Molecular reorganization of rod-coil diblock copolymers at the air-water interface.
Molecular reorganization of rod-coil diblock copolymers at the air-water interface.
复制标题
DOI：
10.1021/la060844h
复制
发表时间：
2006-06
期刊：
影响因子：
--
通讯作者：
Jie Zhang;H. Cao;X. Wan;Qifeng Zhou
中科院分区：
文献类型：
--
作者：
Jie Zhang;H. Cao;X. Wan;Qifeng Zhou
由柔性聚环氧乙烷（PEO）和棒状聚{（+）-2，5-双[4 '-（（S）-2-甲基丁氧基）苯基]苯乙烯}（PMBPS）组成的两亲性棒状-螺旋状二嵌段共聚物在空气-水界面形成有序单分子膜。用原子力显微镜（AFM）研究了不同表面压力下用LB法转移到云母基底上的单分子膜的结构。对于PEO（104）-b-PMBPS（17）共聚物（下标表示每个嵌段的数均聚合度），观察到在可变表面压力下的分子重组的完整谱。LB单分子膜的球形表面聚集体在聚合物溶液沉积后的溶剂蒸发过程中自发形成。连续压缩导致共聚物的煎饼到刷子构象转变，PEO链从空气-水界面脱附并进入水亚相。棒块的有效含量从零压力下的61%连续变化到单层崩溃开始时的93%，从而引发分子重组。结果，观察到随着表面压力的增加，单个球形聚集体聚结成长圆柱形聚集体。对于一系列嵌段共聚物PEO（104）-b-PMBPS（m）（）（m = 17，30，45，53），随着棒状含量从61%增加到83%，在零压下，球状聚集体的形态逐渐向取向有序的长柱状聚集体转变，在不同的压力下，PEO（104）-b-PMBPS（17）对棒块有效含量的依赖性相似。与线团嵌段共聚物PEO-b-PS相比，棒状-线团嵌段共聚物PEO-b-PMBPS表现出明显的结构重组行为，其中棒状嵌段的取向可能起着重要的作用。
Amphiphilic rod-coil diblock copolymers consisting of flexible poly(ethylene oxide) (PEO) and rodlike poly{(+)-2,5-bis[4'-((S)-2-methylbutoxy)phenyl]styrene} (PMBPS) with predominant hydrophobic contents formed ordered monolayers at the air-water interface. The structures of monolayers transferred to a mica substrate at different surface pressures by the Langmuir-Blodgett method were investigated by atom force microscopy (AFM). For PEO(104)-b-PMBPS(17) copolymer (the subscripts denote the number-averaged polymerization degree of each block), a complete spectrum of molecular reorganization at variable surface pressures was observed. Spherical surface aggregates of LB monolayers were spontaneously formed during the solvent evaporation after the deposition of polymer solution. Continuous compression led to the pancake-to-brush conformation transition of the copolymer that PEO chains desorbed from the air-water interface and went into the water subphase. The effective content of the rod block changed continuously from 61% at zero pressure to 93% at the start of the monolayer collapse, igniting the molecular reorganization. As a result, coalescence of individual spherical aggregates into long cylindrical aggregates with an increase of the surface pressure was observed. For a series of block copolymers PEO(104)-b-PMBPS(m)() (m = 17, 30, 45, 53), as the rod contents increased from 61% to 83%, the morphological transition from spherical aggregates to long cylindrical aggregates in orientational order developed at zero pressure, which showed a similar dependence on the effective contents of the rod block to PEO(104)-b-PMBPS(17) at different pressures. In comparison to coil-coil block copolymers PEO-b-PS, the rod-coil block copolymers PEO-b-PMBPS exhibited distinct structure reorganization behavior, in which the orientation of rod block might play an important role.