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Zhai S.,CAS Shanghai Institute of Organic Chemistry | Wang B.,Key Laboratory of Molecular Engineering of Polymers Ministry of Education | Feng C.,CAS Shanghai Institute of Organic Chemistry | Li Y.,CAS Shanghai Institute of Organic Chemistry | And 4 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2010

A series of well-defined double hydrophilic graft copolymers containing poly[poly(ethylene glycol) methyl ether acrylate] (PPEGMEA) backbone and poly[poly(ethylene glycol) ethyl ether methacrylate] (PPEGEEMA) side chains were synthesized by the combination of single electron transfer-living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). The backbone was first prepared by SETLRP of poly(ethylene glycol) methyl ether acrylate macromonomer using CuBr/tris(2-(dimethylamino)ethyl)amine as catalytic system. The obtained comb copolymer was treated with lithium diisopropylamide and 2-bromoisobutyryl bromide to give PPEGMEA-Br macroinltiator. Finally, PPEGMEA-g-PPEGEEMA graft copolymers were synthesized by ATRP of poly(ethylene glycol) ethyl ether methacrylate macromonomer using PPEGMEA-Br macroinitiator via the grafting-from route. The molecular weights of both the backbone and the side chains were controllable and the molecular weight distributions kept narrow [M w/M n ≤ 1.20). This kind of double hydrophilic copolymer was found to be stimuli-responsive to both temperature and ion (0.3 M Cl - and SO 4 2-). © 2009 Wiley Periodicals, Inc.


Yang D.,Key Laboratory of Molecular Engineering of Polymers Ministry of Education | Tong L.,CAS Shanghai Institute of Organic Chemistry | Li Y.,CAS Shanghai Institute of Organic Chemistry | Hu J.,Key Laboratory of Molecular Engineering of Polymers Ministry of Education | And 2 more authors.
Polymer | Year: 2010

A series of well-defined binary hydrophilic-fluorophilic diblock copolymers were synthesized by successive atom transfer radical polymerization (ATRP) of methoxylmethyl acrylate (MOMA) and 4-(4′-p-tolyloxyperfluorocyclobutoxy)benzyl methacrylate (TPFCBBMA) followed by the acidic selective hydrolysis of the hydrophobic poly(methoxymethyl acrylate) (PMOMA) segment into the hydrophilic poly(acrylic acid) (PAA) segment. ATRP of MOMA was initiated by 2-MBP at 50 °C in bulk to give two different PMOMA homopolymers with narrow molecular weight distributions (Mw/Mn ≤ 1.15). PMOMA-b-PTPFCBBMA well-defined diblock copolymers were synthesized by ATRP of TPFCBBMA at 90 °C in anisole using Br-end-functionalized PMOMA homopolymer as macroinitiator and CuBr/PMDETA as catalytic system. The final PAA-b-PTPFCBBMA amphiphilic diblock copolymers were obtained via the selective hydrolysis of PMOMA block in dilute HCl without affecting PTPFCBBMA block. The critical micelle concentrations (cmc) of PAA-b-PTPFCBBMA amphiphilic copolymers in aqueous media were determined by fluorescence spectroscopy using pyrene as probe and these diblock copolymers showed different micellar morphologies with the changing of the composition. © 2010 Elsevier Ltd. All rights reserved.


Yang D.,Key Laboratory of Molecular Engineering of Polymers Ministry of Education | Zhang J.Z.,University of California at Santa Cruz | Fu S.,Key Laboratory of Molecular Engineering of Polymers Ministry of Education | Xue Y.,Key Laboratory of Molecular Engineering of Polymers Ministry of Education | Hu J.,Key Laboratory of Molecular Engineering of Polymers Ministry of Education
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2010

Evolving gel formation processes of colloidal hydrogels derived from high solid-content polymethacrylate microemulsions have been studied using rheological and dynamic light scattering (DLS) techniques. The critical gel points, evaluated through oscillatory shear measurement and characterized by a single power-law exponent of G′ and G″ on the frequency (the power-law exponent, n = 0.36-0.65) were influenced more by the volume fraction of polymers than by the gelling temperature. Further topological fractal analysis and rheological studies suggested that reaction-limited cluster aggregation (RLCA) may dominate the aggregation behavior of polymer nanoparticles with the fractal dimension (df) = 1.8-2.2. The DLS results showed a fast relaxation mode with a single exponential decay followed by a slow one with a stretched exponential decay, which indicated that the gradual incorporation of polymer nanoparticles or clusters into the gel network leads to the maturity of the homogenous hydrogel network. Comparative studies on a series of polymethacrylate hydrogel systems with different hydrophilicities demonstrated that a slight hydrophilicity favors gel formation. The gelation mechanism was discussed based on the in-situ aggregation of nanoparticles as well as in terms of the colloidal instability of high solid-content nanolatex. © 2009 Elsevier B.V. All rights reserved.

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