Preparation of a Water-Based Photoreactive Azosulphonate-Doped Poly(Vinyl Alcohol) and the Investigation of Its UV Response

Abstract

Two different azosulphonate dyes were synthesised and purified for the preparation of a water-based photoreactive azosulphonate-doped poly(vinyl alcohol). The aim was the investigation of a novel azosulphonate-poly(vinyl alcohol) photoresist with decreased water solubility after illumination, setting a focus on environmentally benign substances. The electron distribution of the aromatic rings of the two different azosulphonate molecules were changed by the UV-induced cleavage of the –N=N–SO3− groups, which was evidenced by UV spectroscopy. The formation of ester groups was detected by Fourier-transform infrared and 13C nuclear magnetic resonance spectroscopy. UV–Vis spectroscopy was used to investigate the photoreactivity of the prepared films. Photolithographic experiments demonstrated the applicability of these newly produced materials as photoresist materials. In addition, these materials provide high thermal stability.

Gentle Patterning Approaches toward Compatibility with Bio‐Organic Materials and Their Environmental Aspects

“…As well as the resists developed by Wilson's group, those also required a post-exposure backing procedure. Recent paper by Nothdurft et al [96] proposed azosulphonate-doped PVA as a negative tone water-developable photoresist, which allowed to eliminate the post-exposure backing procedure. Finally, in 2020 a dextrin-based negative tone photoresist was applied by Toru Amano et al [121] Speaking of positive tone resists, we should mention a successful realization of a water-processable resist in 1999 by Guo et al [122] This research group utilized copolymer Langmuir-Blodgett films of N-(2,2-dimethylpropyl)methacrylamide (DMA) and Nphenylmethacrylamide (PhMA), which delivered 0.75 µm resolution with a Hg lamp exposure.…”

“…Colors are used to specify compatibility: red -limited, many bio-organic samples may not withstand this particular step or feature; yellow -mild detrimental processing; green -highly compatible. (SSS) copolymer with phydroxy-Nphenylmethacrylamide) [95] -H2O 120 (20) 1100-26600 Glyceryl methacrylate and methacrolein [120] AZO doped PVA [96] -H2O Pendant ammonium salts of half-esters of malonic acids and acid-labile alkyl esters [124] + H2O 165 ( 5 Maskless projection lithography for protein patterning [131] +…”

“…OL allows patterning with 0.5 µm resolution in direct writing setups and regular mask projection schemes. There are three principal approaches to prepare water-soluble photoresists, which, being photochemical reactions, usually follow the radical mechanism: photoactivated cross-linking, [95][96][97][98] photoelimination/ photodeprotection, [99][100][101] and photo-induced rearrangement/ photoisomerization. [102] Aqueous-based development always requires a change in the resist polarity or phase state.…”

“…Recent paper by Nothdurft et al. [ 96 ] proposed azosulphonate‐doped PVA as a negative tone water‐developable photoresist, which allowed to eliminate the postexposure backing procedure. Finally, in 2020 a dextrin‐based negative tone photoresist was applied by Amano et al.…”

Dyedauxiliary Groups, an Emerging Approach in Organic Chemistry. The Case of Arylazo Sulfones

“…61 Recently, a set of water-based azosulfonate-doped poly(vinyl alcohols) (28, Figure 4a) was prepared and tested as a highly thermally stable photoresist material. 62 Dunkin et al exploited the reactivity of arylazo sulfonates to develop a new class of visible-light photoactive surfactants (29, Figure 4b) 63 that were later employed as photolabile emulsifiers in the polymerization of methylmethacrylate. 64 Sodium 4-hexylphenylazosulfonate 30 (Figure 4c) was used as photolabile surfactant in photoresposive emulsions.…”