Abstract:

The dissipative particle dynamics (DPD) simulations were performed to study the self-assembly behavior of amphiphilic nanoparticles in selective solvents. The effects of various parameters, including solvent selectivity, the length of grafting polymers and the grafting ratio of hydrophilic polymer to hydrophobic polymer, were studied. Then, the phase diagram of self-assembled morphology was constructed. A rich variety of morphologies, ranging from spherical aggregates, rod-like aggregates, two-dimensional membrane, and nanopore membrane were obtained as increasing the concentration of amphiphilic nanoparticles. Furthermore, the amphiphilic nanoparticles tend to self-assemble into the layered nano-aggregates when the solvent quality is poor (i.e.,a_S-HL=40k_BT/R_c, a_S-HB=50×k_BT/R_c), and the porous networked aggregates were observed at high concentration of amphiphilic nanoparticles. The simulation results also revealed that the self-assembled aggregates are largely controlled by the concentration of amphiphilic nanoparticles and the ratios of grafting hydrophilic polymers to grafting hydrophobic polymers. In view of the rich self-assembly behavior of the parental nanoparticles, it has great potential application value in gas separation, detection, drug loading, catalyst carrier and other fields.

Key words: nanoparticles, dissipative particle dynamics, simulation, self-assembly, solvent

摘要：

接枝聚合物纳米颗粒在构筑多级功能性纳米材料方面具有很大潜力，但其在选择性溶剂中自组装相图却鲜见报道。利用耗散粒子动力学模拟研究了溶剂选择性、接枝聚合物链长度以及亲水、疏水聚合物链比例等因素对双亲纳米颗粒自组装行为的影响，并绘制了自组装形态相图。结果显示，随着浓度的增大，双亲纳米颗粒逐渐自组装成球状、棒状、二维膜、纳米膜孔等丰富纳米结构。不仅如此，溶剂与亲水、疏水聚合物相容性差异较小时（a_S-HL=40k_BT/R_c，a_S-HB=50k_BT/R_c），双亲纳米颗粒自组装形成层状纳米结构，在较高浓度时，形成规则的多孔网络结构。研究发现，双亲纳米颗粒浓度和接枝聚合物的链长以及亲水、疏水聚合物链比例是调控双亲纳米颗粒自组装形态的关键因素。鉴于双亲纳米颗粒丰富的自组装行为，它在气体分离、检测、载药、催化剂载体等领域有着很大的潜在应用价值。

关键词: 纳米粒子, 耗散粒子动力学, 模拟, 自组装, 溶剂