Intrinsic viscosity variation in different solvents for dendrimers and their hybrid copolymers with linear polymers
Intrinsic viscosity variation in different solvents for dendrimers and their hybrid copolymers with linear polymers
复制标题
DOI：
10.1021/ma0021343
复制
发表时间：
2001-07-03
期刊：
影响因子：
5.5
通讯作者：
Hawker, CJ
中科院分区：
文献类型：
--
作者：
Jeong, M;Mackay, ME;Hawker, CJ
窄分子量分布的聚苯乙烯标准品，聚（苄基）醚树枝状聚合物，和它们的混合嵌段共聚物的特性粘度在各种溶剂中进行了测量。所有这些聚合物的特性粘度的相对变化几乎是相等的，表明聚（苄基醚）树枝状大分子膨胀和收缩很容易与溶剂的变化。发现所有聚合物的特性粘度最大值发生在基本相同的溶剂溶解度参数下，表明与所选范围的溶剂的热力学相互作用也是等效的。混合共聚物的特性粘度在一个良好的溶剂中的两个组件被发现远远低于纯聚苯乙烯在中间分子量的特性粘度。低于和高于该质量范围，特性粘度与聚苯乙烯非常相似。然而，从中等分子量到高分子量行为的转变是相当急剧的，如通过在60-70 kDa处的快速特性粘度上升所看到的。一个较差的溶剂的树枝状聚合物，一个树枝状聚合物的特性粘度被发现独立的代数，产生相同的特性粘度的混合共聚物和原始聚苯乙烯。这种独特的行为是由于线性聚苯乙烯嵌段和高度支化的树枝状嵌段之间的新型相互作用，这是溶剂环境的函数。
The intrinsic viscosity of narrow molecular mass distribution polystyrene standards, poly(benzyl) ether dendrimers, and their hybrid block copolymers was measured in a variety of solvents. The relative change in the intrinsic viscosity fur all these polymers was almost equivalent, indicating that poly(benzyl ether) dendrimers expand and contract quite readily with a change in solvent. The intrinsic viscosity maximum for all polymers was found to occur at essentially the same solvent solubility parameter demonstrating that the thermodynamic interaction with the selected range of solvents was also equivalent. The intrinsic viscosity for hybrid copolymers in a good solvent for both components was found to fall well below the intrinsic viscosity for neat polystyrene at intermediate molecular masses. Below and above this mass range the intrinsic viscosity was quite similar to polystyrene. Yet, the transition for intermediate to high molecular mass behavior was quite sharp as seen through a rapid intrinsic viscosity rise at 60-70 kDa. A poorer solvent for the dendrimer, one where the dendrimer intrinsic viscosity was found independent of generation number, produced the same intrinsic viscosity for the hybrid copolymer and virgin polystyrene. This unique behavior is due to novel interactions between the linear polystyrene block and the highly branched dendritic block which is a function of the solvent environment.