Photopolymerization of methyl methacrylate: effects of photochemical and photonic parameters on the chain length
- 11 July 2014
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Polymer Chemistry
- Vol. 5 (21), 6236-6243
- https://doi.org/10.1039/c4py00550c
Abstract
The effects of photochemical and photonic parameters are investigated on the chain length of poly(methylmethacrylate) (PMMA) as formed by the free radical photopolymerization process. Different photoinitiators were tested for the photopolymerization of PMMA. The Type II system based on isopropyl thioxanthone (ITX)–ethyl 4-(dimethylamino)benzoate (EDB) gave the best result. The conversion reaches 80% in 20 min contrary to Type I photoinitiators. The decrease of the ITX concentrations from 3 wt% to 0.05 wt% allows the formation of higher chains of PMMA with Mw = 170 000 g mol−1, thanks to the decrease in photogenerated radicals. However, there was almost no influence of light intensity on polymer chains. To optimize the chain length of photopolymerized PMMA, Triazine A (TA) was added to reduce the formation of ketyl radicals arising from the reaction of ITX with EDB. The mechanism of the reaction of this three-component photoinitiating system studied by LFP confirmed the creation of ketyl radicals and their oxidation by TA. Then, the use of this three-component system increases both the kinetics of polymerization and the final conversion by virtue of the decrease in ketyl radicals, which act as terminating agents, and a concomitant increase of initiating radicals as formed from the reduced TA. Moreover, thanks to these new sources of initiating radicals, photopolymerization can take place at lower intensity of light. With TA, it was found possible to photopolymerize under very soft conditions and to allow the formation of longer polymer chains with Mw = 200 000 g mol−1 at 1 mW cm−2.Keywords
This publication has 34 references indexed in Scilit:
- Free radical formation in three-component photoinitiating systemsPolymer, 2012
- Influence of molecular weight of polymethyl(methacrylate) beads on the properties and structure of cross-linked denture base polymerJournal of the Mechanical Behavior of Biomedical Materials, 2011
- Continuous Distribution Kinetics for Photopolymerization of Alkyl MethacrylatesMacromolecular Reaction Engineering, 2009
- A photo‐oxidizable kinetic pathway of three‐component photoinitiator systems containing porphrin dye (Zn‐tpp), an electron donor and diphenyl iodonium saltJournal of Polymer Science Part A: Polymer Chemistry, 2009
- A photo-polymerization resist for UV nanoimprint lithographyMicroelectronic Engineering, 2009
- Photopolymerization reactions initiated by a visible light photoinitiating system: Cyanine dye/borate salt/1,3,5-triazineJournal of Polymer Science Part A: Polymer Chemistry, 2007
- Approaches towards a technically feasible photoinitiated prepolymerization of methyl methacrylateChemical Engineering and Processing - Process Intensification, 2004
- Light‐induced crosslinking polymerizationPolymer International, 2002
- Mechanistic Studies of Photoacid Generation from Substituted 4,6-Bis(trichloromethyl)-1,3,5-triazinesChemistry of Materials, 1997
- Fatigue crack propagation in poly(methyl methacrylate): Effect of molecular weight and internal plasticizationPolymer Engineering & Science, 1977