Synthesis and nanoimprinting of high refractive index and highly transparent polythioethers based on thiol‐ene click chemistry

Abstract

This work demonstrates the UV nanoimprinting lithography (UV‐NIL) of high refractive index and highly transparent polythioethers based on thiol‐ene click chemistry. Herein, 9,9‐bis(3‐mercaptopropylphenylether)fluorene (BMPF) is designed as a new thiol monomer with a high refractive index, high transparency, and good processability for UV‐NIL. Colorless polythioethers are synthesized from BMPF and ene monomers under mild thiol‐ene click reaction conditions. Excellent transmittance (96%) of 400 nm light is observed in all the polymer films and high refractive index values of 1.5972–1.6382 are attained. UV‐NIL using thiol‐ene photopolymerization affords polymer nanoimprinting patterns with various features on the order of 100–500 nm without any fractures. To the best of our knowledge, this is the first report on UV‐NIL of high refractive index and highly transparent polymers. Through proper monomer and polymer design, novel polythioethers with suitable glass transition temperature (T g) values are developed with high refractive index, high transparency, and good UV‐NIL processability. Furthermore, UV‐NIL based on thiol‐ene click chemistry is accomplished at the nanoscale. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2175–2182

Synthesis of aliphatic polymers with high refractive index by photoinduced polyaddition of thiols to bifunctional allyl monomer containing tetrathiaspiro structure

“…This increase was ascribed to the rather large values of n D 25 of T1 and T2 , namely, 1.630 and 1.641, respectively, and to the increase of the molecular density by the crosslinking. Incidentally, this value was similar to that of the polymer, namely 1.638, which was obtained by the photocuring reaction of bisacrylate having arylthioether structure and the bisthiol having diarylfluorene structure . The values of P1 and P2 are rather large for the values of aliphatic polymers having neither aromatic ring nor halogens.…”

“…Of various polymerization reactions, thiol–ene reaction is fit for the photocuring reaction because it rarely suffers oxygen inhibition and their polymerization proceeds fast to result polymers that have uniform crosslink density with high conversion rate and low shrinking . Recently, the study of the UV nanoimprinting by using the photoinduced thiol–ene reaction between bisacrylate having arylthioether structure and bisthiol having diarylfluorene structure was reported . Unfortunately, problems are cast by the fact that both monomers are solid at room temperature due to the effect from aryl rings requiring the use of solvent on carrying out the photocuring process and that the refractive index of the resulted polymer film is lower in comparison with those of the existing thermoplastic polymers that possess arylthioether structure .…”

UV-Cured Transparent Flexible Silicone Materials with High Tensile Strength

“…Finally, as we know, transparent silicone materials prepared by traditional curing methods suffer from the disadvantages of long curing time and high energy consumption. , The UV curing method has drawn much attention in the fields of electronics, coatings, printing inks, and adhesives owing to their numerous merits over the traditional thermal curing method including low volatile organic compounds emissions, low energy consumption, fast curing at ambient temperature, and short cycle time. ,− The thiol–ene reaction initiated by UV light has been used increasingly in polymer synthesis because of their merits such as highly effective under mild reaction conditions, without a photoinitiator, extremely tolerant to a variety of functional groups, without oxygen inhibition, and lack of byproduct. ,− Therefore, the thiol–ene reaction has been utilized to prepare silicone elastomers under mild reaction conditions. , …”

An Easy Fabrication Method to Prepare Inexpensive UV–Cured Transparent Silicone Modified Polyacrylate Coatings with Good Adhesion and UV Resistance

“…It is convinced that UV photoinitiators will increase the cost and the risks of turning yellow of the UV-cured materials. As reported, the thiol-ene reaction initiated by UV light has attracted much attention in polymer science for their virtues such as high activity at mild condition, without photoinitiator and rather tolerant to various functional groups [9][10][11][12][13]. From this point, the attempts to develop silicone modified polyacrylates by UV initiated thiol-ene reaction also have potentials to reduce the cost and the risks of turning yellow of the products.…”