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Investigations on the Photoinitiator‐free Photopolymerization of Acrylates by Vibrational Spectroscopic Methods
Author(s) -
Scherzer Tom,
Knolle Wolfgang,
Naumov Sergej,
Prager Lutz
Publication year - 2005
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200551157
Subject(s) - photopolymer , photoinitiator , materials science , fourier transform infrared spectroscopy , acrylate , polymerization , irradiation , spectroscopy , molar absorptivity , photochemistry , optics , monomer , chemistry , composite material , polymer , physics , quantum mechanics , nuclear physics
Photopolymerization of acrylates without photoinitiators was carried out by irradiation with short‐wavelength UV light from excimer lamps with an emission at 222 or 172 nm. Basic investigations on the reactivity of various acrylates and on the conditions under which they can be UV‐cured were performed by real‐time FTIR‐ATR spectroscopy. Depending on the molar extinction coefficients of a specific acrylate at the wavelength of irradiation, the absorption of the light within the coating leads to a pronounced intensity gradient which significantly influences polymerization rate and conversion. Accordingly, it limits the maximum thickness of the layer that can be cured (ranging from some hundreds of nanometres up to some micrometers). In addition to the basic studies, thin acrylate coatings were also cured on pilot scale. The actual conversion in the layer after UV irradiation was directly monitored by in‐line NIR reflection spectroscopy, and the resulting coatings were characterized by FTIR spectroscopy and hardness measurements.