Effect of Copolymer on the Wrinkle Structure Formation and Gloss of a Phase-Separated Ternary Free-Radical/Cationic Hybrid System for the Application of Self-Matting Coatings

Abstract

Hybrid free-radical/cationic systems can generate phase-separated polymers or interpenetrating networks driven by photopolymerization. In this study, phase separation of a ternary mixture composed of a polybutadiene urethane diacrylate (PBUDA), a cycloaliphatic diepoxyde (CE), and hexanediol dimethacrylate (HDDMA) was investigated. Using systematic variations of the initial composition of the mixture, a miscibility phase diagram of the ternary mixture was established. Based on this diagram, a reactive copolymer (poly(butyl acrylate-co-glycidyl methacrylate) (PBGMA)) was introduced in a reference hybrid system to manipulate the crosslinking network, polymer morphology, and properties (e.g., roughness, gloss, strain at break, and glass transition temperature Tg). When cured as a coating, the ternary hybrid system showed a depthwise gradient of epoxy conversion, and thereby developed a mostly cured skin above a viscous sublayer of uncured monomer. This skin can develop compressive stress due to the swelling from the diffusion of unreacted monomers beneath, and if the compressive stress is significantly high, wrinkles appear on the coating’s surface. This work highlights how both skin thickness and elastic modulus impact wrinkle frequency and amplitude. It was demonstrated that these wrinkle parameters can be manipulated in the ternary system by the addition of PBGMA. We also demonstrated that by employing UV irradiation and varying the PBGMA content, it is possible to engineer coatings that range from smooth surfaces with high gloss to wrinkled topographies with a very low associated gloss.

Preparation of a self-matting, anti-fingerprint and skin-tactile wood coating via biomimetic self-wrinkling patterns

“…Owing to their unique surface structures, wrinkled surfaces typically exhibit excellent light reflectivity, wettability, and adhesion. Consequently, artificial surfaces with biomimetic wrinkled structures are being extensively applied in fields like optics, self-cleaning coatings, and flexible electronics 6 – 10 , and it has become important to develop a simple and efficient method for fabricating self-wrinkling coatings.…”

A novel self-wrinkled polyurethane-acrylate wood coating with self-matting, anti-fingerprint performance and skin-tactile feeling via excimer lamp/UV curing

“…Surface wrinkles not only improve the performance of coating, but also give coating more special functions and wider application potential. Calvez et al (2022) studied the phase separation of a ternary mixture (PBGMA) consisting of polybutadiene polybutadiene diacrylate (PBUDA), cycloaliphatic diepoxide (CE) and hexadiol dimethacrylate (HDDMA). 31 The mixture is separated by a ternary phase and subjected to UV curing to form a matting coating with a self-wrinkled surface.…”

“…Calvez et al (2022) studied the phase separation of a ternary mixture (PBGMA) consisting of polybutadiene polybutadiene diacrylate (PBUDA), cycloaliphatic diepoxide (CE) and hexadiol dimethacrylate (HDDMA). 31 The mixture is separated by a ternary phase and subjected to UV curing to form a matting coating with a self-wrinkled surface. Similarly, Zhang et al (2022) prepared a gloss controlled UVcurable matting self-wrinkled waterborne urethane acrylate coating by controlling the number and depth of folds by adjusting the amount of photoinitiator added.…”

Effect of Photoinitiator Concentration and Film Thickness on the Properties of UV-Curable Self-Matting Coating for Wood-Based Panels

“…Matte coating is a type of surface decoration coating that has been extensively used in leather finishing [6], vehicle interior topcoats [7], paper [8], textiles [9], and wood finishing [10]. Typically, three strategies are employed for preparing matte coatings, including adding matting agents to the coatings, developing self-matting resins or phaseseparated hybrid systems [11,12], and the physical extinction of the coating surface by different curing techniques and equipment (such as electron beam curing and vacuum UV curing), with the ultimate goal of achieving a rough surface and low gloss [13,14]. In the previous study, we found that the third method mainly utilizes the instability of the coating film during the curing process, resulting in wrinkles on the surface of the coating film [15].…”