Hierarchical Structures in Thin Films of Miktoarm Star Polymers: Poly(n-hexyl isocyanate)(12K)-Poly(ε-caprolactone)1-3(5K)
Hierarchical Structures in Thin Films of Miktoarm Star Polymers: Poly(n-hexyl isocyanate)(12K)-Poly(ε-caprolactone)1-3(5K)
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DOI：
10.1021/ma501695b
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发表时间：
2014-11-11
期刊：
影响因子：
5.5
通讯作者：
Ree, Moonhor
中科院分区：
文献类型：
--
作者：
Kim, Young Yong;Jung, Sungmin;Ree, Moonhor
研究了一系列杂臂星星型聚合物[聚异氰酸正己酯（12 K）][聚己内酯（13）（5 K）]（PHICPCL 13）（由一个刚性的自组装PHIC臂和一到三个柔性的可结晶PCL臂组成）的热性能和纳米薄膜形貌。杂臂聚合物在高达180 ℃下是稳定的。PHIC和PCL臂组件在溶液浇铸、干燥和后甲苯退火过程中经历相分离，形成有趣但非常复杂的薄膜形态。第一次使用同步辐射掠入射X射线散射（GIXS）测量和定量数据分析，详细检查所得到的薄膜形貌。所有的miktoarm星星聚合物膜形成垂直良好取向的层状结构，而不考虑PCL臂的数量和长度。这些结构与在具有相当体积分数的传统柔性二嵌段共聚物膜中通常观察到的圆柱形结构截然不同。各个PHIC和PCL层状域自组装以形成它们各自的形态结构。的PHIC lamadium由水平和垂直的多层结构域的混合物，如在PHIC均聚物膜中观察到的。PCL层状形成流苏状胶束状晶体和/或高度不完美的折叠晶体，其与在由典型折叠层状晶体组成的PCL均聚物膜中发现的结构显著不同。这些PCL晶体是由垂直和水平正交晶格的混合物形成的。总体而言，GIXS分析表明，表征薄膜中的分级结构的参数显著依赖于PCL臂的数量和长度及其结晶特性以及PHIC臂的链刚性和多层结构形成特性。
A series of miktoarm star polymers, [poly(n-hexyl isocyanate)(12K)][poly(epsilon-caprolactone)(13)(5K)] (PHICPCL13) (composed of a rigid self-assembling PHIC arm and one to three flexible crystallizable PCL arms), were investigated to examine the polymers thermal properties and nanoscale thin film morphologies. The miktoarm polymers were stable up to 180 degrees C. The PHIC and PCL arm components underwent phase separation during the solution casting, drying, and post toluene-annealing processes, forming interesting but very complex thin film morphologies. The resulting thin film morphologies were examined in detail for the first time using synchrotron grazing incidence X-ray scattering (GIXS) measurements and quantitative data analysis. All of the miktoarm star polymer films formed vertically well-oriented lamellar structures, regardless of the number and length of PCL arms. These structures were quite different from the cylindrical structures commonly observed in conventional flexible diblock copolymer films having comparable volume fractions. The individual PHIC and PCL lamellar domains self-assembled to form their own respective morphological structures. The PHIC lamellae consisted of a mixture of horizontal and vertical multibilayer structure domains, as observed in the PHIC homopolymer film. The PCL lamellae formed fringed micelle-like crystals and/or highly imperfect folded crystals that differed significantly from the structures found in a PCL homopolymer film composed of typical folded lamellar crystals. These PCL crystals were formed with a mixture of vertical and horizontal orthorhombic lattices. Overall, the GIXS analysis revealed that the parameters that characterized the hierarchical structures in the thin films depended significantly on the number and length of the PCL arm and its crystallization characteristics as well as the chain rigidity and multibilayer structure formation characteristics of the PHIC arm.