Liberman-Martin Allegra L, Chang Alice B, Chu Crystal K, Siddique Radwanul H, Lee Byeongdu, Grubbs Robert H
Schmid College of Science and Technology, Chapman University, Orange, California 92866, United States.
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
ACS Macro Lett. 2021 Dec 21;10(12):1480-1486. doi: 10.1021/acsmacrolett.1c00579. Epub 2021 Nov 11.
The self-assembly of poly(dimethylsiloxane)--poly(trimethylene carbonate) (PDMS--PTMC) bottlebrush block polymers was investigated under different processing conditions. Small-angle X-ray scattering (SAXS) and UV/Visible spectroscopy provided insight into the self-assembly and structure in response to heating and applied pressure. In the absence of applied pressure (i.e., before annealing), the PDMS--PTMC bottlebrush block polymers are white solids and adopt small, randomly oriented lamellar grains. Heating the materials to 140 °C in the absence of applied pressure appears to "lock in" the isotropic, short-range-ordered state, preventing the formation of the long-range-ordered lamellar structure responsible for photonic properties. Applying modest anisotropic pressure (3 psi) between parallel plates at ambient temperature orients the short-range lamellar grains; however, applied pressure alone does not produce long-range order. Only when the bottlebrush block polymers were heated (>100 °C) under modest pressure (3 psi) were long-range-ordered photonic crystals formed. Analysis of the SAXS data motivated analogies to liquid crystals and revealed the potential self-assembly pathway. These results provide insight into the structure and self-assembly of bottlebrush block polymers with low glass transition temperature side chains in response to different processing conditions.
研究了聚（二甲基硅氧烷）-聚（碳酸三亚甲基酯）（PDMS-PTMC）瓶刷状嵌段聚合物在不同加工条件下的自组装情况。小角X射线散射（SAXS）和紫外/可见光谱提供了对加热和施加压力时自组装及结构的深入了解。在没有施加压力的情况下（即退火前），PDMS-PTMC瓶刷状嵌段聚合物为白色固体，呈现出小的、随机取向的层状晶粒。在没有施加压力的情况下将材料加热到140°C似乎会“锁定”各向同性的短程有序状态，阻止形成负责光子特性的长程有序层状结构。在室温下在平行板之间施加适度的各向异性压力（3 psi）会使短程层状晶粒取向；然而，仅施加压力不会产生长程有序。只有当瓶刷状嵌段聚合物在适度压力（3 psi）下加热（>100°C）时，才会形成长程有序的光子晶体。对SAXS数据的分析促使与液晶进行类比，并揭示了潜在的自组装途径。这些结果提供了对具有低玻璃化转变温度侧链的瓶刷状嵌段聚合物在不同加工条件下的结构和自组装的深入了解。
