Controlling the self-assembly pathways of amphiphilic block copolymers into vesicles
Controlling the self-assembly pathways of amphiphilic block copolymers into vesicles
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DOI：
10.1039/c2sm25281c
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发表时间：
2012-07
期刊：
影响因子：
3.4
通讯作者：
Mengying Xiao;Guangjie Xia;Rong Wang;D. Xie
中科院分区：
文献类型：
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作者：
Mengying Xiao;Guangjie Xia;Rong Wang;D. Xie
囊泡和膜的性质在再生活细胞的自然环境中起着关键作用，如营养运输和DNA保护。采用耗散粒子动力学方法研究了由疏水-疏水-亲水结构组成的两亲性嵌段共聚物自组装过程中的形态演化阶段。通过控制疏水性/亲水性嵌段比、聚合物-溶剂相互作用和聚合物浓度，可以获得两种独特的中间状态：（1）双层型膜，例如棒状、盘状或碗状胶束（机制I），（2）源自重排的亲水性嵌段在合并过程中移动到中心或捕获的亲水性嵌段的半囊泡（机制II）。此外，在这两种途径之间的过渡期间，囊泡通过中间途径形成。具体地说，而不是典型的机制I或机制II，亲水块逐渐向一些不规则的球形胶束的中心扩散，然后成为完整的囊泡。最重要的是，我们表明，两个因素，块的疏水性程度和粘合剂两亲物碰撞的概率被认为是至关重要的控制囊泡形成机制。因此，内部疏水性珠粒的分离和外部亲水性珠粒的吸引力之间的关键平衡极大地影响了两亲性嵌段共聚物从一种机制到另一种机制的自组装成囊泡的途径。此外，我们证明了当亲水性嵌段向中心移动形成空腔时，它们可以随机移动并保持平衡的数量。
Vesicles and membrane properties play critical roles in reproducing the natural environment of living cells such as nutrient transport and DNA protection. We report how to control the morphology evolutionary stages of the self-assembly of amphiphilic block copolymers composed of hydrophilic–hydrophobic–hydrophilic structure using dissipative particle dynamics method. Two unique intermediate states are obtained by controlling the hydrophobic/hydrophilic block ratio, polymer–solvent interaction, and polymer concentration: (1) bilayer-type membrane such as rod-like, disk-like, or bowl-like micelle (mechanism I), (2) semivesicle originating from the rearranged hydrophilic blocks movement into the center or the trapped hydrophilic blocks during merging (mechanism II). Additionally, during the transition period between these two pathways, vesicles are formed through an in-between pathway. Specifically, instead of the typical mechanism I or mechanism II, hydrophilic blocks gradually diffuse toward the center of some irregular spherical micelles, and then become full vesicles. Most importantly, we show that two factors, the degree of hydrophobicity of the blocks and the probability of the adhesive amphiphile collisions are thought to be of key importance to control the vesicle-formation mechanisms. As a consequence, a crucial balance between the segregation of inner-hydrophobic beads and the attraction of outer-hydrophilic beads drastically affects the self-assembly pathways of amphiphilic block copolymer into vesicles from one mechanism over the other. Furthermore, we demonstrate that when the hydrophilic blocks move toward the center to form a cavity, they can move in randomly and maintain a balanced quantity.