【作者】 王彪；

【导师】 张程祥；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2007， 硕士

【摘要】 本文通过自洽场理论研究了物理缔合高分子溶液的相分离并通过计算应力突变的方法确定了高分子溶液的凝胶化转变。缔合高分子是指含有“粘性单体”的高分子,这些粘性单体可以形成可逆的物理结点,进而形成可逆的凝胶。高分子系统控制相分离的重要参数是_χN,调整高分子体积分数φ_P和作用参数_χN得到高分子溶液的相图。研究发现随着高分子体积分数φ_P的增加,相分离的临界值_χN先降低后升高,整个相图不对称,相分离_χN最小值偏向体积分数小的方向。增大高分子粘性单体的间隔,相分离的_χN增加;减小高分子粘性单体的间隔,相分离的_χN降低。相分离后的高分子系统提取出浓相对其施加简单剪切,系统由平衡态变成非平衡态,两态自由能差值与形变量的比值即为应力。通过应力的突变可以确定高分子的凝胶化转变点。首先得到凝胶化转变图线,发现随着高分子体积分数的增加,凝胶化转变_χN的临界值降低。增加高分子链单体数,凝胶化转变_χN的临界值降低,也就是说高分子链单体数的增加促进凝胶的产生。以上方法得到的结果与已有的数值模拟结果符合得很好。更多还原

【Abstract】 Polymer solution phase separation and gelation transition always polymer science domain interesting topic. As a result of polymer to the temperature sensitivity, we can regulate temperature in order to separate polymer from mixing solution by the stage separation. Therefore phase separation have widely applications for polymer purified experiments and industries production. Gelation is very important in polymer material domain. It has many excellent function. Sol-gel transition always polymer science extremely active topic, especially sol-gel method in chemistry sample preparation and actual production have widespread application. So polymer solution phase separation and sol-gel transition theory research is very significant. Specially explore new method reveal research domain importantly.The paper work is carries on under the self-consistent field theory frame. We utilize grid self-consistent field method study on the physically associating polymer solution. Paper contents divide into two parts: First, we utilize self-consistent field equation research polymer solution phase separation. Second, in the foundation which separation, we introduces gel transition judge law, Namely, utilize stress change suddenly judge rich polymer gel transition.One,study phase separation .First we structure polymer single chain partition function, obtain system free energy through monomer potential field and polymer volume fraction conjugate relation, finally through iteration solution. When two state free energy change satisfy certain precision, we resume system finally evolve equilibrium state.We are through polymer mutual parameter and volume fraction relation instead. As a result of polymer mutual parameter inverse the temperature, therefore along with the polymer volume fraction increase, phase curve first reduce then elevate, under hollow. Moreover, our system solvent and the polymer mixture, is the polymerization degree asymmetrical situation, the phase diagram is not symmetric, the critical point deviation polymer volume fraction small direction. We obtain the result with theory result which has been consistent. Moreover we further studied polymer sticker monomer gap, the solvent size have differently influence for polymer solution phase separation. The findings indicated, when polymer sticker monomer gap increase, phase separates mutual parameterχN increases, the increase scope quite is big, nearly changes the same scope with monomer gap; When polymer sticker monomer gap reduces, phase separation mutual parameterχNreducing which needs, also reduces scope quite is small. When solvent size reduced, phase separation mutual parameterχNincreasing, this is because solvent size reduce, unit volume dissolution polymer monomer ability enhancement, polymer monomer and solvent compatible enhancement. We study the result which obtains to polymer scientific experiment research and actual production have certain instruction significance.Two, gel transition. Polymer solution separates two phase, one phase is rich polymer, another phase is poor polymer. We withdraw polymer rich phase, exerts to it simply shear causes it to have deformation, this time system is in the non-equilibrium state, corresponding states free energy. the difference free energy of two state and the shape variable ratio is equal to the stress. Then we increase mutual parameterχN , through the stress variation judge the rich phase polymer gel phase transition. We obtained a series of results through the compute; First obtained rich phase polymer sol-gel transition, finally indicated which along with volume fraction increase, mutual parameter reduce. Next change polymer chain monomer number, finally discovered increase monomer number causes gel marginal value to change slightly, in other words, the monomer number increase can promote gel transition.Phase separation and gel transition study through polymer, we obtained quite good result, with the theory result which has been consistent, For this method compute simple, therefore it has specially advantage in application.更多还原