Elucidation of Static and Dynamic Properties of Highly Branched Polymers

以苯酚和多聚甲醛为催化剂，在乙酸中缩合制备了高支化聚合物。以邻甲酚和多聚甲醛为原料，以HC1为催化剂，在乙酸中缩合制备了线型聚合物。测定了高支化聚合物和线性聚合物的特性粘度[η]和均方旋转半径<S^2>对分子量的依赖关系，并阐明了侧链对溶液中分子构象的影响。对于含有月桂基的线性聚合物，正辛烷中酚类主链聚集在分子中心，烷基侧链在分子外部。构象就像胶束。另一方面，MIBK中酚侧链和烷基侧链共存，构象扩展。对于高支化聚合物，侧链对构象的影响不显著。这是由于线状聚合物的柔韧性。采用阴离子偶联法制备了一种接枝共聚物，其主干为2-乙烯吡啶，支数为68个。分支点之间的主干跨度大约是线性聚苯乙烯的劳斯段尺寸的两倍。动态双折射和动态粘弹性测量表明，该共聚物的复合杨氏模量和应变光学系数与线性聚苯乙烯相似。橡胶和玻璃组分的应力光学系数分别与线性聚苯乙烯的应力光学系数一致，这意味着在研究的整个频率范围内没有检测到微相分离的迹象。在玻璃组分的频率依赖性中未观察到分支效应。在橡胶区，短时间观察到的模态归因于聚苯乙烯分支的运动，长时间观察到的另一模态与聚2-乙烯吡啶树干的运动有关。虽然聚（2-乙烯基吡啶）的分子量远高于线状聚苯乙烯缠结链的分子量，但由于支链对缠结的抑制作用，并未明显观察到橡胶平台区。少

Highly branched polymer was prepared by the condensation of phenol with paraformaldehyde in acetic acid using HC1 as catalyst. Linear polymer was prepared by the condensation of o-cresol with paraformaldehyde in acetic acid using HC1 as catalyst. The molecular weight dependence of intrinsic viscosity [η] and mean-square radius of gyration <S^2> for the highly branched and linear polymers were determined and the effect of side chain on the molecular conformation in solution was elucidated, respectively. For the linear polymer with lauroyl group, the phenolic main chain was aggregated in the center of molecule and the alkyl side chain was external to the molecule in n-octane. The conformation was like a micelle. On the other hand, the phenolic main and alkyl side chain coexisted and the conformation was extended in MIBK. For the highly branched polymer the effect of side chain on the conformation is not remarkable. This is due to the flexibility of linear polymer.A graft copolymer having … More poly(2-vinylpyridine) trunk and sixty-eight polystyrene branches was prepared by anionic coupling method. The trunk span between branching points was about two times wider than the Rouse segment size for linear polystyrene. Dynamic birefringence and dynamic viscoelastic measurements around Tg zone showed that the complex Young's modulus and the strain optical coefficient of the copolymer was similar to those of linear polystyrene. The stress optical coefficients for the rubbery and the glassy components, respectively, agreed with those for linear polystyrene, meaning that no indication of microphase separation was ideologically detected over a whole rang of frequencies studied. The effect of branching was not observed in the frequency dependence of the glassy component. In the rubbery zone, the mode observed at short times was attributed to motion of polystyrene branches, and the other mode at long times was related to the motion of poly(2-vinylpyridine) trunk. Although Mw of poly(2-vinylpyridine) was much higher than the molecular weight of entanglement strands of linear polystyrene, the rubbery plateau zone was not clearly observed, possibly due to inhibition ofentanglements by branching. Less