Conducting graft copolymers of pyrrole and thiophene with random copolymers of methyl methacrylate and 3-methylthienyl methacrylate

Random copolymers of 3-methyl thienylmethacrylate and methyl methacrylate were synthesized via free radical polymerization. Electro-copolymerizations of random copolymers with thiophene and/or pyrrole were carried out in acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB), water-p-toluene sulfonic acid (PTSA) solvent-electrolyte couples. Oxidative polymerization of thiophene functionalized random copolymer was also achieved by constant current electrolysis and chemical polymerization. The characterizations were done by conductivity measurements, cyclic voltammetry (CV), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravimetry analysis (TGA), scanning electron microscopy (SEM).     

New polysaccharide-g-polyacrylonitrile copolymers: synthesis and thermal characterization

Various natural and modified polysaccharides (i.e. arabic gum, tragacanth gum, xanthan gum, sodium alginate, chitosan, sodium carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose) were modified using ceric-initiated graft polymerization of acrylonitrile under inert atmosphere. Grafting was confirmed using spectral (FT-IR) proofs. The grafting parameters were determined by conventional methods. Thermal characteristics of the homopolymer-free copolymers were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) under nitrogen atmosphere. The major thermal transitions as well as the activation energy of the major decomposition stages were investigated. The polyacrylonitrile (PAN)-grafted polysaccharides were recognized to be thermally stable more than the corresponding non-grafted substrates, although they begin to decompose at relatively lower temperatures than the non-grafted counterparts. Copyright © 2003 John Wiley & Sons, Ltd.     

Novel poly(vinyl ether) block copolymers: Synthesis and colloidal stabilization of α-Fe2O3 in water and organic solvents

 Novel poly(vinyl-methylether)-b-poly(vinyloxy-4-butyric acid) diblock copolymers were made for the purpose of colloidal stabilization of particles in liquids. The synthesis via cationic polymerization with HI/I₂ initiation and the characterization of such novel diblock copolymers is described. A set of polymers was prepared including block copolymers with different block length ratios and the two separate homopolymers having the chemical composition of one of the blocks. Colloidal stabilization of α-Fe₂O₃ particles in water could be realized with all polymers except with the (vinylmethylether) homopolymer. One of the block copolymers was used for evaluation of the stabilizing abilities in organic solvents. Stable α-Fe₂O₃ dispersions could be prepared in solvents with very different polarities, ranging from methanol to toluene. In addition, it is shown that particles stabilized with these block copolymers can be easily transferred from water to an organic liquid. Received: 15 May 1997 Accepted: 13 October 1997     

GRAFT COPOLYMERIZATION OF ACRYLAMIDE ONTO POLY(N-PARA-TOLYLACRYLAMIDE) FILMS INITIATED BY CERIC ION

Functional monomers having phenylcarbamoyl and p-tolylcarbamoyl were synthesized. Binary initiation system consisted of Ce~(4+) and these functional monomers could initiate acrylamide polymerization. It was found that acrylamide could graft copolymerize onto macromolecules having these functional monomers units. The formation of graft copolymer has been verified by its percentage of water absorption, contact angle with water, XPS and SEM photographs. The reaction mechanism was proposed and the main reactive site of graft ocpolymerization initiated by Ce~(4+) would take place predominantly at the functional pendant group.     

Molecular architecture and conformation of macromolecules of novel polysilanes

Molecular-weight parameters of new silane homo- and copolymers were analyzed. For all polymers, theM _w values are close ((6.0–8.6)·10⁴), the curves of molecular weight distribution are unimodal, andM _w/M _n=2−2.5. Cyclic fragments or those containing the −C=C− groups make the major contribution to the polysilane chain rigidity. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2430–2433, December, 1998.     

Rise of photoluminescence in the photolysis of EuIII complexes with copolymers of acrylic acid and butyl methacrylate

The luminescence and photochemical properties of Eu^III complexes with copolymers of acrylic acid and butyl methacrylate have been studied by luminescence, IR spectroscopy, and EXAFS.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 958–959, May, 1994.     

苯乙烯-p-乙烯基苯甲酸两亲性嵌段共聚物在乙醇中自组装行为的电镜观察

两亲性嵌段共聚物在只对其中一链段为良溶剂的选择性溶剂中 ,能够自组装形成胶束 .胶束的形态和尺寸大小依赖于两链段的性质 ,共聚物的组成、浓度、溶剂的性质等[1] .这一性质使得嵌段共聚物在分子识别、药物和其他物质的输送、基因疗法、水系涂料、污染物的除去、纳米复合材料的制备、催化剂以及传感器等方面展示着潜在的应用前景 .因此 ,两亲性嵌段共聚物的合成及其在选择性溶剂中的自组装行为的研究近年来颇受关注[2 ] .依据两链段的比例不同 ,嵌段共聚物可形成星状胶束和“板寸头”(Ｃｒｅｗ ｃｕｔ)型胶束[3 ] .当可溶段远比不溶段长时…     

NANOSTRUCTURES OF FUNCTIONAL BLOCK COPOLYMERS

Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, self-assembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films withnanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisoprenc-block-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50 μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass faction of 20% relative to the triblock or the totalPtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrixof PCEMA and Pl. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannelswere formed by extracting out hPtBA with solvent. Alternatively. larger channels were obtained from extracting out hPtBAand hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeabilityconstants ～6 orders of magnitude higher than that of low-density polyethylene films.     

含有机硅多嵌段共聚物的研究Ⅳ.含有机硅多嵌段共聚物的富氧功能

研究了几种新型含有机硅二元和三元多嵌段共聚物的氧、氮选择透过性能。其中双酚A聚羟基醚-聚二甲基硅氧烷二元多嵌段共聚物-(PHE-PDMS)_n的透氧系数Po_2=510Barrer、氧氮分离系数a o_2/N_2=2.2,聚苯醚-聚二甲基硅氧烷-聚对羟基苯乙烯三元多嵌段共聚物-(PPO-PDMS-pHS)_n的Po_2=156 Barrer、do_2/N_2=2.4,两者都具有良好的力学性能。此外,含有机硅三元多嵌段共聚物与聚三甲硅基丙炔(PTMSP)起薄复合后,改善了PTMSP超薄膜的透气稳定性。其JO_2≈1.0×10~(-3)cm~2/cm~2·s·cmHg,do_2/N_2≥2.0。