Semibatch RAFT copolymerization of acrylonitrile and N-isopropylacrylamide: Effect of comonomer distribution on cyclization and thermal stability
| Autor: | Jeremy D. Moskowitz, Jeffrey S. Wiggins |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Materials science
Polymers and Plastics Comonomer Organic Chemistry Polyacrylonitrile Chain transfer 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences chemistry.chemical_compound Differential scanning calorimetry chemistry Polymerization Polymer chemistry Materials Chemistry Copolymer Thermal stability Acrylonitrile 0210 nano-technology |
| Zdroj: | Polymer. 84:311-318 |
| ISSN: | 0032-3861 |
| DOI: | 10.1016/j.polymer.2015.12.035 |
| Popis: | Utilizing reversible addition-fragmentation chain transfer (RAFT) polymerization, the composition profile of PAN-based copolymers becomes a tunable parameter in preparing carbon fiber precursors. In this work, poly(acrylonitrile-co-N-isopropylacrylamide) copolymers were prepared via a semibatch process mediated by 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT). The monomer reactivity ratios were determined by the Fineman-Ross (FR), Kelen-Tudos (KT), and non-linear least squares (NLLS) models. The number average sequence length of acrylonitrile (AN) was found to be highly dependent on the content of N-isopropylacrylamide (NIPAM). NIPAM was introduced at controlled rates into a reaction vessel in attempt to facilitate its distribution in the polymer backbone. These semibatch copolymers were evaluated based on their ring-closing cyclization efficiency, which was characterized by differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Significantly, DSC exotherms were reduced and cyclization occurred much faster reaching a greater thermal stability when NIPAM was introduced at slow feed rates. |
| Databáze: | OpenAIRE |
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