树枝形高分子特性黏数反常行为的理论研究

THEORETICAL STUDY OF ANOMALOUS INTRINSIC VISCOSITY FOR DENDRIMERS

首先借助自洽场理论计算了树枝形高分子的径向密度分布函数,然后在二区域模型理论基础上,系统研究了树枝形高分子的"代数"、活性中心官能度、重复单元链节长度、有效相关系数和排除体积参数等对其特性黏数的影响.在理解树枝形高分子特性黏数与其微结构关系的基础上,从流体力学相互作用的角度,揭示了树枝形高分子的特性黏数不能反映其聚合度大小,而反映其平均携带溶剂能力的物理根源,从而为树枝形高分子功能的优化设计提供理论指导.

In order to physically elucidates the anomalous intrinsic viscosity of dendrimers,first,the radial segmental density profile of dendrimers is calculated by the self-consistent mean field method.Secondly,based on the two-zone model proposed,the intrinsic viscosity as a function of generation of dendrimers with the following parameters,including the number of generations,the functionality of the core,the length of spacer,the effective coefficient of correlation and the excluded volume is systematically investigated.Thirdly,the origin of dendrimers＇anomalous intrinsic viscosity is elucidated in the microscopic scale,namely the competition of the number fraction between the two kinds of monomers without the capability of dragging solvent,which is caused by the increase of volume of the core and the back-folding ability caused by entropy effect.Finally,it is physically elucidated that the nature of the intrinsic viscosity is the reflection of the ability per monomer of dendrimer to averagely drag solvent molecules alone rather than the reflection of the degree of polymerization.This research will be benefit for the optimum design of dendrimer materials in the corresponding application areas.