Domain-Boundary Structure of Styrene-Isoprene Block Copolymer Films Cast from Solutions. 5. Molecular-Weight Dependence of Spherical Microdomains
Domain-Boundary Structure of Styrene-Isoprene Block Copolymer Films Cast from Solutions. 5. Molecular-Weight Dependence of Spherical Microdomains
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DOI：
10.1021/ma60078a055
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发表时间：
1980-09
期刊：
影响因子：
5.5
通讯作者：
T. Hashimoto;M. Fujimura;H. Kawai
中科院分区：
文献类型：
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作者：
T. Hashimoto;M. Fujimura;H. Kawai
合成了一系列聚异戊二烯含量几乎相等（约15wt%）但总分子量不同的聚苯乙烯和聚异戊二烯的二嵌段聚合物，以研究固态球形微区体系（聚异戊二烯球分散在聚苯乙烯基体中）的微区尺寸、微区间距和微区-边界界面相厚度随分子量的变化。用小角X射线散射技术定量分析表明，球形畴的大小（半径R）和畴间距离D分别随聚异戊二烯嵌段和整个嵌段聚合物的分子量的2/3次方而变化，而界面厚度几乎与分子量无关（约1.8nm）。2/3幂定律与Helfand和Wassermann平衡理论预测的结果一致，但由于溶剂蒸发过程中遇到的非平衡效应，R和D的绝对值远低于理论值。因此，固态的球形畴系统处于亚稳态，具有归因于过量界面面积或界面体积的过量自由能，这与层状微畴系统形成对比，其中系统非常接近平衡状态。
A series of diblockpolymers of polystyrene and polyisoprene having nearly equal polyisoprene content (about 15 wt%) but differenttotal molecular weight were synthesized to study the domain size, interdomain distance, and the thickness of the domain-boundary interphase as a function of molecular weight for the spherical microdomain system in the solid state (polyisoprene spheres dispersed in a polystyrene matrix). Quantitative analyses with the small-angle X-ray scattering technique indicated that the size of the spherical domain (radius R) andinterdomain distance D vary, respectively, with the molecular weight of the polyisoprene block and that of the entire block polymer to the2/3 power, while the interfacial thickness is almost independent of the molecular weight covered in this work (about 1.8 nm). The 2/3 power law is consistent with the results predicted from the equilibrium theory of Helfand and Wassermann but the absolute values of R and D are far below the theoretical values, due to a nonequilibrium effect encountered in the solvent evaporation process. Thus the spherical domain systems in the solid state are in a metastable state with an excess free energy attributed to an excess interfacial area or interfacial volume, which contrasts with the lamellar microdomain systems, where the systems are very close to the equilibrium state.