Shah Manas, Ganesan Venkat
Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, USA.
J Chem Phys. 2009 Feb 7;130(5):054904. doi: 10.1063/1.3072339.
Recent experimental observations have suggested an intimate connection between the chain conformations and mechanical properties of semicrystalline multiblock copolymers. Motivated by these studies, we present a theoretical study evaluating the bridging/looping fractions in a model of semicrystalline multiblock copolymers. We model the noncrystalline block (A) as a flexible Gaussian chain and the crystalline block (B) as a semiflexible chain with a temperature dependent rigidity and interactions that favor the formation of parallel oriented bonds. Using self-consistent field theory, the bridging fractions of the various domains in different multiblock copolymers (ABA, BAB, ABABA, and BABAB) are evaluated and compared with their flexible counterparts. In general, we observe that for both triblock and pentablock copolymers, rendering one of the blocks crystallizable promotes bridging in that component while reducing the bridging in the other noncrystallizable component. Moreover, the bridging fractions in tri- and pentablock copolymers were seen to be quantitatively similar except insofar as being normalized by the volume fraction of bridgeable units.
最近的实验观察表明，半结晶多嵌段共聚物的链构象与机械性能之间存在密切联系。受这些研究的启发，我们开展了一项理论研究，评估半结晶多嵌段共聚物模型中的桥接/成环分数。我们将非晶区嵌段（A）建模为柔性高斯链，将结晶区嵌段（B）建模为具有温度依赖性刚性且相互作用有利于形成平行取向键的半柔性链。使用自洽场理论，评估了不同多嵌段共聚物（ABA、BAB、ABABA和BABAB）中各个区域的桥接分数，并与它们的柔性对应物进行了比较。一般来说，我们观察到，对于三嵌段和五嵌段共聚物，使其中一个嵌段可结晶会促进该组分中的桥接，同时减少另一个不可结晶组分中的桥接。此外，三嵌段和五嵌段共聚物中的桥接分数在数量上相似，只是通过可桥接单元的体积分数进行了归一化。
