Structural Engineering in the Self-Assembly of Amphiphilic Block Copolymers with Reactive Additives: Micelles, Vesicles, and Beyond

Abstract

Control of polymer assemblies in solution is of great importance to determine the properties and applications of these polymer nanostructures. We report a novel co-self-assembly strategy to control the self-assembly outcomes of a micelle-forming amphiphilic block copolymer (BCP) of poly­(ethylene oxide) (PEO) and poly­[3-(trimethoxysilyl)­propyl methacrylate] (PTMSPMA), PEO114-b-PTMSPMA228. With a reactive and hydrophobic additive tetraethyl orthosilicate (TEOS), the assembly nanostructures of PEO114-b-PTMSPMA228 are tunable. The swelling of the PTMSPMA block by hydrophobic TEOS increases the hydrophobic-to-hydrophilic ratio that enables a continuous morphological evolution from spherical micelles to vesicles and eventually to large compound vesicles. TEOS that co-hydrolyzes with the PTMSPMA block can further stabilize and fix these hybrid nanostructures. With high TEOS concentrations, these polymer assemblies can be further converted through thermal annealing into unique silica nanomaterials, including nanospheres, hollow nanoparticles with dual shells, and mesoporous silica frameworks that cannot be synthesized through conventional syntheses otherwise.

Role of chain architecture in the solution phase assembly and thermoreversibility of aqueous PNIPAM/silyl methacrylate copolymers

“…22 Because of these properties, responsive polymers with inorganic functionalities have been used to develop systems for a wide range of applications including drug delivery, 2,13,[23][24][25] sensing, 1,26,27 and controlled nano-assemblies. 4,28 Poly(N-isopropyl acrylamide) (PNIPAM) is a thermoresponsive polymer of strong interest for incorporating inorganic functionalities, as the polymer has been studied extensively for a range of applications, including drug delivery 25,29,30 and sensing. [31][32][33] Aqueous PNIPAM solutions have a lower critical solution temperature (LCST) at biologically-relevant temperatures (typically near 35 °C), where the conformation of the chains dramatically changes, leading to phase separation.…”

“…22 Because of these properties, responsive polymers with inorganic functionalities have been used to develop systems for a wide range of applications including drug delivery, 2,13,23–25 sensing, 1,26,27 and controlled nano-assemblies. 4,28…”

Templated synthesis of crystalline mesoporous CeO2 with organosilane-containing polymers: balancing porosity, crystallinity and catalytic activity

“…This is similar to our previous observation on TiO 2 . Polymer templates of PEO 114 -b-PTMSPMA 224 were thermally converted to inorganic silica nanoparticles that are mechanically strong to prevent the overgrowth of CeO 2 crystallites on the frameworks [75]. While the temperature raised beyond the glass transition of silica, the sintering of silica templates would result in the collapse of pores [76].…”

Manipulation of Bowl-Shaped Nanoparticles Self-Assembled from a Bipyridine Pendant Containing Homopolymer

“…18−20 The key factor to precisely control the morphologies of BNPs relies on the regulation of the local viscosity during self-assembly, further promoting the inhomogeneous shrinkage of the "preformed spheres" containing polymer chains, water, and organic solvents. 21,22 Otherwise, large compound micelles (LCMs) are formed.…”