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Conformational statistics of polymer chain terminally attached to wall (Ⅲ)——NRW model loop chain 总被引:1,自引:0,他引:1
When the two end groups of a linear polymer chain are absorbed on a solid surface,the polymer chain forms the "loop" conformation.Investigation has been made on the conformational statistics of a model loop chain by the normal landom walk (NRW) on a lattice confined in the half-infinite space.Based on the conformational distribution function of the NRW model tail chain,it is easy to deduce an analytical formula expressing the conforma-tional number of the model loop chain.It was found that the ratio of the conformational number of the model loop chain to that of the free chain varies with the power function N-2/3 when the chain length N→∞ The same result was obtained by means of the recursion equation.The ratio of the mean square end-to-end distance h2 for the model loop chain to its mean square bond length I2 is 2N/3 Compared with the free chain with the same length N,the mean square end-to-end distance of the model loop chain contracts to a certain extent.The basic relationships deduced were support 相似文献
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保尔·弗洛里(Paul J. Flory)1910年生于美国伊利诺斯州斯特林,祖辈务农,父母为教员。他1931年毕业于印第安纳州曼彻斯特大学化学系,随后进入俄亥俄州立大学,在约翰斯通(Johnston)教授指导下于1934年完成了光化学和光谱学方面的物理化学博士论文。同年,受聘于杜邦公司,开始了他在高分子科学领域的漫长研究生涯,显示出他巧妙地将化学问题加以精确数学处理的惊人才智。从那时算起近半个世 相似文献
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本文从理论上研究了聚对羟基苯甲酸酯(简称PHB或PHBA)的分子量分布。理论分析表明,由对羟基苯甲酸酯缩聚制得的PHB的分子量分布与Flory分布稍有不同,可以认为是修正的Flory分布;而由对羟基苯甲酸制得的PHBA仍可用Flory分布表征。由于未发现上述聚合物的溶剂,故不可能对其分子量分布进行实验研究。 相似文献
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Perfluorooctanoyl modified poly(vinyl alcohol)s (FPVA) were prepared by means of substituting a small amountof hydroxyl groups on the backbone of poly(vinyl alcohol), for which the initial degree of polymerization is equal to 1750.The substitution extent, defined by the number of substituting units in a chain, for the four FPVA samples was in the range of0.5-5 perfluorooctanoyl groups per chain. The FPVA samples with the highest substitution extent still had good solubility inwater. It was shown by experimental measurement at 30.0±0.1℃ that the surface tension of the aqueous solution of thehighest substituted FPVA decreased to 16.6 mN/In at a higher concentration, e.g about 0.1 g/mL. Obviously,macromolecules of FPVA exhibit a very strong tendency to adsorb at the air-water interface, because the hydrophobicperfluorooctanoyl groups in FPVA have a very high surface activity as they are in small molecular fluorinated surfactants.The chain conformation of such a model polymer adsorbed on the air-water interface was also discussed. 相似文献
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以NH4Cl-NH3·H2O为缓冲液,十六烷基三甲基溴化铵(CTAB)为荧光增强剂,用荧光分光光度计分别采集槲皮素、槲皮素-Sn(Ⅱ)配合物溶液、槲皮素-Sn(Ⅱ)-NH4Cl-NH3·H2O、槲皮素-Sn(Ⅱ)-NH4Cl-NH3·H2O-CTAB溶液以及将其溶液分别静置7h和21h后的荧光光谱,并对光谱进行分析.在不加CTAB的条件下,用紫外分光光度计分别测量加入缓冲液前后的紫外光谱.用漫反射方法测定配合物的红外光谱,并对其结构进行初步分析.在缓冲液的作用下,槲皮素-Sn(Ⅱ)配合物的结构发生了变化;通过分析,发现与缓冲液发生反应的主要基团为酚羟基,红外光谱中酚羟基的消失和NH 4基团的出现,说明了配合物中的酚羟基与NH 4发生了取代反应. 相似文献
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聚合物降解的 Monte Carlo 研究 总被引:1,自引:0,他引:1
<正> 聚合物(化学纤维、塑料和橡胶等)降解的研究对于聚合物加工和老化具有重要的实用意义.钱型聚合物的分子由 x 个链节以 x-1个化学键串联结合而成,x 称为链长或聚合度,它的分子量就是 mx,m 为一个链节的分子量.化学结合键的断裂就是降解,每发生一次断裂,一个链长为 x 的分子就分解为两个较小的分子.降解过程数学分析的任务就是研究聚合物分子量随降解程度的变化.由于聚合物通常包含着各种不同链长的分子,所论及的链长和分子量一般是指某种平均值.链长 x 的分子数占聚合物分子总数的 相似文献