Using dissipative dynamics simulation,we studied self-assembly behavior of(A-g-B)-b-A comb-coil copolymers in selective solvents.The comb-coil copolymers,having two competitive length scales,are able to self-assemble into aggregates of different types,i.e.,type I and type Ⅱ.For the aggregates of type Ⅰ,the phase separation occurs between the solvophobic and solvophilic blocks,which behave as asymmetric graft copolymers.While in the aggregates of type Ⅱ,the phase separation takes place between coil and comb blocks,acting as diblock copolymers.The self-assembly of the comb-coil block copolymers in solvents selective to either graft arms or backbone was investigated.The effects of the number and length of graft arms on the self-assembly behavior were examined.In the solvents selective to graft arms,the comb-coil copolymers tend to assemble into spherical micelles of type Ⅱ,where the comb and coil blocks form the shell and core,respectively.This is due to the fact that the crowd of the comb blocks in the shell can be alleviated by forming high-curvature structures.In addition,such a crowd can also be alleviated by decreasing the length of graft arms and therefore,vesicles were observed when the graft arms are short.In addition,the decrease in the interaction strength between backbone and graft arms (and solvents) favors the formation of the aggregates of type Ⅱ.In the solvents selective to backbones,the comb-coil copolymers incline to form low-curvature aggregates of type Ⅱ,such as disklike micelles and vesicles.By forming low-curvature structures,the rod-like comb blocks can be tightly packed in the cores of the aggregates.When the comb-coil copolymers form the aggregates of type I in both solvents,the morphologies are very sensitive to the length of the graft arms.For example,in solvents selective to graft arms,as the length of graft arms increases,a morphological transformation of large-compound micelle → vesicle → cylindrical micelle → spherical micelle was observed.The simulation results were compared with the available experimental findings reported in the literatures,and an agreement was observed.In addition,the simulations predict some behaviors that have not been observed yet.The present work is helpful for further understanding the competitive self-assembly behavior of the comb-coil copolymers.%梳状-线性共聚物在选择性溶剂中可以自组装形成两种不同类型的聚集体,其中第Ⅰ类的自组装发生在亲、疏溶剂链之间,而第Ⅱ类发生在线性链和梳状亚结构之间.本工作利用耗散粒子动力学方法,分别研究了梳状-线性共聚物在侧链和主链选择性溶剂中形成的这两类聚集体,探讨了侧链长度和侧链数量等对聚集体类型及形貌的影响.研究表明,第Ⅱ类聚集体在侧链长度较短且侧链数量较多时容易形成.将模拟结果与文献报道的实验结果相比较,发现两者能较好地吻合.此外,本研究获得了一些在实验中较难得到的信息,有助于进一步理解梳状-线性共聚物的自组装行为.
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