A comparative study of the activation of acetic acid and its chloro-derivatives by dimethylaniline in inducing vinyl photopolymerization
✍ Scribed by P. Ghosh; G.S. Mukherjee
- Publisher
- Elsevier Science
- Year
- 1986
- Tongue
- English
- Weight
- 275 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0014-3057
No coin nor oath required. For personal study only.
✦ Synopsis
Acetic, monochloroacetic, dichloroacetic and trichloroacetic acids readily initiate photopolymerization of methyl methacrylate at 40' with visible light when used in the presence of dimethylaniline (DMA) at catalytic concentrations (10 z 10 3 mol 1-t). The rate of polymerization (Rp) increases and the inhibition period (I.P.) decreases with increase in the degree of substitution with chlorine in the acid, using comparable concentrations of the acid (5 × I0 3 mol I L) and DMA (5 × 10 3 mol 1-L). When benzophenone (BP) is used as a photosensitizer in each of the above acid-amine photoinitiator systems, a similar trend of results is obtained; however, the BP-sensitized photopolymerization produces much lower I.P. and significantly higher Rp in each case. Spectrophotometric studies indicate that each acid forms a complex with DMA and that the complex is the actual initiating species. End-group analyses of polymers prepared using the acid amine initiator systems clearly indicates that initiation of polymerization takes place by radicals derived from the acid and DMA and generated by photodecomposition of the complex.