Bessif Brahim, Pfohl Thomas, Reiter Günter
Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany.
Freiburg Materials Research Center (FMF), Albert-Ludwigs-Universität, 79104 Freiburg, Germany.
Polymers (Basel). 2021 May 21;13(11):1676. doi: 10.3390/polym13111676.
We examined the formation of self-seeded platelet-like crystals from polystyrene--polyethylene oxide (PS--PEO) diblock copolymers in toluene as a function of polymer concentration (c), crystallization temperature (TC), and self-seeding temperature (TSS). We showed that the number (N) of platelet-like crystals and their mean lateral size (L) can be controlled through a self-seeding procedure. As (homogeneous) nucleation was circumvented by the self-seeding procedure, N did not depend on TC. N increased linearly with c and decayed exponentially with TSS but was not affected significantly by the time the sample was kept at TSS. The solubility limit of PS--PEO in toluene (c*), which was derived from the linear extrapolation of Nc→ 0 and from the total deposited mass of the platelets per area (MCc→0), depended on TC. We have also demonstrated that at low N, stacks consisting of a (large) number (η) of uniquely oriented lamellae can be achieved. At a given TC, L was controlled by N and η as well as by ∆c=c-c∗. Thus, besides being able to predict size and number of platelet-like crystals, the self-seeding procedure also allowed control of the number of stacked lamellae in these crystals.
我们研究了聚苯乙烯-聚环氧乙烷（PS-PEO）二嵌段共聚物在甲苯中形成自晶种血小板状晶体的过程，该过程是聚合物浓度（c）、结晶温度（TC）和自晶种温度（TSS）的函数。我们表明，血小板状晶体的数量（N）及其平均横向尺寸（L）可以通过自晶种程序来控制。由于自晶种程序规避了（均匀）成核，N不依赖于TC。N随c线性增加，随TSS指数衰减，但不受样品在TSS下保持时间的显著影响。PS-PEO在甲苯中的溶解度极限（c*），由Nc→0的线性外推和每单位面积血小板的总沉积质量（MCc→0）得出，取决于TC。我们还证明，在低N时，可以获得由大量（η）独特取向的片层组成的堆叠结构。在给定的TC下，L由N和η以及∆c = c - c*控制。因此，除了能够预测血小板状晶体的尺寸和数量外，自晶种程序还允许控制这些晶体中堆叠片层的数量。
