, whereas the larger bundles of the nanotubes with sizes of 15–25 nm were observed in F108/SWNT hybrids. Moreover, the pentablock/SWNT hybrids switched reversibly between the well-exfoliated and the aggregated states when cyclically increasing and decreasing temperature.
Co-reporter:Zonglin Chu, Cécile A. Dreiss and Yujun Feng
Chemical Society Reviews 2013 vol. 42(Issue 17) pp:7174-7203
Publication Date(Web):02 Apr 2013
DOI:10.1039/C3CS35490C
A major scientific challenge of the past decade pertaining to the field of soft matter has been to craft ‘adaptable’ materials, inspired by nature, which can dynamically alter their structure and functionality on demand, in response to triggers produced by environmental changes. Amongst these, ‘smart’ surfactant wormlike micelles, responsive to external stimuli, are a particularly recent area of development, yet highly promising, given the versatility of the materials but simplicity of the design—relying on small amphiphilic molecules and their spontaneous self-assembly. The switching ‘on’ and ‘off’ of the micellar assembly structures has been reported using electrical, optical, thermal or pH triggers and is now envisaged for multiple stimuli. The structural changes, in turn, can induce major variations in the macroscopic characteristics, affecting properties such as viscosity and elasticity and sometimes even leading to a spontaneous and effective ‘sol–gel’ transition. These original smart materials based on wormlike micelles have been successfully used in the oil industry, and offer a significant potential in a wide range of other technological applications, including biomedicine, cleaning processes, drag reduction, template synthesis, to name but a few. This review will report results in this field published over the last few years, describe the potential and practical applications of stimuli-responsive wormlike micelles and point out future challenges.
Co-reporter:Zanru Guo;Shuai He;Meizhen Qu;Honglin Chen;Hanbin Liu;Yufeng Wu;Yu Wang
Advanced Materials 2013 Volume 25( Issue 4) pp:584-590
Publication Date(Web):
DOI:10.1002/adma.201202991
Co-reporter:Yongmin Zhang, Yujun Feng, Jiyu Wang, Shuai He, Zanru Guo, Zonglin Chu and Cécile A. Dreiss
Chemical Communications 2013 vol. 49(Issue 43) pp:4902-4904
Publication Date(Web):08 Apr 2013
DOI:10.1039/C3CC41059E
A wormlike micellar system that undergoes a fully reversible, repeatable “sol–gel” transition upon alternative treatment with CO2 and N2 has been developed based on a C18-tailed polyamine surfactant.
Co-reporter:Zonglin Chu and Yujun Feng
ACS Sustainable Chemistry & Engineering 2013 Volume 1(Issue 1) pp:75
Publication Date(Web):October 8, 2012
DOI:10.1021/sc300037e
There is no doubt that the surfactant and detergent industry is facing increasing severe environmental impact, and environmentally benign pathways are preferred to prepare these materials. We report herein a green route toward the preparation of vegetable-derived long-chain surfactants. The synthesis process possesses the following characteristics: bioresource-derived erucic acid (leftovers of rapeseed oil) was used as a starting material; no solvent was used and no chemical waste was produced; and high-yield products could be obtained in short reaction time. Compared with traditional surfactants bearing a saturated hydrophobic tail shorter than C18, the erucic acid-derived surfactants are more environmentally friendly because of their lower dosages in practical applications and the presence of the chemical degradable unsaturated bond and amido group in their molecular architecture.Keywords: Biomass; Green chemistry; Modified amidation reaction; No-solvent synthesis; Vegetable-derived surfactants
Co-reporter:Yongmin Zhang, Yixiu Han, Zonglin Chu, Shuai He, Jichao Zhang, Yujun Feng
Journal of Colloid and Interface Science 2013 Volume 394() pp:319-328
Publication Date(Web):15 March 2013
DOI:10.1016/j.jcis.2012.11.032
A novel pH-switchable anionic wormlike micellar system has been developed by simply changing pH value of natural erucic acid solutions without needing specialized organic synthesis or addition of hydrotropes. Through rheology, optical transmittance, and cryo-TEM observation, it was found that at 60 °C, the 100 mM erucic acid solutions transform from low viscous emulsion-like fluids to viscoelastic hydrogels when the pH is increased from 8.03 to 12.35, and when the pH is cycled between 9.02 and 12.35, the viscosity of the solutions varies correspondingly between 2 and 200,000 mPa s, five orders of magnitude in viscosity range. Such a reversible switch can be easily cycled more than four times without any deterioration. In addition, when the pH is fixed between 9.0 and 12.35, the solutions shift to highly elastic solid-like gels with decreasing temperature. These pH-switchable and temperature-sensitive rheological properties are attributed to the presence of carboxylic groups in the erucic acid molecules. With increasing pH, erucic acid is converted into an anionic surfactant, sodium erucate, which self-assembles into aggregates evolving from spherical micelles to wormlike micelles; when temperature is decreased, these disordered micellar structures become highly ordered under the effect of crystallization of hydrophobic erucate chains, forming opaque solid-like hydrogels.Graphical abstractHighlights► A pH-switchable anionic wormlike micellar system based only on natural renewable erucic acid has been developed. ► The system can be easily prepared by adding NaOH and is responsive in alkaline conditions. ► Thermally induced transitions from fluid-like solutions to solid-like hydrogels have been investigated. ► Thermally induced structural transitions from fluids to hydrogels with pH-switchable anionic wormlike micelles.
Co-reporter:Yongmin Zhang, Zonglin Chu, Cécile A. Dreiss, Yuejiao Wang, Chenhong Fei and Yujun Feng
Soft Matter 2013 vol. 9(Issue 27) pp:6217-6221
Publication Date(Web):20 May 2013
DOI:10.1039/C3SM50913C
A CO2-switchable wormlike micellar system was fabricated using N-erucamidopropyl-N,N-dimethylamine without any hydrotropes. Its viscoelasticity varies by five orders of magnitude when cyclically bubbling CO2 and air at ambient temperature and pressure without the need for heating, reflecting changes in aggregate morphology from entangled worms to spherical micelles.
Co-reporter:Quansheng Chen;Yu Wang;Zhiyong Lu
Polymer Bulletin 2013 Volume 70( Issue 2) pp:391-401
Publication Date(Web):2013/02/01
DOI:10.1007/s00289-012-0798-7
Polymer flooding represents one of the most efficient processes to enhance oil recovery, but the poor thermostability and salt tolerance of the currently used water-soluble polymers impeded their use in high temperature and salinity oil reservoirs. Thermoviscosifying polymers (TVPs) whose viscosity increases upon increasing temperature and salinity may overcome the deficiencies of most water-soluble polymers. A novel TVP was studied in comparison with traditional partially hydrolyzed polyacrylamide (HPAM) in synthetic brine regarding their rheological behaviors and core flooding experiments under simulated high temperature and salinity oil reservoir conditions (T: 85 °C, and total salinity: 32,868 mg/L, [Ca2+] + [Mg2+]: 873 mg/L). It was found that with increasing temperature, both apparent viscosity and elastic modulus of the TVP polymer solution increase, while those of the HPAM solutions decrease. Such a difference is attributed to their microstructures formed in aqueous solution, which were observed by cryogenic transmission electron microscopy. Core flow tests at equal conditions showed an oil recovery factor of 13.5 % for the TVP solution versus only 2.1 % for the HPAM solution.
Co-reporter:Yufeng Wu;Dingwei Zhu;Zanru Guo
Journal of Polymer Science Part B: Polymer Physics 2013 Volume 51( Issue 18) pp:1335-1342
Publication Date(Web):
DOI:10.1002/polb.23343
ABSTRACT
Thermo-reversible phase behaviors and rheological properties of a pentablock terpolymer solution, poly(N-isopropylacrylamide)-b-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(N-isopropylacrylamide) (PNIPAM150-PEO136-PPO45-PEO136-PNIPAM150), are investigated in comparison with its precursor, PEO136-PPO45-PEO136 (F108). It is found that the critical gelation concentration of the terpolymer solution is only about 11 wt %, which is significantly lower than that of F108 solution (∼22 wt %). The 11 wt % terpolymer solution displays higher viscosity, stronger gel strength, and fast thermo-responsive behavior compared with the 22 wt % F108 solution. The 11 wt % terpolymer solution shows a typical Newtonian fluid behavior at 30 °C due to the presence of individual spherical micelles, and presents an elastic gel property at 41 °C because of the formation of the close-packed micelle aggregates. Cryogenic transmission electron microscopy (cryo-TEM) and variable-temperature 1H NMR results demonstrate that the sol–gel phase transition mechanism is mainly related to the hydrophilic/hydrophobic transition of PPO and PNIPAM groups by external temperature stimulus. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1335–1342
Co-reporter:Shuai He, Honglin Chen, Zanru Guo, Biqing Wang, Chongli Tang, Yujun Feng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 429() pp:98-105
Publication Date(Web):20 July 2013
DOI:10.1016/j.colsurfa.2013.03.068
•High-content silver colloid stabilized by a gemini surfactant was reported for the first time.•Gemini surfactant can produce high-concentration and stable silver nanoparticles.•The nanoparticles exhibit good catalytic activity for reduction of 4-nitrophenol.•It can be extended to the preparation of other high-concentration metal colloid.Silver nanoparticles have been intensively investigated in recent years due to their unique physical and chemical properties. However, the low concentration and poor stability of silver nanoparticles in aqueous solution limit their wide applications. In this work, the cationic gemini surfactant dimethylene-1,2-bis(dodecyl dimethylammonium bromide) (12-2-12) was employed to prepare and stabilize high-concentration silver nanoparticle, in comparison with its monomeric counterpart, dodecyl trimethyl ammonium bromide (DTAB). The size, size distribution and long-term stability of silver nanoparticles were examined by means of transmission electron microscopy and UV–vis spectrophotometry. It was found that when using 12-2-12 as the stabilizer, the concentration of silver nanoparticles in aqueous solution can reach 44.6 mM, and the average size was 11 ± 3 nm, much higher concentration and much narrower size distribution than those (35.7 mM, 15 ± 10 nm) with DTAB as the stabilizer. Silver nanoparticles stabilized by 12-2-12 show better long-term stability that those stabilized by DTAB. Negative staining TEM observation proved the 12-2-12 molecule had more stable and more efficient capping ability to stabilize silver nanoparticles than DTAB due to its double-head architecture and high charge density. The as-obtained nanoparticles stabilized by 12-2-12 also displayed good catalytic activity for the reduction of 4-nitrophenol.
Co-reporter:Yongmin Zhang, Yeyuan Luo, Yuejiao Wang, Jichao Zhang, Yujun Feng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 436() pp:71-79
Publication Date(Web):5 September 2013
DOI:10.1016/j.colsurfa.2013.06.016
•Single-component wormlike micelles formed by a saturated C22-tailed betaine.•Lower overlapping concentration than its monounsaturated counterparts.•Better stability at high temperature.C22-tailed surfactants have aroused considerable attention due to their strong tendency to self-assemble into wormlike micelles, but most of these amphiphilies were prepared from erucic acid whose mono-unsaturated hydrophobic tail is readily degraded at high temperature. Here we report for the first time the wormlike micelles formed from a sole carboxylbetaine surfactant with a saturated C22-tail, docosyl dimethyl carboxylbetaine (DDCB), and examined its aqueous solution properties through UV–vis spectroscopy, surface tension, rheology and cryo-TEM observation. Above its Krafft temperature (59.5 °C) and overlapping concentration (∼0.68 mM), DDCB aqueous solution displays unusually strong viscoelasticity without needing any specialized hydrotropes that are normally necessary in conventional wormlike micellar systems. Cryo-TEM observation confirmed the coexistence of wormlike micelles and viscles, in good agreement with the prediction from “packing parameter” theory. Compared with its unsaturated counterparts, DDCB worms show lower overlapping concentration, longer breaking time, better stability at high temperature and ease of preparation due to the “single-component” character.
Co-reporter:Yongmin Zhang, Yujun Feng, Yuejiao Wang, and Xiangliang Li
Langmuir 2013 Volume 29(Issue 13) pp:4187-4192
Publication Date(Web):March 20, 2013
DOI:10.1021/la400051a
Recent research has highlighted a growing focus on stimuli-responsive surfactant wormlike micelles (WLMs), particularly those with switchability. Here we report CO2-switchable WLMs based on the commercial anionic surfactant sodium dodecyl sulfate (SDS) and N,N,N′,N′-tetramethyl-1,3-propanediamine (TMPDA) mixed in a mole ratio of 2:1. When CO2 is bubbled into an aqueous mixture of these reactants, the TMPDA molecules are protonated to form quaternary ammonium species, two of which in the same protonated TMPDA molecule “bridge” two SDS molecules by noncovalent electrostatic attraction, behaving like a pseudogemini surfactant and forming viscoelastic WLMs as verified by cryo-TEM. Upon removal of CO2, the quaternized spacers are deprotonated back to tertiary amines, dissociating the pseudogeminis back to conventional SDS molecules that form low-viscosity spherical micelles. Such a reversible sphere-to-worm transition could be repeated several cycles without a loss of response to CO2.
Co-reporter:Yufeng Wu;Shuai He;Zanru Guo
Polymer Science, Series B 2013 Volume 55( Issue 11-12) pp:634-642
Publication Date(Web):2013 November
DOI:10.1134/S1560090413130058
Thermo-reversible silver nanoparticles (Ag-NPs) were prepared by the sodium borohydride reduction of silver nitrate (AgNO3) in the presence of a pentablock terpolymer, poly(N-isopropylacrylamide)-b-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(N-isopropylacrylamide) (PNIPAM150-PEO136-PPO45-PEO136-PNIPAM150). The pentablock terpolymer-stabilized silver nanoparticles (Pentablock-S-Ag) were characterized by UV-VIS spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM). At temperatures below lower critical solution temperature (LCST) of Pentablock-S-Ag solutions, the obtained Ag-NPs are well-dispersed with spherical shape, and their sizes mainly depend upon the molar ratios of pentablock terpolymer to AgNO3; at temperatures above LCST, the size of Ag-NPs decreases and their aggregates are observed due to the collapse and shrinkage of the thermo-responsive PNIPAM and PPO segments. A reversible dispersion-aggregation process upon recyclically changing temperature is also observed.
Co-reporter:Shuai He, Biqing Wang, Honglin Chen, Chongli Tang, and Yujun Feng
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 4) pp:2116
Publication Date(Web):March 12, 2012
DOI:10.1021/am300094f
Iodine is an effective, simple, and inexpensive bactericide in disinfection. However, the poor solubility and stability of iodine in water limit its applications. In addition, the active iodine content in the commercial iodophors is quite low, and the reported triiodide complex is unstable. In this work, a long-term stable triiodide complex antimicrobial system was prepared by mixing iodine and a cationic gemini surfactant into lauryldimethylamine oxide (LDAO) aqueous solution, and its stability was examined by means of UV–vis spectrophotometry. It was found that the content of LDAO, cationic gemini surfactant and H2SO4 played crucial roles in stabilizing antimicrobial system, and the active iodine (i.e., triiodide complex) content of the optimum formulation can remain stable for 150 days, as iodine is encapsulated by the mixed vesicles assembled by the protonated LDAO and the added gemini surfactant. However, the active iodine reduced rapidly when NaCl was added or the pH was increased in the environment. Furthermore, the antimicrobial efficacy of the optimized formulation was studied against Candida albicans, and more than 4 log reduction in viable cell after 5 min of contact was obtained.Keywords: cryo-TEM; fungicide; gemini surfactant; long-term stability; mixed micelles; triiodide complex;
Co-reporter:Yixiu Han, Zonglin Chu, Huanquan Sun, Zhenquan Li and Yujun Feng
RSC Advances 2012 vol. 2(Issue 8) pp:3396-3402
Publication Date(Web):28 Feb 2012
DOI:10.1039/C2RA20136D
In such application fields as oilwell stimulation, tertiary oil recovery and drug release, environmental-friendly wormlike micelles are largely preferred. The present work reports a “green” wormlike micellar system formed by a bio-based anionic surfactant, sodium erucate (NaOEr), and a biodegradable hydrotrope, choline. The micellar solutions were examined by means of rheology and cryo-TEM observation. Besides possessing lower toxicity, choline exhibits a stronger ability to induce micelle growth than tetramethylammonium, which is commonly used to promote the formation of anionic worms, and the choline–NaOEr system is more thermosensitive with increasing counterion concentration. These notable advantages enable the choline–NaOEr wormlike micellar system to find potential applications in biomedical areas and clean fracturing fluids.
Co-reporter:Yufeng Wu;Xingli Liu;Yu Wang;Zanru Guo
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 14) pp:1489-1498
Publication Date(Web):
DOI:10.1002/macp.201200106
Abstract
A series of thermoresponsive pentablock terpolymers, poly(N-isopropylacrylamide)-b-poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(N-isopropylacrylamide), is prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization. The effect of NIPAM and PPO block lengths on lower critical solution temperature (LCST), critical micelle concentration (cmc), and aggregation number (Nagg) is investigated via UV–Vis spectroscopy and steady-state fluorescence spectroscopy. The results show that upon increasing the block lengths, LCST and cmc decrease, while Nagg increases. TEM observation shows that associated spherical-like particles are evidenced below the LCST of the terpolymers, and regular or irregular spherical micelles or even intermicellar aggregates are observed above the LCST.
Co-reporter:Dan Feng;Yongmin Zhang;Quansheng Chen;Jiyu Wang
Journal of Surfactants and Detergents 2012 Volume 15( Issue 5) pp:657-661
Publication Date(Web):2012 September
DOI:10.1007/s11743-012-1359-7
Recent studies have shown that the surfactants bearing an ultra-long hydrophobic chain (>C18) exhibit unique self-assembly properties. However, their synthesis and surface activities have been less documented. In this work, monounsaturated alkyl dimethyl amidopropyl betaines, UCnDAB (n = 18, 22, and 24), were prepared by the reaction of the corresponding fatty acids with N,N-dimethyl-1,3-propanediamine, followed by quaternization with sodium choloroacetate of the obtained intermediates. The intermediates and final surfactants were characterized by 1H NMR and ESI-HRMS, respectively. Krafft temperature (TK) and surface activities of the surfactants were also examined. It was found that TK of all these surfactants is lower than 0 °C, and their critical micellar concentration (CMC) is within the range of 10−3 mmol/L. In addition, the linear relationship between lg CMC and n is still in evidence.
Co-reporter:Zonglin Chu and Yujun Feng
Langmuir 2012 Volume 28(Issue 2) pp:1175-1181
Publication Date(Web):December 7, 2011
DOI:10.1021/la204316g
Long-chain amidosulfobetaine surfactants, 3-(N-fattyamidopropyl-N,N-dimethyl ammonium) propanesulfonates (n-DAS, n > 18), are insoluble in pure water due to their high Krafft temperature (TK), while they are soluble when inorganic salt is added to the surfactant solution as the TK of these zwitterionic surfactants is decreased. The influence of the salt content and ionic species of the added electrolytes on the TK of the series of amidosulfobetaine surfactants was examined by means of UV–vis spectrophometry and visual inspection. It was found that the TK of these surfactants depends strongly on not only the hydrophobic alkyl length (n), but also the salinity of the aqueous environment. When the salt concentration is increased from 0 to 100 mM, the TK shows a sharp decrease; when the salinity is fixed between 100 and 2000 mM, the TK varies linearly with n with a slope of ∼7.7 irrespective of the salt species and the salt content. When the salt concentration is further increased above 2000 mM, a linear function is still observed, but the slope increases slightly.
Co-reporter:Zanru Guo, Yujun Feng, Yu Wang, Jiyu Wang, Yufeng Wu and Yongmin Zhang
Chemical Communications 2011 vol. 47(Issue 33) pp:9348-9350
Publication Date(Web):18 Jul 2011
DOI:10.1039/C1CC12388B
An amidine-based polymer was prepared by combination of RAFT polymerization and “click” reaction, and the polymer undergoes a hydrophobic−hydrophilic transition upon the stimulus of CO2.
Co-reporter:Zonglin Chu and Yujun Feng
Chemical Communications 2011 vol. 47(Issue 25) pp:7191-7193
Publication Date(Web):04 May 2011
DOI:10.1039/C1CC11428J
A thermo-switchable surfactant gel with the property of gelation on heating was developed for the first time based on palmitylamidosulfobetaine. Micellar growth from globular aggregates to entangled worms upon heating is responsible for the thermal gelation.
Co-reporter:Yixiu Han, Yujun Feng, Huanquan Sun, Zhenquan Li, Yugui Han, and Hongyan Wang
The Journal of Physical Chemistry B 2011 Volume 115(Issue 21) pp:6893-6902
Publication Date(Web):May 5, 2011
DOI:10.1021/jp2004634
Anionic wormlike micelles, particularly those formed by long-chain carboxylate surfactants, are relatively less documented though their cationic or zwitterionic counterparts are frequently reported. In this study, the wormlike micelles of sodium erucate (NaOEr), a C22-tailed anionic surfactant with a monounsaturated tail, in the presence of a tetraalkylammonium hydrotrope were investigated for the first time. The different effects of two hydrotropes, benzyl trimethyl ammonium bromide (BTAB) and tetramethyl ammonium bromide (TMAB), on the phase behavior and rheological behaviors were compared, and the influences of surfactant concentration and temperature on the rheological properties of NaOEr solutions were also examined. Both organic salts can lower the Krafft temperature of NaOEr solutions and thus improve its water solubility, but BTAB can make TK drop more sharply. At a fixed NaOEr concentration, less BTAB is demanded to induce the formation of viscoelastic solution and to obtain the maximum viscosity of NaOEr solution; at a constant salt concentration, with increasing NaOEr content, the NaOEr–BTAB system shows a larger zero-shear viscosity (η0), relaxation time, and plateau modulus but lower overlapping concentration than those of the NaOEr–TMAB system. The occurrence of maximum η0 with increasing salt content for the NaOEr–BTAB system results from the formation of vesicles and L3 phases, which were verified by cryo-TEM observations. η0 shows an exponential decrease with increasing temperature; nevertheless it still remains above 103 mPa·s even at 90 °C.
Co-reporter:Xin Su;Biqing Wang;Zhiyong Lu;Limin Wei
Colloid and Polymer Science 2011 Volume 289( Issue 1) pp:101-110
Publication Date(Web):2011 January
DOI:10.1007/s00396-010-2331-6
A series of oligomeric cationic surfactants were prepared directly in aqueous media by atom transfer radical polymerization (ATRP) of methacrylate surfmers. The molecular weight of oligomeric surfactants was characterized by 1H NMR, and the results were close to those obtained via GPC analysis. The resulting oligomers have narrow molecular weight distributions, with polydispersity indices in the range of 1.18–1.32, and the research indicated that the synthesis of the oligomeric surfactants was consistent with characteristics of controlled free radical polymerization. The surface activities of oligomeric surfactant solutions were examined, and it was found that their surface activities were enhanced when increasing oligomerization degree or hydrophobic chain length, in agreement with what observed for oligomeric surfactants prepared by classic organic synthesis. Spherical vesicles formed by these oligomers prepared via ATRP were observed by Cryo-TEM. It was proved that ATRP possesses the advantages over classic organic synthesis, as it provided a simple and easy route for synthesizing oligomeric surfactants with well-controlled architecture.
Co-reporter:Xin Su;Biqing Wang;Zhiyong Lu;Limin Wei
Journal of Surfactants and Detergents 2011 Volume 14( Issue 1) pp:73-76
Publication Date(Web):2011 January
DOI:10.1007/s11743-010-1211-x
A new cationic gemini surfmer (polymerizable surfactant or surface-active monomer) with an acrylic reactive group in its spacer group was synthesized and characterized, and its surface activity properties were examined in comparison with its intermediate surfactant 12-3OH-12·2Cl−, a previously-reported gemini surfmer 12′-2-12′·2Br−, as well as monomeric surfactant dodecyl trimethylammonium bromide. It was found that neither the incorporation of a double bond onto the gemini surfactant nor the change of location of the double bond will affect surface activities of the gemini surfactant.
Co-reporter:Xingli Liu;Xiaolan Li;Zhiyong Lu;Xinping Miao
Journal of Polymer Research 2011 Volume 18( Issue 5) pp:897-905
Publication Date(Web):2011 September
DOI:10.1007/s10965-010-9487-0
A novel family of acrylic acid-based superabsorbent polymers (SAP-n) with controlled-absorption rate were synthesized via aqueous solution polymerization using K2S2O8/NaHSO3 as the redox initiators, N, N'-methylenebisacrylamide (NMBA) as the crosslinker, 2-methacryloyloxyethyl n-alkyl dimethyl ammonium bromide (CnDM, n = 4, 8, 12, 16) as the hydrophobic comonomers. The structures of the copolymers were elucidated by FT-IR and ionic chromatographic (IC) analysis respectively, and the swelling properties of the copolymers were examined. It was found that the water absorbency capacity either in distilled water or in 0.9% NaCl brine decreased with increasing hydrophobe length or content, and the water absorbency rate of SAP-n was as expected lower than that of SAP without hydrophobic monomer; in addition, water retention evaluation under different temperatures revealed that this kind of copolymers could absorb and retain large amount of water at room temperature and release it at high temperature.
Co-reporter:Zonglin Chu and Yujun Feng
Chemical Communications 2010 vol. 46(Issue 47) pp:9028-9030
Publication Date(Web):04 Nov 2010
DOI:10.1039/C0CC02415E
A novel pH-switchable wormlike micellar system was prepared by mixing N-erucamidopropyl-N,N-dimethylamine and maleic acid with molar ratio of 2:1. The viscosity of the micellar solution is switchable via tuning the pH through the addition of minor acid or base. Such a system possesses the characteristics of a facile, rapid, cost-effective reversible process and recyclable cheaper materials.
Co-reporter:Zonglin Chu and Yujun Feng
Soft Matter 2010 vol. 6(Issue 24) pp:6065-6067
Publication Date(Web):22 Oct 2010
DOI:10.1039/C0SM00874E
Wormlike micellar gels formed by concentrated 3-(N-erucamidopropyl-N,N-dimethyl ammonium) propanesulfonate (EDAS) solutions show both gel-like behavior and shear banding transitions. Such surfactant gels are strong viscoelastic fluids with ultra-long but finite relaxation time, instead of bulk gels with infinite zero-shear viscosity and relaxation time. We demonstrate for the first time the relationship between the yield stress and shear banding transition of the surfactant gels.
Co-reporter:Yu Wang;Biqing Wang;Zhiyong Lu
Journal of Applied Polymer Science 2010 Volume 116( Issue 6) pp:3516-3524
Publication Date(Web):
DOI:10.1002/app.31884
Abstract
A novel thermoviscosifying water-soluble polymer was synthesized by direct free radical copolymerization of acrylamide with a newly-prepared macromonomer, and its aqueous solution viscosity behavior at different temperatures was preliminarily examined in both pure water and KCl brine in comparison with its homopolyacrylamide counterpart. Thermoviscosifying ability of the copolymer was clearly evidenced in both aqueous media, and the thermoassociative temperature of the copolymer decreased upon increasing KCl content in polymer solution. Under the same conditions, homopolyacrylamide shows only thermothinning behavior and viscosity loss in both pure water and KCl solution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Zonglin Chu, Yujun Feng, Xin Su and Yixiu Han
Langmuir 2010 Volume 26(Issue 11) pp:7783-7791
Publication Date(Web):April 29, 2010
DOI:10.1021/la904582w
Wormlike micelles have been observed and explained in a wide variety of different types of surfactants except sulfobetaine ones. Here, we first report branched worms formed by a C22-tailed amidosulfobetaine surfactant—3-(N-erucamidopropyl-N,N-dimethyl ammonium) propane sulfonate (EDAS). Increasing EDAS concentration in the semidilute region increases the viscosity by several orders of magnitude and forms viscoelastic micellar solution of entangled and branched worms. The intermicellar branching is proved by rheological methods and Cryo-TEM observation. Besides, the rheological experiments indicate that EDAS worms show some advantages such as low overlapping concentration, insensitive to inorganic salt, stable over the whole pH range.
Co-reporter:Zhanfeng Xie
Journal of Surfactants and Detergents 2010 Volume 13( Issue 1) pp:
Publication Date(Web):2010 January
DOI:10.1007/s11743-009-1152-4
A series of alkylbetaine zwitterionic gemini surfactants, 1,2-bis[N-methyl-N-carboxymethyl-alkyl-ammonium]ethane (CnAb, n = 8, 10, 12, or 14), were synthesized by alkylation of N,N′-dimethylethylenediamine with an alkyl bromide, followed by reaction with sodium 2-bromoacetate. Their solution properties were characterized by surface tension, steady-state fluorescence, and rheological measurements. Surface-tension measurements showed CnAb had lower critical micelle concentration (CMC) and higher efficiency in lowering the surface tension than their corresponding monomeric surfactants. The logCMC of CnAb decreased linearly with increasing chain lengths up to 12. Viscosity measurements showed only C10Ab could enhance aqueous solution viscosity at high concentrations.
Co-reporter:Chenxin Xie;Weiping Cao;Houkai Teng;Jufeng Li;Zhiyong Lu
Journal of Applied Polymer Science 2009 Volume 111( Issue 5) pp:2527-2536
Publication Date(Web):
DOI:10.1002/app.29198
Abstract
Grafting copolymers of polyacrylamide (PAM) with Konjac gum (KGM) have been synthesized using ceric-ion-induced initiation technique. The copolymers were characterized using several instrumental techniques, including infrared (IR) spectroscopy, elementary analysis, scanning electron microscopy (SEM), size exclusion chromatography (SEC) analysis, and intrinsic viscosity to confirm the success of grafting. The flocculation performance of graft copolymers was characterized by two methods. One was to study the relationship between the flocculants doses in kaolin suspension and the supernatant transmittance, and the other is to examine the time dependence of sediment height of kaolin suspensions. It was found that the graft copolymer is better than KGM and pure PAM. Biodegradation behavior was testified by monitoring the decay of relative viscosities, and approved by KGM ether bonds breaking in IR spectra and the molecule weight reduction in SEC analysis. The results indicate that the grafted KGM copolymers have improved both, flocculation performance and better biodegradable properties than the unmodified parent KGM and pure PAM. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Hongsheng Lu;Zhiyu Huang
Journal of Applied Polymer Science 2008 Volume 110( Issue 3) pp:1837-1843
Publication Date(Web):
DOI:10.1002/app.28596
Abstract
This study was aimed at the association and effective hydrodynamic thickness of hydrophobically associating polyacrylamide (HAPAM) through porous media with coreflow experiment. It shows that there is strong hydrophobic association for HAPAM in porous media but not for polyacrylamide (PAM). The resistance factor and effective hydrodynamic thickness of HAPAM are obviously superior to those of PAM. HAPAM exhibits much stronger shear thinning behavior than PAM due to the ability to form transitional network structure. It also indicates that PAM can exhibit a transition from shear thinning behavior to shear thickening behavior at low polymer concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Zhi Chen;Dongliang Zhou;Puxin Zhu
Central European Journal of Chemistry 2008 Volume 6( Issue 3) pp:477-481
Publication Date(Web):2008 September
DOI:10.2478/s11532-008-0031-6
A series of new dimeric surfactants, twin-tailed gemini surfactants, 2(12)-s-2(12), were successfully prepared and characterized, and their monolayer films investigated by the measurement of surface pressure-area (π-A) and surface pressure-time (π-t) isotherms at the air/water interface by a Langmuir film balance. Compared to their monomeric counterparts, their collapse pressure (γcollapse) is smaller, whilst all the molecular area parameters are larger. The limited area (Alimited) and the initial area (Ainitial) of these twin-tailed gemini surfactants change with increasing spacer length s, and the surface pressure decreases with increasing time. It was also found that the higher the initial surface pressure, the larger the attenuation.
Co-reporter:Chenxin Xie, Yujun Feng, Weiping Cao, Yu Xia, Zhiyong Lu
Carbohydrate Polymers 2007 Volume 67(Issue 4) pp:566-571
Publication Date(Web):19 February 2007
DOI:10.1016/j.carbpol.2006.06.036
A series of phosphate-modified Konjac was synthesized by esterification of natural polysaccharide Konjac, and comparative studies were conducted to examine the flocculation efficiency and biodegradability for the modified and unmodified products. It is found that both modified derivatives and the unmodified parent show flocculation ability and biodegradability. However, within the polymer concentration studied, the higher the phosphoric content, the better the flocculation efficiency is, and the modified analogues show superior biodegradability to that of the parent polymer. The degradation mechanism was confirmed by IR spectrum that the P–O–P bond was cut during the aging process at 30 °C.
Co-reporter:Yuhai Sun, Yujun Feng, Hongwei Dong, Zhi Chen
Surface Science 2007 Volume 601(Issue 9) pp:1988-1995
Publication Date(Web):1 May 2007
DOI:10.1016/j.susc.2007.02.037
Co-reporter:Hongsheng Lu;Zhiyu Huang;Peiwu Li;Yong Ma;Hongsheng Lu;Zhiyu Huang;Peiwu Li;Yong Ma
Journal of Applied Polymer Science 2006 Volume 100(Issue 6) pp:4429-4433
Publication Date(Web):8 MAR 2006
DOI:10.1002/app.23119
To meet the needs for polymer particulates for the flooding of oil fields, a composite crosslinked copolymer of hydrophilic monomers [acrylamide (AM) and acrylic acid (AA)] and a hydrophobic monomer [methyl methacrylate (MMA)] was synthesized. In this study, we first added a rare-earth thermal stabilizer and inorganic montmorillonite (MMT) clay to the copolymer; this showed that the composite crosslinked copolymer exhibited good water-swelling performance at 200°C, with gel static grade of 5, a toughness index of 1.1170, and a salinity limit of 250,000 mg/L. It also had better injection abilities. The AM/AA/MMA ratio was 4 : 1 : 0.03 w/w, the crosslinker additive content was 0.03 wt %, the thermal stabilizer additive content was 5 wt %, and the clay (MMT) additive content was 13 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4429–4433, 2006
Co-reporter:Hongsheng Lu;Zhiyu Huang;Qaunsheng Chen;Jian Wang
Journal of Applied Polymer Science 2006 Volume 102(Issue 6) pp:5330-5335
Publication Date(Web):28 SEP 2006
DOI:10.1002/app.24885
The properties of two copolymeric particulates used for oilwell in-depth performance control were investigated systematically. The lab-scale studies showed that the average diameter of these particulates (E5 and G6) is 77.76 μm with the standard deviation of 2.16%. The two particulates exhibit good dilatability when immersed in 20 × 104 mg/L NaCl solution. Their capability of water retention (150 days) was 90% at 80°C. In addition, they exhibited good injectivity, driving performance and plug, and satisfied toughness index. The diffluence experiments confirmed that the coefficient of the profile modification were 85.7, 98.7, 86.1, and 98.1% when the permeability levels were 4.05 and 15.0, respectively. When using the two particulates, the average recovery ratio can reach 21%. The procedures mentioned earlier could be used as industry criteria to evaluate all kinds of particulate used as in-depth performance controllers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5330–5335, 2006
Co-reporter:Zonglin Chu and Yujun Feng
Chemical Communications 2011 - vol. 47(Issue 25) pp:NaN7193-7193
Publication Date(Web):2011/05/04
DOI:10.1039/C1CC11428J
A thermo-switchable surfactant gel with the property of gelation on heating was developed for the first time based on palmitylamidosulfobetaine. Micellar growth from globular aggregates to entangled worms upon heating is responsible for the thermal gelation.
Co-reporter:Zonglin Chu, Cécile A. Dreiss and Yujun Feng
Chemical Society Reviews 2013 - vol. 42(Issue 17) pp:NaN7203-7203
Publication Date(Web):2013/04/02
DOI:10.1039/C3CS35490C
A major scientific challenge of the past decade pertaining to the field of soft matter has been to craft ‘adaptable’ materials, inspired by nature, which can dynamically alter their structure and functionality on demand, in response to triggers produced by environmental changes. Amongst these, ‘smart’ surfactant wormlike micelles, responsive to external stimuli, are a particularly recent area of development, yet highly promising, given the versatility of the materials but simplicity of the design—relying on small amphiphilic molecules and their spontaneous self-assembly. The switching ‘on’ and ‘off’ of the micellar assembly structures has been reported using electrical, optical, thermal or pH triggers and is now envisaged for multiple stimuli. The structural changes, in turn, can induce major variations in the macroscopic characteristics, affecting properties such as viscosity and elasticity and sometimes even leading to a spontaneous and effective ‘sol–gel’ transition. These original smart materials based on wormlike micelles have been successfully used in the oil industry, and offer a significant potential in a wide range of other technological applications, including biomedicine, cleaning processes, drag reduction, template synthesis, to name but a few. This review will report results in this field published over the last few years, describe the potential and practical applications of stimuli-responsive wormlike micelles and point out future challenges.
Co-reporter:Zonglin Chu and Yujun Feng
Chemical Communications 2010 - vol. 46(Issue 47) pp:NaN9030-9030
Publication Date(Web):2010/11/04
DOI:10.1039/C0CC02415E
A novel pH-switchable wormlike micellar system was prepared by mixing N-erucamidopropyl-N,N-dimethylamine and maleic acid with molar ratio of 2:1. The viscosity of the micellar solution is switchable via tuning the pH through the addition of minor acid or base. Such a system possesses the characteristics of a facile, rapid, cost-effective reversible process and recyclable cheaper materials.
Co-reporter:Zanru Guo, Yujun Feng, Yu Wang, Jiyu Wang, Yufeng Wu and Yongmin Zhang
Chemical Communications 2011 - vol. 47(Issue 33) pp:NaN9350-9350
Publication Date(Web):2011/07/18
DOI:10.1039/C1CC12388B
An amidine-based polymer was prepared by combination of RAFT polymerization and “click” reaction, and the polymer undergoes a hydrophobic−hydrophilic transition upon the stimulus of CO2.
Co-reporter:Yongmin Zhang, Yujun Feng, Jiyu Wang, Shuai He, Zanru Guo, Zonglin Chu and Cécile A. Dreiss
Chemical Communications 2013 - vol. 49(Issue 43) pp:NaN4904-4904
Publication Date(Web):2013/04/08
DOI:10.1039/C3CC41059E
A wormlike micellar system that undergoes a fully reversible, repeatable “sol–gel” transition upon alternative treatment with CO2 and N2 has been developed based on a C18-tailed polyamine surfactant.
![N-[3-(dimethylamino)propyl]docos-13-enamide](http://img.cochemist.com/ccimg/150000/149968-48-9.png)
![N-[3-(dimethylamino)propyl]docos-13-enamide](http://img.cochemist.com/ccimg/150000/149968-48-9_b.png)
