Dispersion of Gold Nanoparticles in UV-Cured,Thiol-Ene Films by Precomplexation of Gold-Thiol

摘要

Alkyl thiols and alkenes(enes) polymerize via an extremely rapid step-growth,free-radical chain process,uninhibited by air,to give high-density networks with excellent mechanical and physical properties.These thiol-ene coatings are potentially useful for a wide variety of coatings,adhesives,and optical applications.In this work,a series of nanogold-containing UV-cured,thiol-ene coatings were prepared from trimethylolpropane tris(3-mercaptopropionate)(trithiol) and pentaerythritol allyl ether(triene) monomers using a unique procedure which facilitates precomplexation of the gold-thiol prior to photocuring.Irgacure 651(1 wt%) was used as a photoinitiator,and nanogold was incorporated at 0-1 wt%,average ~10 nm size particles by TEM.Physical and mechanical properties were characterized using bulk tack analysis and other standard techniques:DSC,TGA,pencil hardness,and gel fractions.In general,films were found to be low absorbing in the visible range and highly uniform and to contain well-dispersed nanogold particles.Although the rate of polymerization was modestly retarded by the presence of gold nanoparticles,functional group conversions(C=C and S-H) and gel fractions were high.Increasing nanogold content resulted in an increase in T_g measured by DSC(-15 to-8°C for 0-1 wt% nanogold,respectively) due to the increasing number of physical gold-thiol cross-links created.TGA analysis revealed a small negative impact of increasing nanogold composition on relative thermal stability.The 1 wt% nanogold-containing samples possessed appreciable electrostatic discharge(ESD) character,with ESD times of 1-10 s measured using a commercial charge plate analyzer.