Semicrystalline multiblock copolymers holding alternatingly crystallizable and noncrystallizable blocks are good thermoplastic elastomers that are commonly processed through strain-induced crystallization. The crystalline microdomains play the role of physical crosslinks in the network of noncrystallizable blocks for high elasticity, and meanwhile their size diversity determines high toughness. We scheduled three integrated steps to study three physical effects of the coexisting noncrystallizable components, i.e. dilution, microphase separation and asymmetric block rigidity, on the size diversity of crystalline microdomains yielded by strain-induced crystallization in multiblock copolymers. We firstly considered the dilution effects in the extremely concentrated and diluted cases presumably generated by concentration fluctuations of crystallizable blocks, as responsible for the large-end and small-end crystalline microdomains, respectively. Our dynamic Monte Carlo simulations of strain-induced crystallization of the extremely concentrated and diluted crystallizable blocks in diblock and tetrablock copolymers demonstrated the dilution effects that the concentrated cases exhibit crystallization similar with bulk homopolymers, but the diluted cases make smaller crystalline microdomains than the cases without stretching, thus strain-induced crystallization in these two cases enhances the size diversity of crystalline microdomains (DOI: 10.1039/D2SM00193D). Hereby in the second step, we further compared the concentrated and diluted cases of strain-induced crystallization with and without microphase separation, and observed that microphase separation influences little to the concentrated cases, but makes more rather than smaller crystalline microdomains in the diluted cases, thus enhances their size diversity in a way different from the dilution effects. Higher extents of microphase separation will however weaken this enhancement. Our observations paved the way towards a better understanding of strain-induced crystallization in thermoplastic elastomers.

含有交替结晶和不可结晶嵌段的半结晶多嵌段共聚物是良好的热塑性弹性体，通常通过应变诱导结晶进行加工。结晶微区在不可结晶嵌段的网络中起到物理交联的作用以获得高弹性，同时它们的尺寸多样性决定了高韧性。我们安排了三个集成步骤来研究共存的不可结晶组分的三种物理效应，即稀释、微相分离和不对称嵌段刚性，对多嵌段共聚物中应变诱导结晶产生的结晶微区尺寸多样性的影响。我们首先考虑了可能由可结晶块的浓度波动产生的极度浓缩和稀释情况下的稀释效应，分别是大端和小端结晶微区的原因。我们对二嵌段和四嵌段共聚物中极度浓缩和稀释的可结晶嵌段的应变诱导结晶的动态蒙特卡罗模拟证明了稀释效应，浓缩的情况表现出与本体均聚物相似的结晶，但稀释的情况比没有的情况产生更小的结晶微区拉伸，因此在这两种情况下应变诱导的结晶增强了结晶微区的尺寸多样性 (DOI: 10.1039/D2SM00193D)。特此在第二步中，我们进一步比较了有和没有微相分离的应变诱导结晶的浓缩和稀释情况，观察到微相分离对浓缩情况影响很小，但在稀释情况下产生更多而不是更小的结晶微区，从而增强了它们的尺寸多样性一种不同于稀释效应的方式。然而，更高程度的微相分离将削弱这种增强。我们的观察为更好地理解热塑性弹性体中的应变诱导结晶铺平了道路。因此以不同于稀释效应的方式增强了它们的尺寸多样性。然而，更高程度的微相分离将削弱这种增强。我们的观察为更好地理解热塑性弹性体中的应变诱导结晶铺平了道路。因此以不同于稀释效应的方式增强了它们的尺寸多样性。然而，更高程度的微相分离将削弱这种增强。我们的观察为更好地理解热塑性弹性体中的应变诱导结晶铺平了道路。