Patchy Micelles Based on Coassembly of Block Copolymer Chains and Block Copolymer Brushes on Silica Particles

Abstract

Patchy particles are a type of colloidal particles with one or more well-defined patches on the surfaces. The patchy particles with multiple compositions and functionalities have found wide applications from the fundamental studies to practical uses. In this research patchy micelles with thiol groups in the patches were prepared based on coassembly of free block copolymer chains and block copolymer brushes on silica particles. Thiol-terminated and cyanoisopropyl-capped polystyrene-block-poly(N-isopropylacrylamide) block copolymers (PS-b-PNIPAM-SH and PS-b-PNIPAM-CIP) were synthesized by reversible addition-fragmentation chain transfer polymerization and chemical modifications. Pyridyl disulfide-functionalized silica particles (SiO2-SS-Py) were prepared by four-step surface chemical reactions. PS-b-PNIPAM brushes on silica particles were prepared by thiol-disulfide exchange reaction between PS-b-PNIPAM-SH and SiO2-SS-Py. Surface micelles on silica particles were prepared by coassembly of PS-b-PNIPAM-CIP and block copolymer brushes. Upon cleavage of the surface micelles from silica particles, patchy micelles with thiol groups in the patches were obtained. Dynamic light scattering, transmission electron microscopy, and zeta-potential measurements demonstrate the preparation of patchy micelles. Gold nanoparticles can be anchored onto the patchy micelles through S-Au bonds, and asymmetric hybrid structures are formed. The thiol groups can be oxidized to disulfides, which results in directional assembly of the patchy micelles. The self-assembly behavior of the patchy micelles was studied experimentally and by computer simulation.

From Self-Assembled Monolayers to Coatings: Advances in the Synthesis and Nanobio Applications of Polymer Brushes

“…Examples include the use of crosslinked or multiple-point grafted poly(glycidyl methacrylate) (PGMA) thin coatings or epoxy terminated silane SAMs to attach amine-or acid-terminated polymers [62][63][64][65][66][67][68], a reductive alkylation reaction between amine-functionalized surface and aldehyde-terminated polymers to form an imine bond which is subsequently reduced [69,70], Au-S bond formation between thiol-terminated polymer and Au surface [71,72], thiol-disulfide exchange reaction using thiol-terminated block copolymers to prepare for cleavable polymer brushes on silica particles [73,74], an amidation reaction of N-hydroxysuccinamde protected carboxylic acid terminated polymers and amine functionalized SAMs on surface [75], Diels-Alder ligation reaction between cyclopentadiene and maleimide [76], and a condensation reaction between silane-terminated polymers and silanol groups on an oxide surface [77].…”

Protein Nanogels with Temperature-Induced Reversible Structures and Redox Responsiveness

“…The disulfides are readily reduced to thiols within a reducing environment resulting in the cleavage of the disulfide bonds. , In addition to the thermal response provided by PDEGMA chains, the nanogels cross-linked by disulfide bonds are dissociated upon exposure to reductive environments. Herein, the effect of reductant on the size of nanogels is investigated.…”

In situ fabrication of PHEMA–BSA core–corona biohybrid particles

“…The disulfides are readily reduced to thiols within a reducing environment resulting in cleavage of the disulfide bonds. 47,48 Disulfides can be cleaved efficiently by DTT. 48 In this research we investigated the change in the morphology of the core-corona particles upon addition of DTT.…”