柱状相聚苯乙烯-b-聚乳酸的合成及引导组装

Synthesis and Directed Self-assembly of Cylinder-Forming Poly (styrene-b-lactide) Block Copolymers

设计并合成了2种柱状相结构的聚苯乙烯-b-聚乳酸(PS-b-PLA)两嵌段共聚物,并表征了它们在化学图案上的引导自组装行为。在辛酸亚锡(Sn(Oct)_2)催化下,采用羟基官能化的聚苯乙烯(PS-OH)大分子引发剂分别引发外消旋丙交酯(rac-LA)和左旋丙交酯(L-LA)开环聚合,制备了两个相对分子质量相近但构型不同的PS-b-PLA:PS-b-PDLLA和PS-b-PLLA。通过核磁共振波谱仪(NMR)、凝胶渗透色谱仪(GPC)、示差扫描量热仪(DSC)、热重分析仪(TGA)、小角X射线衍射仪(SAXS)等测试手段对两个嵌段共聚物的性质进行了表征。然后,将PS-b-PDLLA和PS-b-PLLA薄膜在六方点阵化学图案模板上加热引导自组装,得到长程有序排列的六方柱状相结构。相对于柱状相的PS-b-PLLA,柱状相的PS-b-PDLLA具有较大的拉伸比例,可以在更大的周期范围内组装出规整的六方结构。这一结果与层状相PS-b-PDLLA和PS-b-PLLA薄膜在线性化学图案上组装的结果相似。

Two cylinder-forming poly（styrene- b -lactide）s, poly（styrene- b - D,L -lactide）（PS- b -PDLLA） and poly（styrene- b - L -lactide））（PS- b -PLLA）, with similar domain sizes（ L O ） were synthesized using ring opening polymerization（ROP） of lactide monomers from hydroxy-terminated polystyrene（PS-OH） with zinc octoate（ Sn（Oct） 2 ） as the catalyst and characterized by nuclear magnetic resonance spectroscopy（NMR）, gel permeation chromatography（GPC）, differential scanning calorimetry（DSC）, thermal gravimetric analyzer（TGA） and small-angle X-ray scattering（SAXS）. Thin films of PS- b -PDLLA and PS- b -PLLA were directed to assemble on hexagonal arrays of spot chemical patterns with a range of pattern periods（ L S ） under thermal annealing . SEM analysis of the two assembled films revealed that long-range ordered perpendicularly-oriented hexagonal-array cylinders were obtained in both films. The range of L S window for defect-free assembly of perpendicular cylinders was larger in PS- b -PDLLA films than that in PS- b -PLLA films, which is similar to the assembly behavior of lamellar-forming PS- b -PLA on stripe chemical patterns.