Kinetics of photocrosslinking reactions of a DCPA/EA matrix in the presence of thiols and acrylates

Abstract

The crosslinking efficiency and kinetics of a solid acrylic copolymer DCPA/EA (dicyclopentenyl acrylate/ethyl acrylate) matrix were investigated in the presence of pentaerythritol tetrakis (2‐mercaptoacetate) (PETMP) or pentaerythritol tri‐ and tetraacrylates used as multifunctional crosslinking agents. The reaction of thiol and acrylate addition was sensitized by benzophenone (BP). The crosslinking efficiency of the DCPA/EA—BP—PETMP copolymer system, illuminated at high wavelengths (λ > 310 nm), was compared with that of the DCPA/EA matrix alone and the 2‐component system copolymer DCPA/EA–BP. The concentrations of photosensitizer and crosslinking agent were varied from 1 to 10 mass %. The kinetics of tetrafunctional thiol addition and cyclopentene (pendant group of the DCPA/EA matrix) disappearance was followed through Fourier transform infrared (FTIR) and by determining the gel content. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2333–2345, 1997

Influence of Type of Initiation on Thiol–Ene “Click” Chemistry

“…[58] Thiol-ene reactions can be induced photochemically or thermally at ambient temperature in the presence of oxygen without undesirable side reactions such as sulfenyl radical coupling. [59][60][61][62] Importantly, these reactions can be considered as environmentally friendly processes since they precede in the absence of solvent under benign reaction conditions without the use of any potentially toxic metal. Recently, Hawker and co-workers investigated and compared the efficiency and orthogonality of thermally and photochemically initiated thiol-ene click coupling reactions.…”

Photopolymerization Reactions: On the Way to a Green and Sustainable Chemistry

“…For example, the development of sunlight photosensitive formulations (see, e.g., [77][78][79][80][81][82][83][84][85] and references therein; see also the patent literature aiming at industrial applications) for the drying of paints for crack-bridging applications, anti-soiling properties, the manufacture of interpenetrating polymer networks (IPN) usable as protective coatings and glues, the fabrication of glass fiber reinforced composites, hard and rigidified four layer glass cloth laminate, clearcoats and polymer-clay composites has been realized in the past, but these systems, except some of them (e.g., those described in [79,80,84]) suffer from oxygen inhibition and a relatively low photosensitivity.…”

Cure Depth of Photo‐Polymerized Gels

“…By identifying I with [I], one can obtain logarithm of M 0 /M at t ! 1 from Equation (2), (13), and (10) as:…”

“…Initiators also play an important role to control the reactivity of the system. As well as the classical phenylketones, which undergo Norrish‐I type cleavage, thiols are also employed . In some cases, photosensitizers are added to catalyze the initiation reactions .…”

“…As well as the classical phenylketones, which undergo Norrish-I type cleavage, thiols are also employed. [12,13] In some cases, photosensitizers are added to catalyze the initiation reactions. [14] The rate of reaction in the curing process grossly depends on intensity of light, length of samples, concentration of initiators, and gelling agents.…”