A new general approach to determine more accurate comonomer reactivity ratios in controlled/living radical copolymerization systems
✍ Scribed by Mahdi Abdollahi
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 507 KB
- Volume
- 122
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
Abstract
In controlled/living radical copolymerization (atom transfer radical copolymerization in this study) and in any other living chain‐growth copolymerization, the possible preferential addition of one of the comonomers onto the (macro)initiator‐derived (macro)radical can affect the copolymer composition, especially at low conversion; this results in inaccurate comonomer reactivity ratio estimation by the classic approach. A new general approach is introduced in this article, which allowed us to exclude the influence of the possible preferential addition of one of the comonomers onto the (macro)initiator‐derived (macro)radical on the copolymer composition at any conversion. According to this approach, copolymer chain grown during time t (t ≠ 0) is considered to be, in fact, the macroinitiator terminated with one of the comonomers under study, which will further grow during the time interval Δ__t__′ = t′ − t [where any reaction time t′ is considered to be grater than reaction time t, i.e. t′ > t] from a comonomer mixture with composition of f(t) [where f(t) is the molar ratio of comonomer i to comonomer j in the comonomer mixture] at time t. In such a situation, it is possible to obtain individual comonomer conversions [x~i~(Δ__t__′) and x~j~(Δ__t__′)], the overall comonomer conversion [x~ov~(Δ__t__′)], and the cumulative average copolymer composition for the copolymer formed during Δ__t__′, from which more accurate comonomer reactivity ratios can be calculated by the various low‐ or high‐conversion methods, depending on the overall comonomer conversion. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011