Rubbery wound closure adhesives. I. design, synthesis, characterization, and testing of polyisobutylene-based cyanoacrylate homo- and co-networks

Novel rubbery wound closures containing various proportions and molecular weights of polyisobutylene (PIB) and poly(2-octyl cyanoacrylate) [P(OctCA)] for potential clinical use were designed, synthesized, characterized, and tested. Homo-networks were prepared by crosslinking 3-arm star-shaped PIBs fitted with terminal cyanoacrylate groups, [Ø(PIB-CA)3], and co-networks by copolymerizing Ø(PIB-CA)3 with OctCA using N-dimethyl-p-toluidine (DMT). Neat Ø(PIB-CA)3, and Ø(PIB-CA)3/OctCA blends, upon contact with initiator, polymerize within seconds to optically transparent strong rubbery co-networks, Ø(PIB-CA)3-co-P(OctCA). Homo- and co-network formation was demonstrated by sol/gel studies, and structures and properties were characterized by a battery of techniques. The Tg of P(OctCA) is 58 °C by DSC, and 75 °C by DMTA. Co-networks comprising 25% Ø(PIB-CA)3 (Mn  = 2400 g/mol) and 75% P(OctCA) are stronger and more extensible than skin. Short and long term creep studies show co-networks exhibit high dimensional stability and \u3c6% creep strain at high loading. When deposited on porcine skin co-networks yield hermetically-adhering clear rubbery coatings. Strips of porcine skin coated with co-networks could be stretched and twisted without compromising membrane integrity. The co-network is nontoxic to L-929 mouse fibroblasts

Multi-methacrylated star-shaped, photocurable poly(methyl methacrylate) macromonomers via quasiliving ATRP with suppressed curing shrinkage

Novel, star-shaped multifunctional poly(methyl methacrylate) (PMMA) macromonomers with well-defined average number of pendant methacrylate groups were synthesized by copolymerizing MMA with 2-hydroxyethyl methacrylate (HEMA) via quasiliving ATRP with a tetrafunctional initiator in methanol at 10 °C, followed by methacrylation of the hydroxyl groups of the HEMA units. The resulting tailor-made poly(methyl methacrylate-co-2- methacryloylethyl methacrylate), P(MMA-co-MEMA), multifunctional macromonomers were used as cross-linking agents in photocuring of MMA, a solvent for its own polymer, and thus chemically homogeneous PMMA networks were formed in which the tetrafunctional initiator moiety provides inherent, additional branching points in the resulting cross-linked materials. This approach, even in the presence of relatively low amounts of macromonomers of ∼35–45%, provides sol-free products and up to ∼40% less polymerization shrinkage than that by curing of MMA with a conventional low molecular weight bifunctional methacrylate. These new, unique star-shaped PMMA macromonomers are potential cross-linkers in a variety of solvent-free applications where low curing shrinkage and high conversions are critical requirements, such as in several engineering materials, coatings, dental fillings and restorations, bone cements etc