Polymer crystallization is a multi-stage process and generally takes place through the metastable intermediate structure or mesophase. However, mesopahse is difficult to be experimentally detected during crystallization and its formation mechanism is not well understood. Herein, we find that the formation of mesopahse is facilitated in the crystallization of stereocomplexable block polymers. We use the poly(L-lactic acid)-poly(ethylene glycol)-poly(L-lactic acid) (PLLA-PEG-PLLA) and poly(D-lactic acid)-poly(ethylene glycol)-poly(D-lactic acid) (PDLA-PEG-PDLA) as the stereocomplexable pair and investigate the synergetic effects of copolymer composition and PLLA/PDLA stereocomplexation on the mesophase formation in the PLLA-PEG-PLLA/PDLA-PEG-PDLA 1/1 blends. Intriguingly, the stereocomplexable blend having the high PEG fraction forms the unique homocrystalline mesophase at the low crystallization temperature (T_c, 70–120 °C) but the usual α-form homocrystals (HCs) at high T_c (120–160 °C), except for the stereocomplexes (SCs). However, the crystalline structure of PLLA-PEG-PLLA/PDLA-PEG-PDLA blend with low PEG fraction is similar as the PLLA/PDLA blend; it crystallizes in the mixture of α(α′)-HCs + SCs at T_c = 70–160 °C. The homocrystalline mesophase formed in stereocomplexable blend is metastable and reorganizes into the more thermally-stable α-HCs and SCs during heating. We propose that the mesophase formation in enantiomeric blend is resulted by the constrained effects induced by the stereocomplexation and microphase separation of block copolymers.

聚合物结晶是一个多阶段的过程，通常通过亚稳的中间结构或中间相进行。但是，美索帕西很难在结晶过程中进行实验检测，其形成机理还不清楚。在本文中，我们发现，在可立体络合的嵌段聚合物的结晶中，美索帕西的形成变得容易。我们使用聚（L-乳酸）-聚（乙二醇）-聚（L-乳酸）（PLLA-PEG-PLLA）和聚（D-乳酸）-聚（乙二醇）-聚（D-乳酸（PDLA-PEG-PDLA）作为立体可络合对，并研究共聚物组成和PLLA / PDLA立体络合对PLLA-PEG-PLLA / PDLA-PEG-PDLA 1/1共混物中间相形成的协同作用。有趣的是T _c，70–120°C），但在高T _c（120–160°C）时，除了立体配合物（SCs）以外，通常是α型均晶（HCs ）。但是，PEG含量低的PLLA-PEG-PLLA / PDLA-PEG-PDLA共混物的晶体结构与PLLA / PDLA共混物相似。它在T _c  = 70–160°C时在α（α'）-HCs + SCs的混合物中结晶。在可立体络合的共混物中形成的均相中间相是亚稳态的，并在加热过程中重组为更热稳定的α-HCs和SC。我们提出对映体共混物的中间相形成是由嵌段共聚物的立体配合和微相分离引起的约束效应引起的。