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New photocleavable structures. II. α‐Cleavable photoinitiators based on pyridines

2003; Wiley; Volume: 42; Issue: 3 Linguagem: Inglês

10.1002/pola.10859

1099-0518

Robert Liska, D. Herzog,

Advanced Polymer Synthesis and Characterization

Abstract A series of novel pyridine‐based type I photoinitiators were synthesized. UV spectroscopy revealed absorption characteristics very similar to those of a commercially available hydroxyalkylphenone [2‐hydroxy‐2‐methyl‐1‐phenyl propan‐1‐one ( 1b )]. Photo‐differential scanning calorimetry was used to study the polymerization kinetics of lauryl acrylate photoinitiated by the new pyridines. Under a nitrogen atmosphere, a 3‐substituted derivative [2‐hydroxy‐2‐methyl‐1‐pyridin‐3‐yl‐propan‐1‐one ( 3b )] gave results comparable to those obtained with 1b . Measurements under air indicated decreased sensitivity toward oxygen quenching reactions. Additionally, pyridine derivatives showed good water solubility (4.9 g/100 mL). Preliminary steady‐state photolysis experiments with 2,2,6,6‐tetramethyl‐1‐piperidinyloxy as a radical scavenger were carried out, and the α‐cleavage mechanism was found to be the main reaction pathway. The quantum yields of α‐cleavage were approximately 0.30 ± 0.04 for 3b and 0.18 ± 0.03 for 1b . © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 752–764, 2004