Lian Cheng, Wang Le, Chen Xueqian, Han Xia, Zhao Shuangliang, Liu Honglai, Hu Ying
State Key Laboratory of Chemical and Engineering and Department of Chemistry, East China University of Science and Technology , Shanghai 200237, China.
Langmuir. 2014 Apr 15;30(14):4040-8. doi: 10.1021/la5003429. Epub 2014 Apr 4.
A key problem in designing thermoresponsive polymer brushes on a solid surface is to find a relation between the targeted thermoresponsive properties and controllable conditions. Usually, a temperature-thickness curve showing the heating-induced swelling behavior of polymer brushes is chosen as the relation by either experimental or theoretical investigation. In this work, a lattice density functional theory (LDFT) developed previously is employed to investigate the temperature-thickness curves for five different types of polymer brushes, where the density profiles of polymer brushes calculated by LDFT are compared directly with simulation. It is found that the thermoresponsive behavior of a polymer brush can be characterized by the bulk phase behaviors of its corresponding polymer solution, including UCST, LCST, both UCST and LCST, closed LOOP and hourglass-shaped, which implies that the bulk phase diagram of polymer solutions can help us to find an appropriate polymer brush for a targeted thermoresponsive behavior. As an example, we show that the swelling behavior of a thermoresponsive polymer brush found in the experiment could be predicted by our LDFT results with the bulk phase diagram of real polymer solution only.
在固体表面设计热响应性聚合物刷的一个关键问题是找到目标热响应特性与可控条件之间的关系。通常，通过实验或理论研究，选择一条显示聚合物刷加热诱导溶胀行为的温度-厚度曲线作为这种关系。在这项工作中，我们采用先前开发的晶格密度泛函理论（LDFT）来研究五种不同类型聚合物刷的温度-厚度曲线，其中通过LDFT计算得到的聚合物刷密度分布直接与模拟结果进行比较。研究发现，聚合物刷的热响应行为可以由其相应聚合物溶液的本体相行为来表征，包括上临界溶液温度（UCST）、下临界溶液温度（LCST）、同时具有UCST和LCST、闭环形和沙漏形，这意味着聚合物溶液的本体相图可以帮助我们找到具有目标热响应行为的合适聚合物刷。例如，我们表明，仅通过真实聚合物溶液的本体相图，我们的LDFT结果就能预测实验中发现的热响应性聚合物刷的溶胀行为。
