Sixun Zheng

Shanghai Jiao Tong University, Shanghai, Shanghai Shi, China

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Publications (156)517.44 Total impact

  • Houluo Cong, Jingang Li, Lei Li, Sixun Zheng
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    ABSTRACT: Poly(ethylene oxide)-block-poly(sodium p-styrenesulfonate) (PEO-b-PSSNa) diblock copolymer was synthesized and then incorporated into epoxy to obtain the nanostructured epoxy thermosets containing polyelectrolyte nanophases. This PEO-b-PSSNa diblock copolymer was synthesized via the radical polymerization of p-styrenesulfonate mediated with 4-cyano-4-(thiobenzoylthio)valeric ester-terminated poly(ethylene oxide). The formation of polyelectrolyte (i.e., PSSNa) nanophases in epoxy followed a self-assembly mechanism. The precursors of epoxy acted as the selective solvent of the diblock copolymer, and thus, the self-assembled nanostructures were formed. The self-organized nanophases were fixed through the subsequent curing reaction. By means of transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS), the morphologies of the nanostructured epoxy thermosets containing PSSNa nanophases were investigated. In the glassy state, the epoxy matrixes were significantly reinforced by the spherical PSSNa nanodomains, as evidenced by dynamic mechanical analysis. The measurement of dielectric properties showed that, with the incorporation of PSSNa nanophases, the dielectric constants of the epoxy thermoset were significantly increased. Compared to the control epoxy, the dielectric loss of the nanostructured thermosets still remained at quite a low level, although the values of dielectric loss were slightly increased with inclusion of PSSNa nanophases.
    The Journal of Physical Chemistry B 12/2014; 118(50). DOI:10.1021/jp5089355 · 3.38 Impact Factor
  • Houluo Cong, Jingang Li, Lei Li, Sixun Zheng
    European Polymer Journal 12/2014; 61:23–32. DOI:10.1016/j.eurpolymj.2014.09.018 · 3.24 Impact Factor
  • Houluo Cong, Sixun Zheng
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    ABSTRACT: In this contribution, we reported the synthesis of poly(N-isopropylacrylamide)-block-poly(acrylic acid) (PNIPAAm-b-PAA) copolymer networks via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. The PNIPAAm-b-PAA block copolymer networks were characterized by means of Fourier transform infrared spectroscopy (FTIR) and small angle X-ray scattering (SAXS). The volume phase transition (VPT) temperatures of the PNIPAAm-b-PAA hydrogels were measured by means of micro-differential scanning calorimetry (micro-DSC). It was found that the block copolymer hydrogels displayed the VPT temperatures lower than the control PNIPAAm hydrogel. Compared to the control PNIPAAm hydrogel, the deswelling and reswelling properties of the block copolymer hydrogels were significantly improved. The improved thermoresponsive properties of the PNIPAAm-b-PAA hydrogels have been interpreted on the basis of the formation of the architecture of the block copolymer networks.
    Colloid and Polymer Science 10/2014; 292(10):2633-2645. DOI:10.1007/s00396-014-3314-9 · 2.41 Impact Factor
  • Kun Wei, Lei Wang, Lei Li, Sixun Zheng
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    ABSTRACT: Bead-like PNIPAAm copolymers with double-decker silsesquioxane (DDSQ) in the main chains were synthesized via a reversible addition–fragmentation chain transfer (RAFT) polymerization approach. The macromolecular chain transfer agent used for the RAFT polymerization was synthesized via the polycondensation of 3,13-dihydroxyproplyl DDSQ with S,S′-bis(α,α′-dimethyl-α′′-propargyl acetate)trithiocarbonate. The organic–inorganic copolymers with variable contents of DDSQ were characterized by means of 1H nuclear magnetic resonance spectroscopy and gel permeation chromatography. Transmission electron microscopy showed that the bead-like PNIPAAm copolymers were microphase-separated in bulk. It was found that the glass transition temperatures (Tg's) of PNIPAAm microdomains of the organic–inorganic copolymers were lower than plain PNIPAAm and decreased with increasing the content of DDSQ. The bead-like PNIPAAm copolymers displayed the self-assembly behavior in aqueous solutions. Depending on the content of DDSQ, the bead-like organic–inorganic copolymers can self-assemble into spherical or vesicular nanoobjects in aqueous solutions. Both micro-differential scanning calorimetry (Micro-DSC) and cloud point analysis with UV-vis spectroscopy showed that the lower critical solution temperature (LCST) behavior of PNIPAAm subchains in the bead-like copolymers was significantly affected by the POSS cages in the main chains.
    09/2014; 6(2). DOI:10.1039/C4PY00786G
  • Yulin Yi, Lei Li, Sixun Zheng
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    ABSTRACT: Poly(epsilon-caprolactone)-block-poly(N-vinyl pyrrolidone) diblock copolymers grafted from macrocyclic oligomeric silsesquioxane (MOSS) (denoted MOSS[PCL-b-PVPy](12)) were synthesized via the sequential polymerizations involving ring-opening polymerization (ROP) of epsilon-caprolactone (CL) and RAFT/MADIX polymerization of N-vinyl pyrrolidone (NVP). The organic-inorganic brush-like diblock copolymers were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). Small angle X-ray scattering (SAXS) showed that all the MOSS[PCL-b-PVPy](12) was microphase-separated in the amorphous state. The microphase-separated morphologies were quite dependent on the length of PVPy blocks and the crystallization behavior of PCL subchains was significantly affected by the lengths of PVPy subchains. In aqueous solutions, the MOSS[PCL-b-PVPy](12) can be self-assembled into the polymeric micelles as evidenced by dynamic light scattering (DLS) and transmission election microscopy (TEM). The critical micelle concentrations of the brush-like diblock copolymers increased with increasing the lengths of PVPy blocks. It is proposed that the stability of the micellar cores was increased with the macrocyclic molecular brush structure of the diblock copolymers and the formation of the MOSS aggregates via MOSS MOSS interactions.
    Polymer 08/2014; 55(16). DOI:10.1016/j.polymer.2014.06.083 · 3.77 Impact Factor
  • Jingang Li, Houluo Cong, Lei Li, Sixun Zheng
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    ABSTRACT: The block copolymer networks composed of poly(N-isopropylacrylamide) (PNIPAM) and poly(sodium p-styrenesulfonate) were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization with α,ω-didithiobenzoate-terminated poly(sodium p-styrenesulfonate) (PSSNa) as the macromolecular chain transfer agent. It was found that the block copolymer networks were microphase-separated as evidenced by means of transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). In the block copolymer networks, spherical or cylindrical PSSNa microdomains were finely dispersed into continuous PNIPAM matrixes. In comparison with unmodified PNIPAM hydrogel, the nanostructured hydrogels displayed improved thermoresponsive properties. In addition, the swelling ratios of the PSSNa-modified PNIPAM hydrogels were significantly higher than that of plain PNIPAM hydrogel. The improvement of thermoresponse was attributable to the formation of the PSSNa nanophases, which promoted the transportation of water molecules in the cross-linked networks.
    ACS Applied Materials & Interfaces 07/2014; 6(16). DOI:10.1021/am503148v · 5.90 Impact Factor
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    ABSTRACT: In this contribution, we reported a facile synthesis of poly(methyl methacrylate)-block-poly(N-vinyl pyrrolidone) (PMMA-b-PVPy) diblock copolymers via sequential radical polymerizations mediated by isopropylxanthic disulfide (DIP). It was found that the radical polymerization of N-vinyl pyrrolidone (NVP) mediated by DIP was in a controlled and living manner. In contrast, the polymerization of methyl methacrylate mediated by DIP displayed the behavior of telomerization, affording xanthate-terminated PMMA with a good control of molecular weights while the conversion of monomer was not very high. The xanthate-terminated PMMA can be successfully used as the macromolecular chain transfer agent for the polymerization of NVP via RAFT/MADIX process and thus PMMA-b-PVPy diblock copolymers can be successfully synthesized via sequential radical polymerization mediated by isopropylxanthic disulfide. One of these diblock copolymers was incorporated into polybenzoxazine and the nanostructured thermosets were obtained as evidenced by transmission electron microscopy, small angle X-ray scattering, and dynamic mechanical thermal analysis. The formation of nanostructures in polybenzoxazine thermosets was ascribed to a reaction-induced microphase separation mechanism. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014
    Journal of Polymer Science Part A Polymer Chemistry 04/2014; 52(7). DOI:10.1002/pola.27075 · 3.54 Impact Factor
  • Houluo Cong, Lei Li, Sixun Zheng
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    ABSTRACT: In this work, we investigated the effect of formation mechanisms of nanophases on the morphologies and thermomechanical properties of the nanostructured thermosets containing block copolymers. Toward this end, the nanostructured thermosets involving epoxy and block copolymers were prepared via self-assembly and reaction-induced microphase separation approaches, respectively. Two structurally similar triblock copolymers, poly(e-caprolactone)-block-poly(butadiene-co-styrene)-block-poly(e-caprolactone) (PCL-b-PBS-b-PCL) and poly(epsilon-caprolactone)-block-poly(ethylene-co-ethylethylene-co-styrene)block-poly(e-caprolactone) (PCL-b-PEEES-b-PCL) were synthesized via the ring-opening polymerization of e-caprolactone (CL) with am-dihydroxyl-terminated poly(butadiene-co-styrene) (HO-PBS-OH) and a.,w-dihydroxyl-terminated poly(ethylene-co-ethylethylene-co-styrene) (i.e., HO-PEEES-OH) as the macromolecular initiators, respectively; the latter was obtained via the hydrogenation reduction of the former. Both the triblock copolymers had the same architecture, the identical composition and close molecular weights. In spite of the structural resemblance of both the triblock copolymers, the formation mechanisms of the nanophases in the thermosets were quite different. It was found that the formation of nanophases in the thermosets containing PCL-b-PBS-b-PCL followed a reaction-induced microphase separation mechanism whereas that in the thermosets containing PCL-b-PEEES-b-PCL was in a selfassembly manner. The different formation mechanisms of nanophases resulted in the quite different morphologies, glass transition temperatures (Tg's) and fracture toughness of the nanostructured thermosets. 2014 Elsevier Ltd. All rights reserved.
    Polymer 03/2014; 55(5). DOI:10.1016/j.polymer.2014.01.049 · 3.77 Impact Factor
  • Chongyin Zhang, Yulin Yi, Lei Li, Sixun Zheng
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    ABSTRACT: In this work, we investigated the nanostructures and mechanical properties of epoxy thermosets containing a macromolecular miktobrush composed of poly(ε-caprolactone) (PCL) and polydimethylsiloxane (PDMS) side chains. The novel macromolecular miktobrush was synthesized via the combination of reversible addition–fragmentation chain transfer and ring-opening polymerizations. In the brush-like copolymer the molar ratio of PCL to PDMS was controlled to be 1:1 and the length of PCL chains was controlled to be close to that of PDMS chains (i.e., L PDMS = 1000). The densely grafted miktobrush copolymer was incorporated into epoxy and the nanostructured thermosets were obtained as evidenced by means of transmission electron microscopy and dynamic mechanical thermal analysis. The results of small-angle X-ray scattering showed that the formation of nanostructures in the thermosets followed a self-assembly mechanism. The measurement of critical stress intensity factor (K 1C) showed that the nanostructured thermosets displayed the improved fracture toughness owing to the formation of nanostructures.
    Journal of Materials Science 01/2014; 49(3). DOI:10.1007/s10853-013-7809-4 · 2.31 Impact Factor
  • Yulin Yi, Sixun Zheng
    RSC Advances 01/2014; 4(54):28439. DOI:10.1039/c4ra02624a · 3.71 Impact Factor
  • Kun Wei, Lei Li, Sixun Zheng, Ge Wang, Qi Liang
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    ABSTRACT: In this contribution, we report the synthesis of organic-inorganic random polymers from methacrylate-terminated poly(ethylene oxide) (MAPEO) (Mn = 950) and 3-methacryloxypropylheptaphenyl polyhedral oligomeric silsesquioxane (MAPOSS) macromers via reversible addition-fragmentation chain transfer (RAFT) polymerization with 4-cyano-4-(thiobenzoylthio) valeric acid (CTBTVA) as the chain transfer agent. The organic-inorganic random copolymers were characterized by means of (1)H NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The results of GPC indicate that the polymerizations were carried out in a controlled fashion. Transmission electron microscopy (TEM) showed that the organic-inorganic random copolymers in bulk were microphase-separated and the POSS microdomains were formed via POSS-POSS interactions. In aqueous solutions the organic-inorganic random copolymers were capable of self-assembling into spherical nanoobjects as evidenced by transmission electron microscopy (TEM) and dynamic laser scattering (DLS). The self-assembly behavior of the organic-inorganic random copolymers was also found to occur in the mixtures with the precursors of epoxy. The nanostructures were further fixed via subsequent curing reaction and thus the organic-inorganic nanocomposites were obtained. The formation of nanophases in epoxy thermosets was confirmed by transmission electron microscopy (TEM) and dynamic mechanical thermal analysis (DMTA). The organic-inorganic nanocomposites displayed the enhanced surface hydrophobicity as evidenced by surface contact angle measurements.
    Soft Matter 12/2013; 10(2):383-94. DOI:10.1039/c3sm51531a · 4.15 Impact Factor
  • Kun Wei, Lei Wang, Sixun Zheng
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    ABSTRACT: A series of novel organic–inorganic copolymers with polyhedral oligomeric silsesquioxane (POSS) in the main chains were synthesized via the copper-catalyzed Huisgen 1,3-dipolar cycloaddition polymerization approach. Toward this end, we synthesized 3,13-azidopropyloctaphenyl double-decked silsesquioxane (DDSQ). This difunctional POSS macromer was used to copolymerize with α,ω-dialkynyl-terminated oligoethylenes with variable number of ethylene units. The organic–inorganic copolymers were obtained with the mass fraction of POSS up to 79%. Gel permeation chromatography showed that the high-molecular-weight copolymers were successfully obtained in all the cases. Differential scanning calorimetry showed that the amplitude of glass transitions for these copolymers was very feeble, suggesting that the segmental motions responsible for the glass transitions was highly restricted with DDSQ cages in the main chains. Thermogravimetric analysis showed that the organic–inorganic hybrid copolymers displayed extremely high thermal stability. Contact angle measurements showed that these organic–inorganic copolymers are highly hydrophobic and possessed very low surface energy. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4221–4232
    Journal of Polymer Science Part A Polymer Chemistry 10/2013; 51(19):4221-4232. DOI:10.1002/pola.26836 · 3.54 Impact Factor
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    ABSTRACT: In this work, we investigated the effect of topological structures of block copolymers on the formation of nanophase in epoxy thermosets containing amphiphilic block copolymers. Two block copolymers composed of poly(ε-caprolactone) (PCL) and poly(2,2,2-trifluroethyl acrylate) (PTFEA) blocks were synthesized to possess linear and star-shaped topologies. The star-shaped block copolymer comprised a polyhedral oligomeric silsesquioxane (POSS) core and eight poly(ε-caprolactone)-block-poly(2,2,2-trifluroethyl acrylate) (PCL-b-PTFEA) diblock copolymer arms. Both the block copolymers were synthesized via the combination of ring-opening polymerization and reversible addition-fragmentation chain transfer / macromolecular design via the interchange of xanthate (RAFT/MADIX) process; they were controlled to have the identical composition of copolymerization and lengths of blocks. Upon incorporating both the block copolymers into epoxy thermosets, the spherical PTFEA nanophases were formed in all the cases. However, the sizes of PTFEA nanophases from the star-like block copolymer were significantly lower than those from the linear diblock copolymer. The difference in the nanostructures gave rise to the different glass transition behavior of the nanostructured thermosets. The dependence of PTFEA nanophases on the topologies of block copolymers is interpreted in terms of the conformation of the miscible subchain (viz. PCL) at the surface of PTFEA microdomains and the restriction of POSS cages on the demixing of the thermoset-philic block (viz. PCL).
    The Journal of Physical Chemistry B 06/2013; 117(27). DOI:10.1021/jp402084u · 3.38 Impact Factor
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    ABSTRACT: In this article, we report the preparation of crosslinked epoxy microspheres with diameters of 5–10 μm prepared via phase-inverted phase separation induced by polymerization in the thermosetting blend of epoxy and poly(ε-caprolactone). The surfaces of the epoxy microspheres were functionalized to bear 2-bromopropionyl groups, which were further used as initiators to obtain poly(glycidyl methacrylate) (PGMA) grafted epoxy microspheres via the surface-initiated atom transfer radical polymerization approach. The PGMA-grafted epoxy microspheres were then employed to react with 3-aminopropyltrimethoxylsilane (APTMS) to obtain the functionalized epoxy microspheres, the surface of which contained a great number of trimethoxysilane groups. A co-sol–gel process between the APTMS-functionalized epoxy microspheres and tetraethoxysilane was performed, and organic–inorganic glassy solids were obtained. The organic–inorganic glasses were used as precursors for accessing macroporous silica materials via pyrolysis at elevated temperatures. The hierarchical porosity of the resulting macroporous silica was investigated by means of field emission scanning electronic microscopy, transmission electronic microscopy, and surface-area Brunauer–Emmett–Teller (BET) measurements. We found that the macroporous silica possessed BET surface areas in the range 183.9–235.2 m2/g, depending on the compositions of their precursors. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
    Journal of Applied Polymer Science 06/2013; 128(5). DOI:10.1002/app.38339 · 1.64 Impact Factor
  • Lei Wang, Jingang Li, Lei Li, Sixun Zheng
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    ABSTRACT: Organic–inorganic hybrid diblock copolymers composed of poly(ε-caprolactone) and poly(MA POSS) [PCL-b-P(MA POSS)] were synthesized via reversible addition-fragmentation chain transfer polymerization of 3-methacryloxypropylheptaphenyl polyhedral oligomeric silsesquioxane (MA POSS) with dithiobenzoate-terminated poly(ε-caprolactone) as the macromolecular chain transfer agent. The dithiobenzoate-terminated poly(ε-caprolactone) (PCL-CTA) was synthesized via the atom transfer radical reaction of 2-bromopropionyl-terminated PCL with bis(thiobenzoyl)disulfide in the presence of the complex of copper (I) bromide with N,N,N′,N″,N″-pentamethyldiethylenetriamine. The results of molecular weights and polydispersity indicate that the polymerizations were in a controlled fashion. The organic–inorganic diblock copolymer was incorporated into epoxy to afford the organic–inorganic nanocomposites. The nanostructures of the organic–inorganic composites were investigated by means of transmission electron microscopy and dynamic mechanical thermal analysis. Thermogravimetric analysis shows that the organic–inorganic nanocomposites displayed the increased yields of degradation residues compared to the control epoxy. In the organic–inorganic nanocomposites, the inorganic block [viz., P(MA POSS)] had a tendency to enrich at the surface of the materials and the dewettability of surface for the organic–inorganic nanocomposites were improved in terms of the measurement of surface contact angles. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
    Journal of Polymer Science Part A Polymer Chemistry 05/2013; 51(9):2079-2090. DOI:10.1002/pola.26597 · 3.54 Impact Factor
  • Chongyin Zhang, Lei Li, Sixun Zheng
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    ABSTRACT: In this contribution, we reported the investigation of the formation and confined crystallization behavior of polyethylene nanophases in epoxy thermosets. The nanostructured epoxy thermosets were prepared by the use of a poly(ε-caprolactone)-block-polyethylene-block-poly(ε-caprolactone) (PCL-b-PE-b-PCL) triblock copolymer. The crystalline midblock (viz. PE) of the triblock copolymer was prepared from an α,ω-diacetoxy-terminated polycyclooctadiene with the molecular weight as high as Mn = 11,000, which was synthesized via the ring-opening metathesis polymerization (ROMP) of cyclooctadiene catalyzed by Grubbs second generation catalyst. The formation of PE nanophases in epoxy thermosets was evidenced with transmission electronic microscopy (TEM), small-angle X-ray scattering (SAXS) and dynamic mechanical thermal analysis (DMTA). It was found that in the nanostructured thermosets, the spherical nanophases of PE with the size of 20–30 nm in diameter were dispersed into the continuous epoxy matrices. Wide angle X-ray diffraction (XRD) showed that the formation of PE nanophases did not alter the structure of PE crystals. The investigations of isothermal and nonisothermal crystallization kinetics showed that the crystallization of PE in the nanostructured thermosets was in a confined manner and the confinement has been interpreted on the basis of nanoscaled space, interdomain connectivity, and the cross-linked structures of epoxy matrices.
    Macromolecules 04/2013; 46(7):2740-2753. DOI:10.1021/ma4000682 · 5.93 Impact Factor
  • Houluo Cong, Lei Li, Sixun Zheng
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    ABSTRACT: In this work, we reported the synthesis of poly(N-isopropyl acrylamide)-block- poly(N-vinylpyrrolidone)-block-poly(N-isopropylacrylamide) triblock copolymer (PNIPAAm-b-PVPy-b-PNIPAAm) via reversible addition-fragmentation chain transfer polymerization/macromolecular design via the interchange of xanthate (RAFT/MADIX) process. This approach was further employed to prepare the PNIPAAm-b-PVPy block copolymer networks with N,N′-methylenebisacrylamide as the crosslinker. The results of small angle X-ray scattering (SAXS) indicate that the PNIPAAm-b-PVPy block copolymer networks were microphase-separated, in which PVPy was dispersed into PNIPAAm matrix as the microdomains. The architecture of block copolymer networks allows investigating the effect of the blocked permanently hydrophobic chains (viz. PVPy) on the deswelling and reswelling behavior of the PNIPAAm hydrogels. It was found that the diffusion of water molecules in PNIPAAm-b-PVPy block copolymer networks was in a non-Fickian and accelerating manner. The swelling ratios of the PNIPAAm-b-PVPy hydrogels were significantly higher than that of control PNIPAAm hydrogel. Compared to control PNIPAAm hydrogel, the PNIPAAm-b-PVPy hydrogels displayed an accelerated response to the external temperature changes in terms of deswelling and reswelling tests. The accelerated thermoresponsive properties is ascribed to the presence of the PVPy blocks in the PNIPAAm-b-PVPy block copolymer networks, which could act as the hydrophilic tunnels to facilitate the diffusion of water molecules in the PNIPAAm networks.
    Polymer 02/2013; 54(4):1370–1380. DOI:10.1016/j.polymer.2012.12.069 · 3.77 Impact Factor
  • Kun Wei, Lei Wang, Sixun Zheng
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    ABSTRACT: In this contribution, we reported the synthesis of organic–inorganic polyurethanes with polyhedral oligomeric silsesquioxane (POSS) in the main chains. Toward this end, 3,13-dihydroxypropyloctaphenyl double-decker silsesquioxane (DDSQ) was synthesized; this POSS diol was used as a chain extender to obtain hybrid polyurethanes with DDSQ in the main chains. By controlling the molar ratio of 3,13-dihydroxypropyloctaphenyl DDSQ to 1,4-butanediol (BDO), organic–inorganic polyurethanes were obtained with a content of DDSQ up to 48 wt%. The results of 1H nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC) showed that 3,13-dihydroxypropyloctaphenyl, DDSQ, can be successfully used as a chain extender to afford linear organic–inorganic polyurethanes. Differential scanning calorimetry (DSC) showed that the organic–inorganic polyurethanes displayed enhanced glass transition temperatures (Tg's) compared to control polyurethane; the Tg's increased with increasing content of DDSQ in the main chains. Compared to control polyurethane, the organic–inorganic polyurethanes displayed improved thermal stability in terms of thermogravimetric analysis (TGA). With the inclusion of DDSQ in the main chains, the organic–inorganic polyurethanes displayed enhanced surface hydrophobicity.
    02/2013; 4(5):1491-1501. DOI:10.1039/C2PY20930F
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    ABSTRACT: In this contribution, we reported the preparation of mesoporous silica with a reactive block copolymer as the porogen via sol-gel process. Firstly, poly(glycidyl methacrylate)-block-poly(-caprolactone)-block-poly(glycidyl methacrylate) triblock copolymer (PGMA-b-PCL-b-PGMA) was synthesized with the combination of ring-opening polymerization (ROP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. Thereafter, the triblock copolymer was functionalized via its reaction with 3-aminopropyltriethoxysilane (APTES) to afford a new reactive block copolymer bearing triethoxysilane moieties. The latter was employed to perform the inter-component sol-gel reactions with tetraethoxysilane (TEOS) to obtain the organic-inorganic composites with various compositions. The organic-inorganic composites were subsequently used as the precursors to obtain the mesoporous silica materials via pyrolysis at elevated temperatures. The surface-area Brunauer-Emmett-Teller (BET) measurements indicate that the materials of mesoporous silica with adjustable porosity have been successfully obtained.
    Journal of Macromolecular Science Part A 01/2013; 50(4). DOI:10.1080/10601325.2013.768152 · 0.74 Impact Factor
  • Rentong Yu, Sixun Zheng, Xiuhong Li, Jie Wang
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    ABSTRACT: We report an investigation of the influence of block copolymer architectures on formation of nanophases in epoxy thermosets via reaction-induced microphase separation approach. Toward this end, three binary block copolymers composed of polystyrene (PS) and poly(ε-caprolactone) (PCL) were synthesized via the combination of ring-opening polymerization (ROP) and atomic transfer radical polymerization (ATRP). These block copolymers possess PS-b-PCL diblock, PS-b-PCL-b-PS triblock, and PCL-b-PS-b-PCL triblock architectures; they were carefully controlled to have the identical composition and overall molecular weights. It was found that the block copolymers with different architectures in epoxy thermosets displayed quite different reaction-induced microphase separation behavior as evidenced with the results of atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and dynamic mechanical thermal analysis (DMTA). The morphological transition from spherical to cylindrical to lamellar nanophases occurred with increasing the content of the block copolymer in the thermosets containing PS-b-PCL diblock copolymer. In the thermosets containing PS-b-PCL-b-PS triblock copolymer, unilamellar and multilamellar nanophases were formed depending on the content of the triblock copolymer. In contrast, the macroscopic phase separation occurred in the thermosets containing PCL-b-PS-b-PCL triblock copolymer. The behavior of nanophases in these thermosetting blends have been accounted for the demixing behavior of the miscible blocks (viz. PCL) during the reaction-induced microphase separation and the influence of copolymer architectures on the morphologies of PS microdomains.
    Macromolecules 11/2012; 45(22):9155-9168. DOI:10.1021/ma3017212 · 5.93 Impact Factor

Publication Stats

3k Citations
517.44 Total Impact Points

Institutions

  • 2003–2014
    • Shanghai Jiao Tong University
      • • Department of Polymer Science and Engineering
      • • State Key Laboratory of Metal Matrix Composites
      Shanghai, Shanghai Shi, China
  • 2005
    • Shanghai University of Engineering Science
      Shanghai, Shanghai Shi, China
  • 1998–2003
    • The Hong Kong University of Science and Technology
      Chiu-lung, Kowloon City, Hong Kong
  • 1995–2001
    • University of Science and Technology of China
      • • Department of Polymer Science and Engineering
      • • Department of Materials Science and Engineering
      Luchow, Anhui Sheng, China