Synthesis and Characterization of Glycomethacrylate Hybrid Stars from Silsesquioxane Nanoparticles

Abstract

A silsesquioxane nanoparticle based macroinitiator of ca. 58 functions was synthesized and characterized using 1H NMR, MALDI-TOF MS, and elemental analysis. The macroinitiator was used to synthesize glycomethacrylate stars with approximately 25 arms of different lengths using 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (MAIGlc) as the monomer via atom transfer radical polymerization (ATRP). Well-defined glycostars could be synthesized by restricting the polymerization to low conversion. The molecular weights of the star polymers were determined using gel permeation chromatography (GPC) with viscosity and multiangle light scattering (MALS) detectors. To determine the efficiency of the initiating sites, the arms were cleaved from the core by solvolysis with sodium methoxide and thoroughly characterized, indicating that ca. 25 arms per star had been synthesized. The morphology of the glycostars was visualized using scanning force microscopy (SFM) and field emission scanning electron microscopy (FE-SEM). Deprotection of the isopropylidene groups resulted in water-soluble stars that were characterized using SFM, SEM, asymmetric flow field-flow fractionation (AF-FFF), dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and bright-field transmission electron microscopy (TEM).