Complex micelles from the self-assembly of coil-rod-coil amphiphilic triblock copolymers in selective solvents
Complex micelles from the self-assembly of coil-rod-coil amphiphilic triblock copolymers in selective solvents
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DOI：
10.1039/b926370e
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发表时间：
2010-03
期刊：
影响因子：
3.4
通讯作者：
P. He;Xuejin Li;M. Deng;Tao Chen;Haojun Liang
中科院分区：
文献类型：
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作者：
P. He;Xuejin Li;M. Deng;Tao Chen;Haojun Liang
我们报道了一个广泛的模拟研究自发形成的复杂胶束从线圈棒线圈两亲性三嵌段共聚物在稀溶液中的溶剂选择性。两亲性分子由每侧上的一个亲水性嵌段和中间的疏水性嵌段构建。通过在疏水块中添加三个连续颗粒之间的角度的键弯曲势来引入杆块的刚性。刚性棒嵌段的引入导致自组装的微结构和它们相应的性能不同于那些由完全柔性的两亲性分子在相同的条件下构建的。通过改变溶剂的选择性，定义在溶剂和亲水/疏水性粒子之间的排斥相互作用，我们发现，聚集形态的变化，从矛状胶束的球形和圆柱形胶束，细长胶束，然后环状的环形胶束，揭示了溶剂的选择性是一个关键因素，决定聚集形态。此外，我们观察到，从线圈-棒-线圈两亲性三嵌段共聚物的环形胶束的形成通过生长途径进行，这是完全不同的，从传统的环形胶束聚结途径中观察到的完全灵活的两亲性三嵌段共聚物系统的自组装过程。同样研究了由具有完全柔性疏水和刚性棒疏水嵌段的两亲性三嵌段共聚物形成的环形胶束中的链堆积。模拟结果表明，在环状胶束中，刚性杆中间块仅采用伸展构象，而柔性线圈中间块可以同时采用折叠和伸展构象。这些结果表明，在两亲分子的键弯曲势是一个有效的和相对简单的方法来模拟的线圈-棒-线圈的两亲性嵌段共聚物的行为。
We report an extensive simulation study on the spontaneous formation of complex micelles from coil-rod-coil amphiphilic triblock copolymers in dilute solution resulting from solvent selectivity. The amphiphilic molecule is built from one hydrophilic block on each side and a hydrophobic block in the middle. The rigidity of the rod block is introduced by adding a bond-bending potential of the angle among three subsequent particles in the hydrophobic block. The incorporation of rigid-rod block into the amphiphilic block copolymer results in the self-assembled microstructures and their corresponding properties that differ from those built from fully flexible amphiphilic molecules with the same conditions. By changing the selectivity of solvents, defined in terms of the repulsive interactions between the solvent and the hydrophilic/hydrophobic particles, we find that the aggregation morphology changes from bundle-like micelles to spherical and cylindrical micelles to elongated micelles and then to ring-like toroidal micelles, revealing that the selectivity of solvents is a key factor that determines aggregation morphology. In addition, we observe that the formation of toroidal micelles from coil-rod-coil amphiphilic triblock copolymers proceeds via the growth pathway, which is quite distinct from the conventional toroidal micelle coalescence pathway observed in the self-assembling process of fully flexible amphiphilic triblock copolymer systems. Chain packing in toroidal micelles formed from amphiphilic triblock copolymers with fully flexible hydrophobic and rigid-rod hydrophobic blocks is likewise investigated. The simulation results show that the rigid-rod middle blocks adopt only extended conformations while flexible-coil middle blocks can adopt both folded and extended conformations in toroidal micelles. These findings demonstrate that the bond-bending potential in amphiphilic molecules is an effective and relatively simple method to model the behavior of coil-rod-coil amphiphilic block copolymers.