Crosslinking polymerization leading to interpenetrating polymer network formation. I. Polyaddition crosslinking reactions of poly(methyl methacrylate‐co‐2‐methacryloyloxyethyl isocyanate)s with ethylene glycol resulting in polyurethane networks

Abstract

At the start of our research program concerned with the elucidation of the crosslinking polymerization mechanism leading to interpenetrating polymer network (IPN) formation, in which IPNs consist of both polymethacrylates and polyurethane (PU) networks, this article deals with the polyaddition crosslinking reaction leading to PU network formation. Therefore, 2-methacryloyloxyethyl isocyanate (MOI) was radically copolymerized with methyl methacrylate (MMA) in the presence of CBr 4 as a chain-transfer agent. The resulting poly(MMA-co-MOI)s, having pendant isocyanate (NCO) groups as novel multifunctional polyisocyanates, were used for polyaddition crosslinking reactions with ethylene glycol as a typical diol. The second-order rate constants depended on both the functionality of poly(MMA-co-MOI) and the NCO group concentration. The actual gel points were compared with the theoretical ones calculated according to Macosko's equation; the deviation of the actual gel point from the theoretical value became more remarkable for a greater functionality of poly(MMA-co-MOI) and at a lower NCO group concentration or at a lower poly(MMA-co-MOI) concentration. These are discussed mechanistically, with consideration given to the significance of intramolecular cyclization and intramolecular crosslinking reactions leading to the shrinkage of the molecular size of the prepolymer, along with the data of the intrinsic viscosities of resulting prepolymers and the swelling ratios of resulting gels.

Inter‐ and Intramolecular Crosslinking Kinetics: Partitioning According to Number of Crosslinks

“…Intramolecular crosslinking reactions occur between two functional groups on the same polymer [1][2][3] or polypeptide, [4,5] causing connective loops within the macromolecule. The functional groups that participate in crosslinking are pendant unsaturated bonds, [3] cationic groups, [1,6] or other moieties that can react with each other.…”

Crosslinking polymerization leading to interpenetrating polymer network formation. 3. Polyaddition crosslinking reaction of poly(methyl methacrylate‐co‐2‐methacryloyloxyethyl isocyanate) with poly(oxytetramethylene) glycol in the presence of linear polymethacrylate resulting in semi‐interpenetrating polymer network

“…Our research program for clarifying the IPN formation mechanism is a successive understanding of (1) the polyaddition crosslinking reaction leading to PU network formation, (2) the reaction mechanism forming semi‐IPNs consisting of PU networks and linear or branched PMs, and (3) the reaction mechanism forming sequential or simultaneous IPNs consisting of both PU and PM networks. In our previous articles,66, 67 we discussed in detail the polyaddition crosslinking reactions leading to PU network formation. Thus, the equimolar polyaddition crosslinking reactions of poly(methyl methacrylate‐co‐2‐methcryloyloxyethyl isocyanate)s (poly(MMA‐ co ‐MOI)s), having pendant isocyanate (NCO) groups as novel multifunctional polyisocyanates, with ethylene glycol (EG),66 1,6‐hexane diol (HD),67 and 1,10‐decane diol (DD)67 were explored in detail.…”

Construction of Crosslink‐System‐Materials Utilizing Designed Network‐Polymer‐Precursor Modules

“…Thus, we could construct novel CSMs utilizing designed NPPs as modules, providing semi-interpenetrating polymer network (IPN) involving DAT networks and linear poly(BzMA), [46] and simultaneous-IPN between polymethacrylate and polyurethane networks, [47][48][49] novel amphiphilic CSMs [37][38][39]50,51] and patchwork-type CSMs, [52] and so on. Another example is concerned with the emulsion crosslinking (co)polymerization of multivinyl monomers, [53] especially focusing on the formation of reactive crosslinked polymer nanoparticles (CPNs) as models of microgels, with the intention of clarifying the correlation of the network structure with the reactivity of resulting CPNs which would be useful as functionalized polymeric materials.…”