摘要:

AbstractThe present article describes a group of new materials by the combination between organic polymer and silica gel, one of typical inorganic substances. Characteristics of these materials exist in the dimension of blending of the two components, i.e., blending at the molecular level dispersion. The new materials are transparent glassy ones, which are well expressed by a word of “Hybrid”. The hybrids are readily prepared by the sol‐gel reaction of Si(OEt)4, the precursor of silica gel, in the presence of an organic polymer which consists of a repeating unit containing ‐N(R)‐C(=O)‐ group (R=hydrogen or alkyl), i.e.,N‐alkyl orN,N‐dialkyl substituted carboxyl amide, urea and urethane groups. Hydrogen‐bond between the above group of organic polymer component and silanol group which is a key intermediate of the sol‐gel reaction plays an important role to form a homogeneous transparent material. The formation of hydrogen bond has been established by FT‐IR spectrum, i.e., the shift of vC=O absorption. Calcination of the transparent hybrid produces another interesting material of highly porous silica gel. At a higher temperature, e.g. 600°C, the organic polymer is decomposed but the framework of silica gel remains unchanged. Thus, the space which organic polymer occupies becomes a pore. The new porous silica gel is characterized by a high surface area of inner surface (∼ 810 m2/g) and a pore size

ISSN:0258-0322    

DOI:10.1002/masy.19920640103

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPerfluoro(vinyl ether) derivatives are extremely versatile monomers in preparing a variety of functional fluoropolymers. In this paper, two challenging topics in the development of novel fluoropolymers will be introduced. Carboxylated perfluoro(vinyl ether) can be copolymerized with tetrafluoroethylene to afford perfluorinated ion‐exchange membranes, which realize the innovative process for pollution‐free and energy‐saving chlor‐alkali production. Another topic includes the discovery of selective cyclo‐polymerization of specially designed difunctional perfluoromonomers such as perfluoro(allyl vinyl ether) which is readily derived from the carboxylated perfluoro(vinyl ether). The novel perfluoropolymer with a cyclic structure in the main chain is characterized by an exceptional transparency, and has been commercialized with expectation of major applications in electronics i

ISSN:0258-0322    

DOI:10.1002/masy.19920640104

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe game of molecular engineering of LC systems via combination of molecular architecture and functionalization of mesogens has opened interesting perspectives in the field of liquid crystals. This contribution summarizes different examples of this interplay using discotic liquid crystals as its basis.

ISSN:0258-0322    

DOI:10.1002/masy.19920640105

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThermotropic poly(2,2′‐oxydiethylene fumarate)‐block‐poly(2‐methyl‐1,4‐phenylene fumarate)Cis synthesized by interfacial polycondensation of α,ω‐dichlorocarbonyl‐poly(2,2′‐oxydiethylene fumarate) and fumaroyl chloride with 2‐methyl‐1,4‐dihydroxybenzene. A study of each block is carried out on the corresponding homopolymers as models of flexibleAand rigidBblocks. CopolymerCand models are characterized by1H and13C NMR, I.R. spectroscopy, SEC, DSC, TGA, X‐Ray diffractometry and electron microscopy. A phase segregation is observed inCwhenBcontent is above 50%. CopolymerCexhibits a nematic m

ISSN:0258-0322    

DOI:10.1002/masy.19920640106

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe continuous miniaturization in microelectronics requires advanced materials and processes. Novel specifically functionalized anhydride‐containing filmforming polymers which spontaneously react with bisaminoalkylsiloxanes were synthesized for use in photolithographic processes. This allows the modelling of photoresist patterns and thus enhancement of practical resolution. In addition, efficient polymeric dielectrics with improved solubility in environmentally safe solvents were developed. The latter can be patterned using the above mentioned photolithographic proces

ISSN:0258-0322    

DOI:10.1002/masy.19920640107

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractPolymers derived from 2‐[2‐(perfluoroalkyl)ethyl]‐2‐oxazolines have been prepared in very good yields with molecular weights up to 50000. The polymers are crystalline with melting temperatures (Tm's) varying from 180 to 232°C depending on the length and type of the perfluorinated side chain, have good thermal stability and are soluble in fluorinated solvents. They are effective as modifiers of surfaces of hydrophilic polymers, such as nylon‐6,6, and give acceptable complement activation parameters. Factor C3a (μg/ml) released is 5.3 in contrast to positive control value of 45.2 (activated sepharose) and negative control = 4.8. A 1:1 mixture of 2‐octyl‐2‐oxazoline and 2‐[2‐(perfluorohexyl)ethyl]‐2‐oxazoline copolymerize to give a block copolymer that exhibits two separate Tm's. The partially perfluorinated polymers also form stable monolaye

ISSN:0258-0322    

DOI:10.1002/masy.19920640108

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractDevelopment of an efficient and convenient means for preparation of aromatic cyclic oligomeric carbonates has made these materials available for a wide range of polymerization and processing studies. Building on the workbased on bisphenol A cyclics, recent efforts have concentrated on the preparation of new cyclics which afford polymers with properties substantially different from bisphenol A polycarbonate. Cyclic systems have been developed which lead to polycarbonates with improved solvent resistance, either through cross‐linking or via crystallization. Polycarbonates with both high or low glass transition temperatures have also been achieve

ISSN:0258-0322    

DOI:10.1002/masy.19920640109

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractSemi‐crystalline and amorphous aromatic polymers have become well established as high‐performance engineering polymers and composite matrices. Such polymers with functional groups introduced, may be used to toughen, and modify the processing properties of, a range of thermosetting resins, in addition to being copolymerisable, crosslinkable and/or chain‐extendable.This paper describes structure/property relationships which have been established for functionalised polyaromatics and systems which utilise

ISSN:0258-0322    

DOI:10.1002/masy.19920640110

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractWell defined all‐acrylic graft copolymers have been synthesized using the macromonomer technique. Poly(methyl methacrylate) (PMMA) macromonomers of controlled molecular weight and narrow molecular weight distribution have been synthesized by group transfer polymerization (GTP) using a protected hydroxyl functional initiator. These macromonomers were quantitatively functionalized with a polymerizable acrylic and group and copolymerized under free radical conditions with 2‐ethylhexyl acrylate (2EHA) to form the desired well defined graft copolymers in high yields. The macromonomers and the copolymers have been characterized by a variety of spectroscopic, chromatographic and thermal analysis methods. Transparent, multiphase materials with glass transition temperature (Tg) values of approximately ‐65 °C and 115 °C were obtained. The reaction conditions necessary to generate these materials most effectively have also been investigated and are described

ISSN:0258-0322    

DOI:10.1002/masy.19920640111

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe highly living character of a number of cationic polymerizations has been used to synthesize new, well defined, segmented copolymers. This has been achieved by sequential monomer additions, by grafting reactions, by macromonomer copolymerizations as well as by transfer to polymer. In the present report, a number of examples of such polymers will be presented. The new materials are based on tetrahydrofurane (THF), alkyloxazolines (ROx), cyclic amines, cyclic acetals and cyclic sulfides.

ISSN:0258-0322    

DOI:10.1002/masy.19920640112

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY