The Green Functionalization and Crosslinking of Polyisobutylenes for Bioadhesive Employment
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Two of the most commonly employed bioadhesives used for wound closure applications today are fibrin-based and cyanoacrylate-based bioadhesives, both of which have adverse effects. Fibrin-based bioadhesives allow for the possible transmission of viral blood-borne pathogens, while cyanoacrylate-based bioadhesives have toxicity concerns due to their degradation into formaldehyde. To address these drawbacks and many others, it is proposed that a polyisobutylene-based bioadhesive be employed, since polyisobutylene has a long, successful history as a bio-friendly material.
Potential polyisobutylene-based bioadhesives first were prepared by the difunctionalization of α-ω-dihydroxy polyisobutylenes with vinyl methacrylate through “green” enzyme catalyzed Candida antarctica lipase B (CALB) transesterification reactions at 50℃ within 24 hours with high yields.
Four different compounded crosslinking solution formulations consisting of synthesized α-ω-dimethacrylate polyisobutylenes, 10% or 20% of the trifunctional crosslinker 2-ethyl-2-hydroxymethyl-1-,3-propanediol trimethacrylate (TMP-TMA) and a 20% solution of the ultra-violet (UV) reactive photoinitiator 2,2-dimethoxy-2-phenylacetophenone effectively demonstrated the ability to crosslink terminally functionalized linear polyisobutylenes into continuous film networks under ambient conditions quickly (< 5 min.) by the use of UV light.
Various techniques were used to characterize their crosslinking and physical properties, as well as to determine that the molecular weight of α-ω-dimethacrylate polyisobutylenes had a greater effect on the characterizable attributes than the amount of TMP-TMA employed. Techniques used to characterize the continuous polyisobutylene film networks included: the evaluation of polyisobutylene film discontinuities; the measurement and calculation of their physical dimensions; aesthetic evaluation; solvent extraction and swelling assessments; FTIR; TGA; and DSC. These methods characterized the produced polyisobutylene film networks as being continuous with a glossy, translucent, uniform light yellow-tinted appearance; highly crosslinked; hydrophobic in nature; and as having low extractables.
Other potential polyisobutylene-based bioadhesives also were prepared by the difunctionalization of α-ω-dihydroxy and α-ω-diamino polyisobutylenes with divinyl adipate, vinyl acrylate or crotonic acid vinyl ester through “green” enzyme catalyzed CALB transesterification and Michael addition reactions. α-ω-Divinyl and α-ω-dicrotonate polyisobutylenes of various molecular weights were synthesized at 50℃ within 24 hours with high yields. 11-Mercaptoundecyl vinyl adipate, the first product of a two-step reaction pathway to synthesize α-ω-dithiol polyisobutylene, also was produced, but required 48 hours of reaction and provided moderate yields.
Characterization by proton 1H and 13C NMR, SEC and MALDI-ToF MS determined that the resulting synthesized difunctionalized polyisobutylenes had high purity, expected molecular weights, uniform polydispersities, and had either (meth)acrylate- or vinyl ester-end group difunctionalized structures that are ideal for crosslinking.
Document number: akron1353178867
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=akron1353178867
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