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991.
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993.
Yoshinori Katsuyama Takayuki Kurokawa Tatsuo Kaneko Jian Ping Gong Yoshihito Osada Norishige Yotsukura Taizo Motomura 《Macromolecular bioscience》2002,2(4):163-169
The inhibition of germination and development of zoospores originating from Laminaria angustata originated on various kinds of hydrogels is studied. The effects of the water content of the gel (the degree of swelling), the electrical nature (neutral, positive charge, negative charge), the charge density, the counterions of hydrogels on the inhibition of zoospore germination and development of gametophytes are phenomenologically investigated. Among the gels investigated, poly(acrylic acid) (PAA) gel showed a dramatic inhibition to germination, and might serve as a novel, environmentally safe inhibitor of zoospore adhesion. 相似文献
994.
995.
Candan Erbil Seval Aras Nurseli Uyanik 《Journal of polymer science. Part A, Polymer chemistry》1999,37(12):1847-1855
This work was done to investigate the effect of three different ionizable components (acrylic acid, AA; itaconic acid, IA; maleic acid, MA) on the volume phase transitions and swelling equilibria of thermoshrinking type N-isopropylacrylamide (NIPAAM) gels in water. NIPAAM copolymer gels were synthesized by free radical crosslinking copolymerization of NIPAAM with each of AA, IA, and MA, the difference being both between configurations and carboxyl group numbers, and pK values, in the presence of N,N′-methylene-bis-acrylamide (MBAAM). The influence of comonomer concentrations (1, 5, and 10 mol %), MBAAM content (0.0096, 0.0193, and 0.0288 g), and comonomer type (AA, IA, and MA) on the external views, the percentages of equilibrium mass, and volume swellings [S %(m), S % (v)], the number-average molecular weight between crosslinks (M̄c), effective crosslinking densities (νe), the change of the collapse temperatures, and swelling ratios in the swelling–shrinking process of the gels were examined. It was observed that phase transition temperature and swelling degree in the case of MA having a cis configuration and higher pK value are larger than those of the samples containing IA and AA. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1847–1855, 1999 相似文献
996.
John R. Ebdon Ian Soutar Paul Brown Anthony R. Lane Alasdair J. McCabe Linda Swanson 《Journal of Polymer Science.Polymer Physics》1999,37(16):2127-2136
The phosphorescence characteristics of naphthyl labelled poly(acrylic acid) film samples have been studied as a function of temperature, with a view to investigating the effect of matrix control on the level of triplet emission observed. Two relaxations, which serve to deactivate the excited triplet states have been detected from phosphorescence lifetime measurements: the α (or glass) and the βtransition (which can be associated with the onset of rotation of the carboxylic acid group). Investigation of the emission from 2‐benzoyl naphthalene dispersed within both an acrylic acid‐methyl methacrylate copolymer and a PAA film, respectively, has revealed that the more intense, longer‐lived phosphorescence results from the modified polymer. This is considered to reflect the existence of (i) hydrogen‐bonding interactions induced by the presence of carboxylic acid groups which serve to form a rigid matrix and (ii) intramolecular aggregates of methyl methacrylate units which create hydrophobic‐rich pockets, capable of sustaining intense phosphorescence at room temperature. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2127–2136, 1999 相似文献
997.
Anders Sdergrd 《Journal of polymer science. Part A, Polymer chemistry》1998,36(11):1805-1812
Acrylic acid was grafted onto poly(ε-caprolactone) (PCL) films by using electron beam (EB) preirradiation technique. The effect of reaction time, monomer concentration, radiation dose, time between irradiation and grafting, radiation atmosphere, and polymer crystallinity on the extent of grafting were studied. Silver and tin ions were attached to the grafted chains in order to study the grafting process. The irradiation in air was initially more rapid, but the final extent of grafting was the same when irradiated in nitrogen atmosphere. Maximum grafting extents exceeding 400% could be obtained. The optimal grafting was obtained at an acrylic acid to water ratio of 30 : 70. The grafting process could be initiated at a dose as low as 12 kGy. The grafting process proved to start at the surface and was extended into the bulk with time. The ability to form crystals was reduced as the grafting extent increased. The water uptake of the poly(ε-caprolactone)-graft-poly(acrylic acid) was increasing with increasing grafting extent, but reached a maximum of ca 100% for all grafting extents above 85%. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1805–1812, 1998 相似文献
998.
Yukitoshi Takeshita Toshihiro Ichino Shiro Nishi 《Journal of polymer science. Part A, Polymer chemistry》1998,36(14):2493-2501
The physical properties and the structure of a poly(styrene-co-butadiene) rubber (SBR) and poly(acrylonitrile-co-butadiene) rubber (NBR) latex mixture film are studied in relation to the composition of SBR/NBR for optimization as the precursor of a polymer electrolyte. The composition of SBR50/NBR50 is most suitable in terms of mechanical strength and ionic conductivity. The relationship between the mechanical strength and the structure is analyzed using a simple equivalent mechanical model modified from the Takayanagi model. Our model gives better agreement with experimental results and extends the range of validity of the model to the cocontinuous phase type morphologies. It is possible to estimate the mechanical strength from the continuity of the mechanical supporting phase, calculated from the mechanical model. The tensile properties are found to be strongly affected by the fragile component. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2493–2501, 1998 相似文献
999.
A new strategy was developed for producing a polymer latex with trimodal particle size distribution by adding a second seed of polymer particles and some additional surfactants during polymerization. The polymerization was investigated by following the variation of the particle size, the size distribution, the number of particles, the surface tension and surfactant surface coverage at different stages of the polymerization process. The results showed that both the size and the size distribution can be easily controlled by varying the amount of additional surfactants and the second seed of polymer particles. The secondary nucleation was achieved when the surface coverage of particles was over 70%, and the amount of small particles formed increased with increasing amount of additional surfactants. The introduction of the additional surfactants had no significant effect on the size and number of middle particles, but reduced the size of large particles and caused the number of large particles to remain more stable because of the suppression of limited flocculation. Copyright © 1998 John Wiley & Sons, Ltd. 相似文献
1000.
A. Mühlebach B. Müller C. Pharisa M. Hofmann B. Seiferling D. Guerry 《Journal of polymer science. Part A, Polymer chemistry》1997,35(16):3603-3611
Poly(vinyl alcohol) (PVA) was partially modified by polymer analogous reaction with acrylic and methacrylic acid and with 2-vinyl-4,4-dimethyl-azlactone to obtain water-soluble polymers with pendant (meth)acrylate and acrylamide groups. Aqueous solutions of these polymers were crosslinked by UV-irradiation within seconds to form transparent networks with potential for use in contact lenses. The water content of these hydrogels was studied as a function of polymer molecular weight, the acetate, (meth)acrylate, and methacrylamide contents and irradiation conditions. The hydrogels showed good mechanical properties, even at low crosslinker (<5 mol %) and high water contents (60–80%). The formation kinetics and stability of aggregates, investigated by combined GPC/light-scattering measurements of samples annealed and/or stored at different temperatures (−20 to 100°C), give insight into PVA secondary structures. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3603–3611, 1997 相似文献