Effects of chain-transferring thiol functionalities on the performance of nanoparticle-polymer composite volume gratings

Abstract

We report influences of varying functionalities of thiols as chain transfer agents on the spatial frequency response, polymerization shrinkage, and thermal stability of a volume grating recorded in a photopolymerizable ZrO₂ nanoparticle-polymer composite film. It is shown that a substantial increase in the saturated refractive index modulation is realized at high spatial frequencies by doping with multifunctional thiols. Moreover, the incorporation of multifunctional thiols considerably suppresses polymerization shrinkage of recorded volume gratings and thermal changes in refractive index and film thickness as compared with the case of mono-thiol. These results indicate that multifunctional thiols provide effective control of the properties of nanoparticle-polymer composite volume gratings for various applications in light and neutron optics.

Photopolymerizable nanocomposite photonic materials and their holographic applications in light and neutron optics

“…However, in order to explain various experimental observations (e.g. a strong grating-spacing dependence on [ 35 , 41 , 47 , 71 , 72 , 74 , 76 ]) and to make the material optimization possible for specific applications, one needs to establish a more appropriate statistical thermodynamic model that accurately takes the interaction of nanoparticles with monomer and the formed polymer [ 119 ] into account.…”

“…However, the reduced shrinkage of volume gratings recorded in MA-based NPCs was still of the order of 1%, larger than the shrinkage criterion ( 0.5%) for HDS [ 27 ]. This shrinkage problem can be relaxed to some extent by the addition of chain transfer agents by which rapid gelation is delayed and thereby shrinkage can be reduced [ 71 , 72 ]. In order to mitigate shrinkage further, we proposed the use of thiol-ene (TE)/thiol-yne (TY) monomers capable of free radical step growth polymerization in NPCs and showed a substantive reduction in shrinkage as low as 0.4 % without decreasing and S [ 73 – 77 ].…”

Design concepts for diffusive holographic photopolymers

“…For example, it has recently been shown that the addition of a chain transfer agent to a NP‐doped formulation results in a remarkable twofold improvement in usable Δ n , to as high as 0.016, without any increase in the nanoparticle loading (or, therefore, any increase in the formula limit). Instead, this improvement is attributed to more favorable reaction/diffusion kinetics, which also result in improved index response at high spatial frequencies …”

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate— Ionic Liquid Composites

“…In contrast, polymers offer much larger refractive-index modulations (up to ${10}^{-2}$ [3]), but are less controllable, e.g., with respect to shrinkage or thermal stability. Over the last two decades, the focus moved to polymer composite materials, such as polymer liquid crystal composites (H-PDLC [4,5,6,7,8,9], POLICRYPS [10,11,12]) or polymer nanoparticle composites [13,14,15,16,17,18,19,20,21,22,23]. Another recently introduced composite consists of ionic liquids embedded in a polymer matrix [24], the material investigated in this study.…”