Dynamic self-assembly of photo-switchable nanoparticles
Dynamic self-assembly of photo-switchable nanoparticles
复制标题
DOI：
10.1039/c1sm06662e
复制
发表时间：
2012-01-01
期刊：
影响因子：
3.4
通讯作者：
de la Cruz, Monica Olvera
中科院分区：
文献类型：
--
作者：
Jha, Prateek K.;Kuzovkov, Vladimir;de la Cruz, Monica Olvera
用光可切换配体官能化的纳米颗粒可以通过受控的光暴露组装成广泛的结构。特别地，交替曝光提供了控制各种尺寸和对称性的组件的形成的手段。在这里，我们使用缩放参数和动力学Monte Carlo模拟来研究在周期性照射的光开关纳米粒子的溶液中可逆聚集体的演变。尺度估计的特征尺寸和团聚体的平均分离同意模拟。动力学蒙特卡罗方法中的跃迁几率是从扩散过程的重整化主方程导出的。对纳米粒子系统的模拟，通过Lennard-Jones对势相互作用，根据曝光量将其特性从排斥变为吸引，表明在低有效温度下（吸引力远高于热能）粒子的缓慢扩散导致形成小的“动力学冻结”聚集体。另一方面，聚集不会发生在高有效温度下，其中的吸引力与热能相当。在有效温度的中间范围内，“波动”聚集体形成，可以通过施加特定长度和频率的光脉冲来稳定。聚集体尺寸通过增加填充分数而增加，并且聚集体在高填充分数下经历向网状“网络”的转变。颗粒间相互作用的光控制可以抑制或促进成核和生长，并且可以减少凝胶和玻璃形成。
Nanoparticles functionalized with photo-switchable ligands can be assembled into a broad range of structures by controlled light exposure. In particular, alternating light exposures provide the means to control formation of assemblies of various sizes and symmetries. Here, we use scaling arguments and Kinetic Monte Carlo simulations to study the evolution of reversible aggregates in a solution of periodically irradiated photo-switchable nanoparticles. Scaling estimates of the characteristic size and the mean separation of aggregates agree with the simulations. The transition probabilities in the Kinetic Monte Carlo scheme are derived from a renormalized master equation of the diffusion process. Simulations on a system of nanoparticles, interacting through Lennard-Jones pair potentials that change their character from repulsive to attractive depending on the light exposure, show that the slow diffusion of particles at low effective temperatures (where the attractions are much higher than the thermal energy) results in the formation of small, "kinetically frozen'' aggregates. On the other hand, aggregation does not occur at high effective temperatures, where the attractions are comparable to the thermal energy. In the intermediate range of effective temperatures, "fluctuating'' aggregates form that can be stabilized by applying light pulses of specific lengths and frequencies. The aggregate sizes increase by increasing the packing fraction and the aggregates undergo transition to a percolated "network'' at high packing fractions. Light-control of inter-particle interactions can either inhibit or promote nucleation and growth, and can reduce gel and glass formation.