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The sol-gel transition of methylcellulose (MC) solutions in the presence of ortho-methoxycinnamic acid (OMCA) or cetyltrimethylammonium bromide (CTAB) and in the coexistence of OMCA and CTAB was determined by the rheological measurement. It has been found that the sol-gel transition temperature of MC solutions increases linearly with the concentration of either OMCA or CTAB in solution, respectively. However, in the coexistence of OMCA and CTAB, the sol-gel transition temperature of MC solutions remains invariable, independent of the concentration of CTAB in solution. The experimental results show that OMCA has priority to adsorb on the methyl group of MC chains to form polymer-bound aggregates. In particular, these aggregates inhibit the hydrophobic interaction between CTAB and the methyl group of MC chains completely. Taking into account the fact that OMCA is almost insoluble in MC-free solutions but dissolves very well in aqueous MC solutions, we propose the formation of the core-shell architecture prompted by OMCA and the methyl group of MC chains, with the methyl group of MC chains serving as the core and the self-assembly of OMCA molecules serving as the shell. Obviously, the formation of the core-shell structure increases the solubility of OMCA, improves the stability of methyl groups of MC chains at high temperatures and inhibits the hydrophobic interaction between CTAB and the methyl group of MC chains in solution. The abnormal behavior relating to the sol-gel transition of MC solutions in the presence of OMCA or in the coexistence of OMCA and CTAB is therefore explained. Upon UV irradiation, the sol-gel transition temperature of MC solutions in the presence of OMCA, or in the coexistence of OMCA and CTAB, decreases notably. However, the dependence of the sol-gel transition temperature of MC solutions as a function of OMCA concentration, or CTAB concentration in the presence of OMCA, does not change after UV irradiation. 相似文献
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介绍作者在“高分子物理实验”精品课程建设中所做的一些工作,如:坚持对实验教学进行研究、探索实验教学新模式、建设教材、构建网络教学环境等。 相似文献
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"高分子物理"(在中国科学技术大学叫"高聚物的结构与性能")和"高分子物理实验"课是该校高分子科学与工程系本科生的必修课。为了讲好和全面建设这两门课,作者倡导并积极开展教学研究,发表39篇教学研究论文,作者把这些研究心得和成果及时引入教学中,先后编写和出版了十几本教材及教学参考书,教学质量不断提高,并逐步形成了有鲜明特色的教学,在国内高校产生了很好的影响。通过多方面的建设,2005年"高聚物的结构与性能"被评为国家级精品课程,2006年"高分子物理实验"被评为安徽省精品课程。 相似文献
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