Ma Mingchao, Guo Yunlong
University of Michigan , Shanghai Jiao Tong University Joint Institute , Shanghai 200240 , China.
School of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , China.
J Phys Chem B. 2019 Mar 14;123(10):2448-2453. doi: 10.1021/acs.jpcb.8b12565. Epub 2019 Mar 4.
This letter presents an accelerated physical aging of polystyrene (PS) blocks in polystyrene- block-poly(methyl methacrylate) (PS- b-PMMA) diblock copolymers under hard confinement. The three-dimensional hard nanoconfinement was provided by the PMMA component owing to its high elasticity and was formed via self-assembled microphase separation. Aging was observed by measuring enthalpy recovery of the PS blocks in the copolymers for which the degree of polymerization ( N) of PS blocks is fixed, whereas the N of PMMA blocks varies. Our results demonstrate that the aging speed of the PS blocks can increase by a factor of three to that of the neat PS as the N of PMMA blocks increases. Therefore, the hard confinement accelerates physical aging of the PS blocks, i.e., the relatively soft component in the copolymer.
这封信展示了在硬限域条件下，聚苯乙烯-嵌段-聚（甲基丙烯酸甲酯）（PS-b-PMMA）二嵌段共聚物中聚苯乙烯（PS）嵌段的加速物理老化。由于聚甲基丙烯酸甲酯（PMMA）组分具有高弹性，通过自组装微相分离形成了三维硬纳米限域。通过测量共聚物中PS嵌段的焓恢复来观察老化，其中PS嵌段的聚合度（N）固定，而PMMA嵌段的N变化。我们的结果表明，随着PMMA嵌段的N增加，PS嵌段的老化速度可以比纯PS提高三倍。因此，硬限域加速了PS嵌段的物理老化，即共聚物中相对较软的组分的老化。
