title: Elucidating dominant pathways of the nano-particle self-assembly process.
abstract: Self-assembly processes play a key role in the fabrication of functional nano-structures with widespread application in drug delivery and micro-reactors. In addition to the thermodynamics, the kinetics of the self-assembled nano-structures also play an important role in determining the formed structures. However, as the self-assembly process is often highly heterogeneous, systematic elucidation of the dominant kinetic pathways of self-assembly is challenging. Here, based on mass flow, we developed a new method for the construction of kinetic network models and applied it to identify the dominant kinetic pathways for the self-assembly of star-like block copolymers. We found that the dominant pathways are controlled by two competing kinetic parameters: the encounter time Te, characterizing the frequency of collision and the transition time Tt for the aggregate morphology change from rod to sphere. Interestingly, two distinct self-assembly mechanisms, diffusion of an individual copolymer into the aggregate core and membrane closure, both appear at different stages (with different values of Tt) of a single self-assembly process. In particular, the diffusion mechanism dominates the middle-sized semi-vesicle formation stage (with large Tt), while the membrane closure mechanism dominates the large-sized vesicle formation stage (with small Tt). Through the rational design of the hydrophibicity of the copolymer, we successfully tuned the transition time Tt and altered the dominant self-assembly pathways.
authors.affiliation: Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. xuhuihuang@ust.hk.
authors.forename: Xiangze
authors.initials: X
authors.lastname: Zeng
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Qin
authors.initials: Q
authors.lastname: Qiao
authors.forename: Lizhe
authors.initials: L
authors.lastname: Zhu
authors.forename: Zhong-Yuan
authors.initials: ZY
authors.lastname: Lu
authors.forename: Xuhui
authors.initials: X
authors.lastname: Huang