Photochemical Reactions of Poly(4‐vinylphenol) Thin Films

Abstract

The mechanism involved in the photochemical immobilization of poly(4‐vinylphenol) (PVP) thin films was investigated. The films were fabricated by a simple procedure of UV irradiation and solvent extraction. A combination of ellipsometry, IR, and high‐resolution X‐ray photoelectron spectroscopy (XPS) was used to provide detailed and quantitative analysis of the composition of the photochemical reaction products. Upon irradiation at 260 nm, benzyl and phenoxy radicals are generated in the polymer. In the absence of oxygen, PVP films crosslinked via the combination of the benzyl radicals or phenoxy radicals. At lower irradiation doses, the photochemical process was dominated by crosslinking of the polymer backbone via the combination of benzyl radicals. At higher exposure doses, crosslinked quinoid structures were generated, and the concentration increased with the irradiation time. No oxidation or degradation products were observed. In the presence of oxygen, additional reactions of oxidation and degradation occurred. At lower doses, oxidation at the benzyl position produced the ketone structure evidenced by the drastic increase in the O content in the irradiated films. As the irradiation doses increased, further oxidation at the methylene position occurred, and in addition, volatile and degradation products were also generated. This photochemical process was successfully employed to fabricate patterned PVP structures.magnified image

Following laser induced changes of plant phenylpropanoids by Raman microscopy

“…4-Vinylphenols like coniferyl alcohol can undergo photochemical reactions upon UV irradiation 63 and the polymerization of coniferyl alcohol was already studied in several papers by Radotic and co-workers 64 , 65 . They produced so-called photopolymers by exposing coniferyl alcohol to UV light.…”

Analysis of the surface density and reactivity of perfluorophenylazide and the impact on ligand immobilization

“…20,26,27,30,31 The measured values were 26. NEXAFS carbon K-edge spectra for the 100% PFPA-MUTEG films as well as the mixed PFPA-MUTEG/MDEG films prepared from 90:10 and 80:20 solutions acquired at an angle of 55 between the incident x-ray beam and the surface plan are shown in Fig.…”

Ionization of covalent immobilized poly(4-vinylphenol) monolayers measured by ellipsometry, QCM and SPR

“…PVP was then spin-coated on the surface followed by irradiating using a medium pressure Hg lamp. Irradiation of PVP by deep UV results in the formation of quinone-type structures [39], which are no longer electrolytes and would not have pH responsive properties. Deep UV would also crosslink the polymer [39,40].…”

“…Irradiation of PVP by deep UV results in the formation of quinone-type structures [39], which are no longer electrolytes and would not have pH responsive properties. Deep UV would also crosslink the polymer [39,40]. To avoid these issues, a 280-nm optical filter was placed on the PVP films during irradiation to remove the deep UV from the light source.…”