Preparation and mechanism of free‐radical/cationic hybrid photosensitive resin with high tensile strength for three‐dimensional printing applications

Abstract

A ultraviolet (UV)-curing free-radical/cationic hybrid resin is designed and developed by blending epoxy resin with an acrylic resin, including N-acryloyl morpholine, polyurethane acrylic ester (PUA), free-radical and cationic photoinitiator. During UV-curing, crosslinking locks the acrylate and epoxide polymers together through non-covalent interaction. Most likely, the interpenetrating polymer network (IPN) structure can be generated in the threedimensional (3D)-printed objects. The obtained results from Fourier transform infrared spectroscopy (FT-IR) show that bisphenol A epoxy resin and acrylic resin are both successfully involved in the UV-curing process. In addition, the effects of the mass ratio of epoxy to acrylic resin and the UV irradiation time on the properties of the hybrid resin are systematically investigated using liquid crystal display (LCD) 3D printers. It is found that the tensile strength of the hybrid resin increases in a certain range and the elongation at the break maintains an upward trend with the increasing mass ratio. Finally, it is found that the shrinkage of the hybrid resin also depends on the mass ratio of epoxy to acrylic resin, which decreases with the increase of the epoxy resin content in a certain range. Thus, herein we propose a feasible UV-curing mechanism for the synthesis of hybrid resins for 3D printing applications.

Synthesis and Optimization of a Free-Radical/Cationic Hybrid Photosensitive UV Curable Resin Using Polyurethane Acrylate and Graphene Oxide

“…This system can effectively overcome the difficulty of curing a single system by integrating the advantages of the two systems, compensate for the individual defects in performance, and achieve the effect of 1 + 1 > 2. In addition, interpenetrating network structures (IPNs) [ 19 , 20 ] may be formed during hybrid light curing, leading to inclusion and synergy, which improves the curing speed, weakens the influence of oxygen polymerization inhibition, and significantly reduces the shrinkage, Therefore, scholars are increasingly beginning to study hybrid photosensitive resins to combine the rapid curing rate of free radical photopolymerization and the good mechanical properties obtained by cationic polymerization [ 21 , 22 , 23 ].…”

“…IPNs consist of two or more chemically crosslinked permeable polymer networks and can be formed by polymerizing a mixture of multi-functional monomers in different ways [ 19 , 20 , 21 , 22 , 23 , 24 ]. Free radical polymerization is typically used to form acrylic resins [ 25 ], including epoxy acrylic resin [ 26 ], polyurethane acrylic resin [ 27 ], and polyester acrylic resin.…”

“…Guanghong [ 31 ] et al prepared a free radical/cationic hybrid photosensitive resin using a mixture of epoxy resin (epon828) and polyurethane acrylate (rj429), which exhibited a tensile strength of 6.60 MPa and a volume shrinkage and warpage of 3.986% and 3.62%, respectively. Zijun [ 19 ] blended an epoxy resin, acrylic resin, free radical, and cationic photoinitiator to obtain an IPN epoxy composite with a complex 3D structure and excellent toughness and ductility. Ting [ 32 ] et al synthesized a hybrid system containing an epoxy acrylic acid, epoxy resin, and a photoinitiator, to which modified calcium sulfate whisker (CSW) was added as an inorganic filler.…”

Preparation of Bis[(3-ethyl-3-methoxyoxetane)propyl]diphenylsilane and Investigation of Its Cationic UV-Curing Material Properties

“…With the rapid development of UV-curing technology, cationic UV-curing systems are attracting increased attention because of their outstanding advantages. Cycloaliphatic epoxides, oxetanes and bisphenol A type epoxy compound are used as prepolymers in the cationic curing systems [ 29 , 30 ]. Compared to the cycloaliphatic epoxides of cationic UV-curing systems, oxetane polymerization have a lower viscosity, lower toxicity, higher curing rate and higher thermal stability [ 30 , 31 ].…”

“…Cycloaliphatic epoxides, oxetanes and bisphenol A type epoxy compound are used as prepolymers in the cationic curing systems [ 29 , 30 ]. Compared to the cycloaliphatic epoxides of cationic UV-curing systems, oxetane polymerization have a lower viscosity, lower toxicity, higher curing rate and higher thermal stability [ 30 , 31 ]. However, the photosensitivity of oxetanes is worse than the cycloaliphatic epoxides, which limits its scope of application for oxetanes [ 32 , 33 , 34 , 35 ].…”