Synthesis, thiol-yne "click" photopolymerization, and physical properties of networks derived from novel multifunctional alkynes
MetadataShow full item record
Multifunctional alkynes (2, 3, or 4 ynes per monomer) were prepared utilizing the nucleophile-catalyzed thio-Michael addition reaction from commercially available multifunctional thiols (2, 3, or 4 thiols) and propargyl acrylate. Real-time FTIR (RTIR) and NMR spectroscopies indicate that the conjugate addition under these conditions proceeds to high conversions within seconds using the nucleophilic catalyst dimethylphenylphosphine, in the absence of solvent, at ambient temperature, and with no side products. A family of polymer networks was prepared by the photoinitiated thiol-yne reaction employing a 2:1 ratio of thiol to alkyne, which resulted in uniformly cross-linked materials of systematically increasing cross-link density. Photopolymerization kinetic profiles indicate that the thiol-yne reaction proceeded rapidly to high conversion with conversions decreasing with increasing functionality of the thiol and/or alkyne groups. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) results clearly indicate that the glass transition temperature increases as the overall cross-link density increases (from -10 to 42 °C by DMTA). An increase in the rubbery modulus (from 6 to 23 MPa at 70 °C) results as the functionality increases, with a concomitant decrease in the molecular weight between cross-links. © 2010 American Chemical Society.
Showing items related by title, author, creator and subject.
Lowe, Andrew; Hoyle, C.; Bowman, C. (2010)Radical mediated thiol-yne polymerization reactions complement the more well-known thiol-ene radical polymerization processes, with the added advantage of increased functionality. In one system studied, the rate constant ...
Formation and characteristics of glucose oligomers during the hydrolysis of cellulose in hot-compressed waterYu, Yun (2009)Energy production from fossil fuels results in significant carbon dioxide emission, which is a key contributor to global warming and the problems related to climate change. Biomass is recognized as an important part of ...
Chan, J.; Zhou, H.; Hoyle, C.; Lowe, Andrew (2009)A series of photoinitiated reactions involving radical chain addition of dithiols across the triple bonds of dialkynes results in quantitative loss of all of the thiol and alkyne groups in 1:1 molar functional group neat ...