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Keywords = photodeprotection

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11 pages, 1587 KB  
Communication
Thiol-Substituted Poly(2-oxazoline)s with Photolabile Protecting Groups—Tandem Network Formation by Light
by Niklas Jung, Fiona Diehl and Ulrich Jonas
Polymers 2020, 12(8), 1767; https://doi.org/10.3390/polym12081767 - 7 Aug 2020
Cited by 12 | Viewed by 4565
Abstract
Herein, we present a novel polymer architecture based on poly(2-oxazoline)s bearing protected thiol functionalities, which can be selectively liberated by irradiation with UV light. Whereas free thiol groups can suffer from oxidation or other spontaneous reactions that degrade polymer performance, this strategy with [...] Read more.
Herein, we present a novel polymer architecture based on poly(2-oxazoline)s bearing protected thiol functionalities, which can be selectively liberated by irradiation with UV light. Whereas free thiol groups can suffer from oxidation or other spontaneous reactions that degrade polymer performance, this strategy with masked thiol groups offers the possibility of photodeprotection on demand with spatio-temporal control while maintaining polymer integrity. Here, we exploit this potential for a tandem network formation upon irradiation with UV light by thiol deprotection and concurrent crosslinking via thiol-ene coupling. The synthesis of the novel oxazoline monomer 2-{2-[(2-nitrobenzyl)thio]ethyl}-4,5-dihydrooxazole (NbMEtOxa) carrying 2-nitrobenzyl-shielded thiol groups and its cationic ring-opening copolymerization at varying ratios with 2-ethyl-2-oxazoline (EtOxa) is described. The tandem network formation was exemplarily demonstrated with the photoinitator 2-hydroxy-2-methylpropiophenone (HMPP) and pentaerythritol tetraacrylate (PETA), a commercially available, tetrafunctional vinyl crosslinker. The key findings of the conducted experiments indicate that a ratio of ~10% NbMEtOxa repeat units in the polymer backbone is sufficient for network formation and in-situ gelation in N,N-dimethylformamide. Full article
(This article belongs to the Special Issue In-Situ Forming and Self-Healing Hydrogels)
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13 pages, 3554 KB  
Article
Photodeprotectable N-Alkoxybenzyl Aromatic Polyamides
by Kenichi Iwashita, Hironobu Katoh, Yoshihiro Ohta and Tsutomu Yokozawa
Polymers 2017, 9(7), 246; https://doi.org/10.3390/polym9070246 - 24 Jun 2017
Cited by 7 | Viewed by 6435
Abstract
N-alkoxybenzyl aromatic polyamides were synthesized by polycondensation of N-alkoxybenzyl aromatic diamine with equimolar dicarboxylic acid chloride in the presence of 2.2 equiv. of pyridine at room temperature for 2 days. The obtained polyamides were mainly cyclic polymers, as determined by means [...] Read more.
N-alkoxybenzyl aromatic polyamides were synthesized by polycondensation of N-alkoxybenzyl aromatic diamine with equimolar dicarboxylic acid chloride in the presence of 2.2 equiv. of pyridine at room temperature for 2 days. The obtained polyamides were mainly cyclic polymers, as determined by means of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, and showed higher solubility in organic solvents than unprotected aromatic polyamides. Photodeprotection of N-alkoxybenzyl aromatic polyamide film containing photo acid generator (PAG) proceeded well under UV irradiation (5 J/cm2), followed by heating at 130 °C for 15 min. The nature of the polymer end groups of N-alkoxybenzyl aromatic polyamides was found to be crucial for photodeprotection reactivity. These polymers are promising candidates for photosensitive heat-resistant materials for fine Cu wiring formation by electroless Cu plating of high-density semiconductor packaging substrates. Full article
(This article belongs to the Special Issue Functionally Responsive Polymeric Materials)
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