High Refractive Index Monomers for Improving the Holographic Recording Performance of Two-Stage Photopolymers

Abstract

Photopolymers hold great promise for the preparation of transparent volume holographic gratings (VHG), which are core optical elements in many application fields. To improve the holographic recording property of a two-stage photopolymer, four new (meth)acrylate monomers (CTA, CTMA, CTBA, CTBMA) with high refractive indices (1.59−1.63) are designed and synthesized in this study. Using them as one writing monomer, a series of photopolymer samples with different formulations and thicknesses are fabricated for holographic recording. Among them, a formulation containing 9 wt % CTMA shows the best performance. Using it as a recording medium, a VHG with high resolution and diffraction efficiency is constructed. Its refractive index modulation reaches 0.046. Moreover, its total transmittance within 400−800 nm achieves 96.62% after photobleaching. The results indicate that the CTMA-based formulation has great application potential in developing highperformance transparent VHG.

Stimulus-responsive polymer materials toward multi-mode and multi-level information anti-counterfeiting: recent advances and future challenges

“…). Furthermore, converting the observation of the optical path, 43,44 constructing a certain orientation structure of materials to obtain polarization patterns, 45–47 and utilizing holographic photopolymerization to obtain holographic images 48–53 are also effective means to realize physical color-based changes in SRPs. (ii) Shape memory SRPs.…”

High-Performance Holographic Photopolymers Based on Low Refractive Index Host Matrices Containing Fluoroelastomers

“…Holographic optical elements (HOEs) have been widely used in near-eye display systems such as virtual reality, augmented reality (AR), mixed reality, and head-up display fields due to their advantages of lightweight, small size, convenient production, easy miniaturization, and functional integration. , Photopolymers possess great application potential in fabricating transparent HOEs, so they have gained widespread attention in recent years. − The refractive index modulation (Δ n ) of photopolymers is a key indicator to determine their holographic performance. ,− Though there are a few photopolymers with Δ n above 0.05, their preparation processes require the use of volatile solvents, which is not favorable for large-scale applications. , So far, with the exception of BayerHX, almost no solvent-free photopolymers with Δ n above 0.05 have been reported . Therefore, the development of solvent-free photopolymers capable of Δ n as high as possible is becoming a hot research topic in this field. ,,, …”

“…Photopolymers for holographic recording consist of three main components: photoinitiating system, host matrix, and writing monomer. ,, The host matrix (also known as a binder or film-forming resin) plays a role in shaping and supporting to provide mechanical stability for the photopolymer. , During holographic exposure, the monomers in bright fringes undergo polymerization first. Then, a concentration gradient is generated between the bright and dark fringes, which drives the monomers in the dark fringes to migrate to the bright fringes. , Meanwhile, the host matrix in the bright fringes is squeezed into dark fringes . Finally, a refractive index modulated volume holographic grating (VHG) will be formed.…”

Adaptable Networks with Semiorthogonal Two-Stage Polymerizations Enabled by Sequential Photoinitiated Thiol–Ene and Disulfide–Ene Reactions

“…17,18 Beyond mechanical property programming, spatial patterning of the refractive index is often utilized in two-stage systems for applications such as holographic gratings. 19 However, in these applications, two-stage polymer formulations suffer from several limitations, including phase separation and unwanted diffusion of mobile species during the reaction, leading to haze and limited transparency in optical materials and diminishing the fidelity of patterning or shape programming. 20−23 To mitigate the aforementioned challenges, the formation of covalent bonds between the monomer components involved in both curing steps has proven to be extremely valuable for improving the fidelity of second-stage photopolymerizations.…”

“…Shape fixation in two-stage materials is usually achieved in second-stage polymerization when deformations in the first-stage network are stabilized mechanically . Similarly, two-stage photopolymers offer unique advantages for lithography, for example, nanoimprint lithography, in which resists require differing material properties in the imprinting step (soft enough to deform) and the final material properties (stiff and durable). , Beyond mechanical property programming, spatial patterning of the refractive index is often utilized in two-stage systems for applications such as holographic gratings . However, in these applications, two-stage polymer formulations suffer from several limitations, including phase separation and unwanted diffusion of mobile species during the reaction, leading to haze and limited transparency in optical materials and diminishing the fidelity of patterning or shape programming. − …”