Influence of actinic wavelength on properties of light-cured interpenetrating polymer networks

Abstract

Interpenetrating polymer networks (IPNs) composed of different acrylate/epoxide ratios, were synthesized under UV and visible‐LED curing conditions. The formation of the IPNs was explored in terms of phase separation, polymerization mechanisms, final mechanical properties and surface morphology. For these purpose, we uniquely combined results of miscibility investigations, confocal Raman microscopy, dynamical mechanical analysis and atomic force microscopy. Transparent films were obtained for all compositions and both irradiation sources. The thermo‐mechanical properties of different IPNs were associated to the presence of acrylate‐ or epoxide‐rich phases, as well as, mixed interphases, resulting from the high interpenetration between both networks. Although the final conversions were similar under UV and visible‐LED irradiation, we have found evidence that the visible‐cured samples provide higher IPN homogeneity and lower Tg, for a higher epoxide content. To explain this trend, the mechanisms and sequence of the acrylate or epoxide networks formation, under UV or LED irradiation, is discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1378‐1390

Kinetically Controlled Photoinduced Phase Separation for Hybrid Radical/Cationic Systems

“…Photopolymerization-induced phase separation (PhIPS) is one promising technique to generate polymer morphologies with multiple domains and controllable properties. − PhIPS offers direct control over polymerization kinetics, which directly impacts polymer network formation and phase separation through irradiation conditions, photoinitiator type/concentration, and formulation. With this approach, phase separation is developed during the polymerization of an initially homogeneous hybrid radical/cationic formulation.…”

LED-cured self-replenishing hydrophobic coatings based on interpenetrating polymer networks (IPNs)

“…Nowadays, this technique has already been applied to produce IPNs. [9][10][11][12][13][14][15][16][17][18][19] The main benet of applying a photo-curing process to produce IPNs is that the fast cross-linking reaction could kinetically impede macro-scale phase separation between the individual networks in the IPNs so that the nal properties can be improved by a more controlled meso-morphology. Moreover, different polymerization mechanisms can be carried out simultaneously but independently from each other, which allow a more exible selection of the desired chemical systems in order to tune the properties.…”

“…3,11,13,17,18 In recent years, visible light sources such as LEDs are also becoming appealing, particularly for industrial applications, to carry out the photo-curing of coatings, due to their special characteristics such as long life-time, low heat generation and higher energy savings. 17,[20][21][22] Considering all these features, LED photo-cured IPNs can become a very attractive choice for the coatings eld.…”

“…For instance, photo-cured IPNs based on acrylate/ methacrylate and epoxide combinations have gained particular attention since both radical and cationic polymerization mechanisms can be carried out simultaneously. 3,11,13,17,18 In recent years, visible light sources such as LEDs are also becoming appealing, particularly for industrial applications, to carry out the photo-curing of coatings, due to their special characteristics such as long life-time, low heat generation and higher energy savings. 17,[20][21][22] Considering all these features, LED photo-cured IPNs can become a very attractive choice for the coatings eld.…”

“…The photoinitiating system, which has been reported previously 17 is composed of ITX, Irgacure 250 and BA and was added to the formulation. The uorinated dangling chains (DCs) with a poly(caprolactone) spacer were introduced at a constant amount in the IPNs for bringing the selfreplenishing effect.…”