Molecular Design of a Discrete Oligosaccharide-block-Oligodimethylsiloxane System: Toward Microphase Separation with 1 nm Domain Size and Angstrom-Scale Size Control

Abstract

Herein, we present a novel discrete block copolymer (BCP) system consisting of oligodimethylsiloxane and maltooligosaccharide in which the polymerization degrees of both blocks can be modulated at one-monomer resolution, allowing synthetic access to a discrete BCP with degree series of polymerization. The thiol-ene reaction of α,ω-diallyl-functionalized oligodimethylsiloxanes with thiol-functionalized maltooligosaccharides readily accessed the discrete BCPs. Small-angle X-ray scattering revealed microphase-separated lamellar structures with d of 3.59-4.99 nm depending on the degree of polymerization, among the smallest ever reported in sugar-based BCPs. Moreover, the d-value was precisely controlled on the scales of 0.4-0.5 Å and 0.59-0.85 nm by increasing or decreasing the monomeric glucose and dimethylsiloxane units, respectively. In addition, we discovered that the degree of polymerization, linker structure, and molecular weight distribution significantly impact the dimensions and structural stability of the BCPs.