非对称半结晶两嵌段共聚物的微相分离与结晶行为的模拟退火研究

Simulated Annealing Study of Microphase Separation and Crystallization in Asymmetric Semicrystalline Diblock Copolymers

利用模拟退火方法研究非对称半结晶两嵌段共聚物熔体分别在弱分离和强分离条件下的结晶过程.考察微相分离作用和结晶作用的相对强度对柱状组成的两嵌段共聚物平衡形态的影响.研究结果表明,当嵌段间的相互排斥作用较弱时,结晶便破坏了柱状畴;当此相互作用足够强时,结晶过程可以有效地被限制在熔体微相分离所形成的柱状畴内.另外,介于上述两种情形之间还存在一个模板区域,此时熔体形成的柱状畴大部分被保留下来,但在局部会变形或连通.这些结果和文献报道的实验结果一致.当嵌段间的相互排斥作用非常强时,结晶被抑制,微相分离主导最终形态,观察到了非晶态结构.

A simulated annealing method is used to study the mierophase separation and crystallization in cylinder-forming semierystalline diblock copolymers. The final structure depends on the relative strength of the microphase separation and the crystallization of one block copolymers. As the interblock segregation strength is relatively weak, crystallization disrupts cylindrical microphase. As the interblock segregation strength is sufficiently strong, crystallization is effectively confined within cylindrical domains formed by microphase separation in the melt. A range of intermediate segregation strength exists between the two cases, in which the crystallization is templated but not wholly confined within the nanoscale domains prescribed by microphase separation. The melt morphology is mostly retained in cooling, and the local distortions and connections between cylinders occur due to crystallization. The simulation is consistent with recently reported experimental results. In addition, as the interblock segregation strength is very strong, the crystallization is restrained which results in amorphous structures.