Nanoconfined Photopolymerization in Self-Assembled Glycerol Monooleate, Hydroxyethyl Acrylate, and Water Suprastructures

Abstract

The nanoconfinement of lipid self-assembled structures offers a dynamic environment for chemical reactions. It enables the integration of regents of various polarities, their alignment at the lipid/water interface for regiospecific reactions, and tailored reaction dimensions from restricted diffusion in the nanoconfinement. However, the effects of monomer integration and polymerization on the self-assembly structure and reaction products remain to be fully understood. Here, we report the photoinitiated polymerization of hydroxyethyl acrylate (HEA) within the inverse bicontinuous cubic structure of glycerol monooleate (GMO), yielding biocompatible hybrid materials. The initial structures are formed in bulk and as thin films on silicon wafers through the self-assembly of GMO molecules with water. Using small-angle X-ray scattering (SAXS) and grazing incidence (GI)SAXS, we find that HEA actively integrates into the lipid-water interface, modifying the self-assembled packing geometries. Photopolymerization triggered structural transformations and changes in orientation relative to the substrate surface. Nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography reveal larger polymer sizes and smaller polydispersity under nanoconfined conditions compared to polymerization in water. These findings enhance the understanding of self-assembled structures as reaction nanoconfinements and establish a foundation for advanced material design.

Keywords: bicontinuous cubic structures; confined free radical polymerization; in situ GISAXS; self-assembly; thin films.