无规超支化链亚浓溶液热力学性质的研究

Scaling theory is regarded as one of the most important theoretical tools to describe the thermodynamics of semidilute solutions of linear polymer chains, but whether it is a universal theory for other branched polymers has not been clearly confirmed experimentally. Randomly hyperbranched polymers, as one of the most important types of branched polymers, has been thoroughly studied to elucidate the chain architecture-solution property relation in dilute solution in the past few decades, while such a correlation study in semidilute polymer solution has lagged far behind. So far, how the branching effect influences the interchain penetration, the homogeneity, and the thermodynamic property of semidilute polymer solutions has not been well-understood and studied experimentally. In this proposed work, we propose to combine polymer synthetic chemistry and physical measurement to study the thermodynamics of semidilute solutions of randomly hyperbranched polymer: 1) a series of model hyperbranched polystyrene samples with uniform length of branched subchain will be prepared; 2) their semidilute solution properties such as osmotic pressure, osmotic compressibility, and correlation length will be carefully measured; 3) the correlation between the chain architecture parameter, solution concentration, solvent quality and solution property will be established to verify the universality of scaling theory in semidilute solution. In addition, an appropriate physical model will be proposed to reasonably explain the possible inconsistence between experimental observation and theoretical prediction. The completion of this project can help to improve the polymer theory in semidilute solution, and promote the structure-property correlation research.

标度理论是描述高分子线形链亚浓溶液热力学行为的重要理论工具，但其相关推论是否对于支化型拓扑结构高分子仍具有普适性还缺乏有力的实验证据。无规超支化高分子作为一类重要的支化型高分子，在高分子链拓扑结构与稀溶液性质的相关性研究中受到了广泛的关注，然而，其亚浓溶液相关研究却远远落后。支化效应如何影响亚浓溶液中的链间互穿、溶液网络均匀性以及溶液热力学性质还没有在实验上得到回答。本项目提出将化学合成和精准测量相结合，通过合成支化子链可控的窄分布模型超支化链样品、并测量其亚浓溶液热力学量，如渗透压、渗透压缩因子以及相关长度等，最终建立链结构参数、溶剂性质、溶液浓度与溶液热力学量之间的定量关系，从而验证标度理论对超支化高分子的普适性。此外，针对实验测量与理论预测间可能存在的差异，我们将提出合理的物理模型予以解释。本项目的顺利完成可帮助完善高分子亚浓溶液理论，并推动超支化高分子结构和性质相关性的研究。

建立高分子链拓扑结构与溶液性质间的定量关系是高分子科学中的基本问题之一。在本项目中，我们对无规超支化链的在不同浓度区间的溶液性质进行了研究。在本项目中，我们获得了以下重要研究成果：1）阐明了支化链长及其分布、支化密度和支化图案对超支化高分子溶液链尺寸、粘度等物理性质的影响规律；2）在实验上揭示了膜孔间流场相互作用及孔道预受限效应对线形及超支化高分子链过孔行为的定量影响，也从原理上解释了不同超滤研究中过孔迁移曲线转变宽度及过膜临界流速存在差异的现象，为利用超滤技术分离、表征和分级各种拓扑结构大分子链（包括线形链）奠定了坚实的基础；3）澄清先前研究中长期存在的争议问题，而且还提供了详实的实验数据用于典型支化体系（超支化及梳形）内部动力学的理论计算；4）研究了两亲超支化共聚物在溶液中的的降解过程，并建立超支化共聚物与降解性能的关系；5）揭示了在θ溶剂条件下三体相互作用对超支化链构象的支配作用的不可忽略性。本项目研究基本完成了预期的内容并达到了预期的目标，为理解超支化高分子在稀溶液和亚浓溶液中的构性关系提供了有益借鉴。在项目执行期间，共发表通讯作者研究论文16篇。