Postpolymerization by using long-lived poly(di-2-ethylhexyl itaconate) radicals in the gel formed by (r)-12-hydroxystearic acid
✍ Scribed by M. Seno; Y. Kiso; H. Tanaka; T. Sato
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 393 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0014-3057
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✦ Synopsis
Long-lived propagating polymer radicals were observed to be produced in the photopolymerization of di-2-ethylhexyl itaconate (DEHI) with di-tert-butyl peroxide in the gel formed by (R)-12-hydroxystearic acid (HSA). The postpolymerization was attempted by using the long-lived poly(DEHl) radicals in the gel. The polymer yield in the postpolymerization increases linearly with time in the temperature range from 0 to 40 ° under the conditions of no further generation of radicals. The activation energy of postpolymerization was calculated to be 51.1 kJ/mol which seems to correspond to that of propagation via a diffusion-controlled mechanism. The rate of postpolymerization (Rp) increases in proportion to the 1.4th order of the monomer concentration, while Ro decreases somewhat with the HSA concentration. The molecular weights of polymers obtained are almost independent of the conversion, suggesting that chain-transfer plays an important role in the postpolymerization. The tacticity of the resulting polymers is different from that of the polymer formed by the conventional photopolymerization of DEHI, indicating that the gel controls the steric course of propagation reaction. Application of a magnetic field (4000 G) was also found to accelerate fairly the postpolymerization.