Facile Access to Hydroxy‐Functional Core–Shell Microspheres via Grafting of Ethylene Oxide by Anionic Ring‐Opening Polymerization

Abstract

We present a facile access route to hydroxy-functional narrow disperse microspheres of well-defined grafting density (GD). Ethylene oxide has been grafted from highly crosslinked poly(divinyl benzene) microspheres by anionic ring-opening polymerization using sec-butyllithium as activator together with the phosphazene base t-BuP(4) . Initially, core microspheres have been prepared by precipitation polymerization utilizing divinyl benzene (DVB, 80 wt.-%). The grafting of poly(ethylene oxide) (PEO) from the surface resulted in the formation of functional core-shell microspheres with hydroxy-terminal end groups. The number average particle diameter of the grafted microspheres was 3.6 µm and the particle weight increased by 5.7%. The microspheres were characterized by SEM, FT-IR spectroscopy, elemental analysis, and fluorescence microscopy. The surface GD (determined via two methods) was 1.65 ± 0.06 and 2.09 ± 0.08 chains · nm(-2) , respectively.

Quantification of Grafting Densities Achieved via Modular “Grafting‐to” Approaches onto Divinylbenzene Microspheres

“…The volume of one microsphere is 1.2 mm 3 , and the density of the core microsphere is 1.18 g cm À3 . [38] Therefore, one microsphere weighs 1.42 Â 10 À12 g, which corresponds to 0.70 Â 10 12 core microspheres per gram of material. One microsphere has a particle SA of 5.47 Â 10 6 nm 2 .…”

“…The actual grafting densities obtained in this case (0.3 chains nm À2 ) are similar to the graft densities obtained on silicon surfaces via RAFT polymerization. [37] Barner and Müller [38] recently reported the functionalization of DVB80 microspheres with poly(ethylene glycol) chains using a grafting-from approach via anionic polymerization techniques. These resulting poly(divinylbenzene)-graft-poly(ethylene oxide) (PDVB-g-PEO) microspheres exhibit a nominal surface grafting density of 1.65-2.09 chains nm À2 .…”

Surface Modification of Spherical Particles with Bioactive Glycopolymers

“…Bovine by Ciampolini et al 37 The synthesis of 2-[p-(2-hydroxy-2-methylpropiophenone)]-ethyleneglycol methacrylate (HMEM) has been described previously. 38 The sugar-based functional monomer MAGlc was synthesized by deprotection of 3-O-methacryloyl-1,2:…”

“…The latter include reversible addition-fragmentation chain transfer polymerization (RAFT), [21][22][23][24][25][26][27][28][29] atom transfer radical polymerization (ATRP) [30][31][32][33][34][35] and nitroxide mediated polymerization (NMP). [36][37][38][39][40] Applying these techniques, a plethora of linear glycopolymers bearing various carbohydrate moieties were synthesized and analyzed. Linear glycohomopolymers show an interesting behavior in matters of bioactivity and biorecognition towards proteins, but their use for applications regarding biosensors or drug delivery is often limited.…”

“…30 The remaining double bonds enable the attachment of polymer chains to the surface via various grafting techniques. [31][32][33][34][35][36][37] The "grafting through" approach in this study led to microspheres covered with linear or hyperbranched glycopolymers via ATRP and SCVCP, respectively. In this approach hyperbranched polymers first grow in solution, then add to the PDVB vinyl groups, and grow further in a grafting onto -grafting from fashion.…”