纳米粒子驱动受限环境下两嵌段共聚物/均聚物混合体系的自组装行为

Phase Behaviors of Diblock Copolymer/Homopolymer System under Confinement Driven by Nanoparticles

采用含时金兹堡-朗道理论(time-dependent ginzburg-landau theory,简称TDGL)方法研究了纳米粒子(nanoparticles,简称NPs)掺杂的两嵌段共聚物/均聚物(AB/C)共混体系在球形受限下的自组装行为.在不同球形受限条件下,两嵌段共聚物/均聚物共混体系形成了多种丰富的形貌,如双螺旋结构、单螺旋结构、层状结构和洋葱环状结构等.当在以上前3种体系中掺杂纳米粒子后,体系结构发生了很大的变化.详细研究了纳米粒子的浓度和浸润强度对以上结构的影响.研究结果表明,通过调控纳米粒子的浓度和浸润性质,该共混体系实现了双螺旋结构→层状结构,单螺旋结构→双螺旋结构,层状结构→单螺旋结构等多种取向序的转变.对于洋葱环状结构,纳米粒子的加入对体系这一结构的影响不大.

We investigate the phase behaviors of nanoparticles/AB diblock copolymer/C homopolymer system confined in a sphere. The nanoparticles are attracted to the B block, and are neutral toward the A block, monomers A, B, and C are incompatible with each other. All of them are confined in a hard sphere, and the sphere surface is neutral. First, we investigate the phase behaviors of the diblock copolymer/homopolymer confined in a hard sphere. Various ordered morphologies can be formed in the mixture by adjusting the composition ratio and the confining environment. The C component always forms a shell-shaped structure in the outer sphere which encloses the AB diblock copolymer. The AB diblock copolymer shows a variety of morphologies within the sphere, such as the double helix structure（SI）, the single helix structure（SII）, the lamellae structure（SIII）, and the onion ring structure（SIV）. In this study, we add nanoparticles（NPs） of different nature at various concentrations to the above four types of the structures to investigate their effect on the polymer system. For the SI structure, when the particle concentration（cp） is 0.05 ≤ cp ≤ 0.15, and the strength of wetting（g） is 0.005 ≤ g 〈 0.03, an ordered transformation from the double helix structure to the lamellar structure occurs. For the SII structure, when the particle concentration is 0.05≤ cp ≤ 0.1, and the strength of wetting is 0.01 ≤ g 〈 0.015, an ordered transformation from the single helix structure to the double helix structure occurs. For the SIII structure, when the particles concentration is 0.05 ≤ cp ≤ 0.15, and the strength of wetting is 0.005 ≤ g 〈 0.04, an ordered transformation from the lamellar structure to the single helix structure occurs. For the SIV structure, the addition of NPs has little effect on the phase morphology of the system. The results provide a method of controlling polymer self-assembly for experimental studies.