摘要:

Polystyrene derivatives with lactose, glucose, maltose, maltotriose, maltopentaose, and maltoheptaose on each benzene ring were prepared by the radical polymerization of a new class of macromers synthesized by coupling the corresponding oligosaccharide lactones withp-vinylbenzylamine. These polymers consisting of amphiphilic structural units were water-soluble, and organic solutes were bound to hydrophobic microenvironments of the polymers in water. α-D-Glucopyranose-carrying polymers were recognized and precipitated by concanavalin A. Cultivation of liver cells (hepatocytes) was attempted using culture dishes whose surface was coated with lactose-, glucose-, maltose-, and maltotriose-carrying polystyrenes. It has been found that a lactose-carrying polystyrene (PVLA) is a useful surface material for hepatocyte culture. 1) Highly specific adhesion of hepatocytes was attained for PVLA-coated dishes with or without serum supplement. 2) The cell adhesion was a threshold phenomenon with respect to the PVLA concentration on the dish. 3) The cell adhesion was effectively inhibited when hepatocytes were treated with PVLA molecules in the medium prior to culture. 4) The adhesion was not inhibited by albumin, an adhesion-inhibitory protein in serum. These findings suggest that pendent galactose residues of a PLVA molecule functioned as a strong recognition determinant for hepatocytes. We assume that multi-antennary, high-density galactose residues of PVLA are attributed to the specific adhesion of hepatocytes.

ISSN:0022-233X    

DOI:10.1080/00222338808053391

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Platinum clusters protected by polymerized micelles were prepared by radical polymerization of unsaturated surfactants which were involved in micelle-protected platinum clusters. The micelle-protected platinum clusters were successfully prepared by photoreduction of hexachloroplatinic acid in water in the presence of unsaturated surfactants. The platinum clusters thus obtained were characterized by electron microscopy and IR and1H-NMR spectroscopies. The average diameter of the platinum particles was about 1 nm by electron microscopy, and the polymerization was confirmed by IR and1H-NMR spectra. The platinum clusters thus obtained proved to be highly active catalysts for visible light-induced hydrogen generation in the system of EDTA/Ru(bpy)32+/MV2+. The polymerized micelle-protected platinum clusters showed higher catalytic activity than the linear polymer-protected one. The catalytic activity was affected by the electric charge of the surfactants in the polymerized micelle-protected platinum clusters. Nonionic polymers were superior to those having anionic and cationic hydrophilic groups from the viewpoint of catalytic activity. The nonionic polymerized micelle forms rigid hydrophobic cores which help charge separation and the formation of a sequential potential field.

ISSN:0022-233X    

DOI:10.1080/00222338808053392

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Polymeric solid electrolytes which show bi-or single-ionic tunneling were prepared, and their unique ion conduction was applied for the design of some devices. Poly [(oligooxyethylene) methacrylatel] /MX hybrids and poly [(oligooxyethylene) methacrylate-co-methacrylic acid alkali metal salts] were prepared as typical models of those tunneling systems. These showed ionic conductivities above 10−5and 10−7S/cm at room temperature, respectively. An all-solid-state electrochromic display and a dry battery were prepared with these polymeric solid electrolytes. The all-solid-state electrochromic display showed excellent coloring and bleaching response by 1–3 V. The all-solid-state battery showedVoc= 3.1 V stability for over 2 weeks. Their characteristics as well as their mechanism are also reported.

ISSN:0022-233X    

DOI:10.1080/00222338808053393

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Macroinitiators with primary amino substituents were synthesized by one of the following techniques: a) cyanoethylation of cellulose followed by diborane reduction to produce aminopropylcellulose,1;b) nitration, then SnCl2reduction of poly(arylene ether sulfone), 5, to produce poly(2-aminoarylene ether sulfone),2;c) phthalimidation of 5 followed by hydrazinolysis to yield poly(2-aminomethylarylene ether sulfone),3; and d) LiAlH4reduction of poly(cyanophenylene arylene ether) to poly(aminomethylphenylene arylene ether),4. Heterogeneous grafting of Λ-benzyl-L-glutamate-N-carboxyanhydride, 8, to Polymer1resulted in a nonrandom distribution of amino acid residues; α-helical conformations were detected at low BLG-NCA/NH2ratios (<5 amino acids). Using molar ratios ranging from 1 to 100 of 8, relative to the amine concentration, grafting to Polymers3and4was effected in anhydrous THF at room temperature under homogeneous conditions. If reaction times between 24 and 48 h are utilized, high grafting efficiencies (>80%) are obtained. The conformation of the polypeptide chain was evaluated by NMR and infrared spectroscopy. Polypeptides grafted to Polymers 3 and 4 appeared to adopt the expected conformation for the chain length predicted, i.e., a progression from random coil (<8 amino acids) to β-pleated sheet (8–13 amino acids) to α-helix (> 13 amino acids). The benzyl ester functions on the BLG grafts are subject to direct modification with amine nucleophiles; studies with butylamine correlate reaction conditions with extent of ester vs peptide cleavage. In the presence of 1-hydroxybenzotriazole, aminolysis of the ester is favored and conversions to Λ-amides up to 75% without peptide cleavage are achieved.

ISSN:0022-233X    

DOI:10.1080/00222338808053394

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Studies of the synthesis of organic polymers potentially possessing electrically conductive, piezoelectric, and nonlinear optical properties are described. The electrically conducting polymer studies center on polyaromatic quinondiimines, analogs of the known conducting polymer polyaniline. Various polycondensation polymers based on anthraquinone and on heterocyclic quinones were examined. Multiazoarylene polymers were also synthesized by oxidative coupling of aromatic diamines. Their fidms were found to ben-dopable but were not very conductive. Polyesters and polyformals containing multiazoarylene units also were not highly conductive. Liquid crystal properties were observed for multiazobisphenol sebacate polyesters. Toward piezoactive polymers, a polyvinylidene fluoride macromonomer was synthesized via telomerization of vinylidene fluoride with methanol. Films of poly(bicyclobutane-1-carbonitrile) were found to show piezoactivity. 2-Ethyl-2-butylmalonimide was synthesized and subjected to ring-opening polymerization with the aim of synthesizing novel piezoactive β-pleated sheet polymalonimides. As to NLO polymers, AB polyesters (up to 20-fold increases) could be attained by incorporating the nonlinear optical chromophores into a polar main-chain polymer. This effect is the manifestation of overall increases in the field-induced molecular alignment through cooperative effects of the separate molecular dipoles. While investigations on thin films of the same copolymers showed that the poled molecular orientation could be frozen and maintained in the absence of the field, the degree of orientation in thin films was found to be much less than that in the solution, but considerably more than an uncorrelated assembly.

ISSN:0022-233X    

DOI:10.1080/00222338808053395

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The intramolecular photodimerization of thymine bases present on the side chain of a variety of synthetic oligomers and polymers was studied in detail in various organic solvents, and particularly in the case of thymine-containing polylysines, over a wide range of pH. Effects of solvents, presence of the complementary base, and spacers on the photoreaction were examined, and the conformational changes of the polymers were discussed in relation to their functionalities. Intermolecular photodimerization was further studied, and its applicability to photoresists was shown.

ISSN:0022-233X    

DOI:10.1080/00222338808053396

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

By virtue of its ability to generate hydrated electrons (eaq−) and various radicals as reductants, the pulse radiolysis technique has been employed for investigating the mechanism of action of peroxidase, cytochrome P-450, and cytochrome oxidase. The oxy forms of hemoproteins, such as myoglobin, peroxidase, and cytochrome P-450, were reduced by hydrated electrons to form the higher oxidation states of these hemoproteins. From these results, the reactive oxygen intermediate of cytochrome chrome P-450 is discussed. The reduction of cytochrome oxidase by the 1-methylnicotinamide radical was investigated. A decrease of the 830-nm band was detected due to the reduction of “visible” copper. After the first phase of the reduction of copper, the return of the 830-nm band corresponding to oxidation of copper was observed. Concomitantly, the absorption at 605 and 445 nm due to the reduction of heme α increased. This suggests that 1-methylnicotinamide radical reacts with the “visible” copper and subsequently flows to heme α by intramolecular migration.

ISSN:0022-233X    

DOI:10.1080/00222338808053397

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Although cyclic ketene acetals, such as 2-methylene-1, 3-dioxepane, undergo quantitative free-radical ring-opening polymerization, their reactivity in copolymerization is rather low. In order to find a series of monomers that have high reactivities in copolymerization and still undergo free radical ring-opening polymerization, a series of cyclic acrylates was synthesized and polymerized. For example, β-bromolactic acid condensed with benzaldehyde to give a cyclic acetal lactone which on treatment with base gave the cyclic acrylate. Free-radical solution polymerization at 140°C of the cyclic acrylate, which produced a benzyl radical upon ring opening, gave quantitative ring opening. However, in bulk at 120°C, only 20% of the rings were opened during poiymerization. The resulting polymers containing the pyruvate ester units were shown to be highly biodegradable with microorganisms. Vesicles containing these cyclic acrylates on the end of one of the hydrophobic chains of the lipidlike molecules were shown to undergo free-radical ring-opening polymerization to give polymerized vesicles which were biodegradable. In order to discover groups other than carbonyl groups and strained rings that would promote free-radical ring-opening polymerization, a series of spiromethylenecyclohexadienes were prepared and polymerized. Thus, 3-methylenespiro [5,5] undeca-1,4-diene in bulk at 130°C gave a polymer in which 79% of the rings had opened and in solution at 130°C gave a polymer in which nearly all of the rings had opened. A benzo derivative, 3-methylene-8,9-benzo [5,5] undeca-1,4,8-triene, gave a polymer that is essentially an alternating copolymer ofp-xylylene ando-xylylene and has a very high thermal decomposition temperature. A tricyclic dispirocyclohexadiene derivative was shown to undergo double free-radical ring-opening polymerization to give a polymer with expansion in volume containing ap-phenylene group in the backbone.

ISSN:0022-233X    

DOI:10.1080/00222338808053398

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The structure and properties of various reaction products resulting from the polymerization of carbon disulfide and carbon diselenide are reviewed. In many respect, CSe2behaves like CS2. However, CS2can be polymerized (without a catalyst and in the absence of irradiation) only under high pressure, and this reaction yields a semiconductor. On the other hand, CSe2is easily polymerized under ambient conditions. Depending upon the polymerization conditions, products are obtained which range from insulators to metals and superconductors. Results indicate that (CSe2) reacts to form a head-to-head linear polymer, which thermally decomposes at relatively low temperatures to produce free selenium. This free selenium is the likely origin of the observed superconductivity.

ISSN:0022-233X    

DOI:10.1080/00222338808053399

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The synthesis and semiconcentrated and dilute solution properties of two series of ampholytic acrylamide ionomers, poly(acrylamide MPTMA/AMPS) and poly(acrylamide METMA/MES), are reported as a function of the ionic content and added salt concentration. The viscosity dependence on shear rate was measured with a cone/plate Brookfield viscometer for sermiconcentrated solution and with a Cannon-Ubbelohde four-bulb shear dilution capillary viscometer for dilute solution at 25 ± 0.1°C. The two series of ampholytic acrylamide ionomers showed a characteristic pseudoplastic shear-thinning behavior under both conditions. The semiconcentrated solution viscosity parametersmandnin the power-law model, η =mγn-1, were determined and found to be functions of the ionic content. The viscosity at selected shear rates was found to be a complex function of the salt concentration. The intrinsic viscosity [η] was determined and compared with molecular parameters determined by light scattering under identical conditions. The dilute-solution properties of the ampholytic ionomers were found to resemble the properties of neutral polyacrylamide previously reported in the literature.

ISSN:0022-233X    

DOI:10.1080/00222338808053400

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor