“Grafting Through”: Mechanistic Aspects of Radical Polymerization Reactions with Surface-Attached Monomers

Abstract

In this paper, we investigate the influence of selected reaction parameters on the formation of surface-attached polymer monolayers. The process is based on the use of self-assembled monolayers containing a polymerizable group and the performance of a bulk free radical polymerization reaction (“grafting through polymerization”). To this, methacryl moieties were immobilized on silica gel surfaces via a silane linker. During the polymerization reaction in a conventional way, free polymer is formed in solution. However, every now and then during chain growth also surface-attached monomers become integrated in the polymer chains, leading instantaneously to covalent linking of the growing polymer molecules to the surfaces. As more and more polymer chains become attached, this leads to the formation of a surface-attached polymer layer on the silica surface. Various sets of polymerization reactions were performed and the influence of a variation of temperature, reaction time and concentration of monomer, initiator, and immobilized monomer onto the layer formation are investigated. We propose a model of the layer formation process and the grafting-through process is compared to grafting-to and grafting-from techniques.

Antifouling and antibacterial hydrogel coatings with self-healing properties based on a dynamic disulfide exchange reaction

“…3- 15 Mercaptopropyl trimethoxysilane (MTS, 95%), poly(ethylene glycol)methyl ether methacrylate (PEGMA, n~9, average molecular weight M n~5 00), N-hydroxyethyl acrylamide (HEAA, 97%), 2-(methacryloyloxy)ethyl trimethylammonium chloride solution (META, 80 wt% in H 2 O), bis(2-methacryloyl)oxyethyl 20 disulfide (BMOD) and fluorescein isothiocynate-conjugated bovine serum albumin (BSA-FITC) were purchased from Sigma-Aldrich Co., St. Louis, MO. HEAA and PEGMA were passed through an inhibitor-removal column (Sigma-Aldrich) and then stored under an argon atmosphere at 4°C.…”

“…The 10 gel fractions (GF) were calculated as follows: GF=W d /W i , where W d is the weight of the dried insoluble part of sample after extraction with ethanol and water, while W i is the initial dry hydrogel. The equilibrium water swelling ratios (ESR) were calculated as follows: ESR=(W s ̶ W d )/W d , where W d and W s 15 represent the weights of dry and equilibrium swollen hydrogels.…”

“…1b), including S (2s: 228 eV, 2p: 164 eV) and Si (2s: 151 eV, 2p: 99 eV) XPS peaks. 32,33 The appearance of these signals indicates the successful introduction of thiol groups on the SS surfaces for the subsequent 15 surface-initiated thiol-ene photopolymerization.…”

“…The other strategy is based on reversible bonding systems. 6,[15][16][17][18] They are able to heal repeatedly, arising from the dynamic covalent or non-covalent interactions. Various covalent and non-covalent bonds have been explored for construction of reversible self-healing materials.…”

Surface-initiated controlled radical polymerizations from silica nanoparticles, gold nanocrystals, and bionanoparticles

“…Sooner or later, the pre-attached polymerizable moiety will be integrated into the growing polymer chains. 39 The much more applied grafting-from method has become increasingly popular in recent years. Functional initiators are chemically linked onto the nanoparticle surface to initiate the polymerization directly, which is called surface-initiated polymerization.…”