TY - JOUR
T1 - Effect of transfer agent, temperature and initial monomer concentration on branching in poly(acrylic acid) : a study by 13C NMR spectroscopy and capillary electrophoresis
AU - Lena, Jean-Baptiste
AU - Goroncy, Alexander K.
AU - Thevarajah, Joel J.
AU - Maniego, Alison R.
AU - Russell, Gregory T.
AU - Castignolles, Patrice
AU - Gaborieau, Marianne
PY - 2017
Y1 - 2017
N2 - Branching has been investigated in poly(acrylic acid) synthesized by conventional radical polymerization with and without chain transfer agent (CTA) at different temperatures and initial monomer concentrations. The average number of branches per monomer unit (i.e. degree of branching) was quantified by solution-state 13C NMR spectroscopy. The heterogeneity of branching (dispersity of the electrophoretic mobility distributions) was measured by capillary electrophoresis in the critical conditions (CE-CC). The degree of branching (DB) increases with the reaction temperature due to a rise in the frequency of reactions leading to branches, while the heterogeneity of branching remains steady. DB is lower in polymer synthesized with CTA. This decrease is due to either the CTA quenching the mid-chain radicals or a reduction of the rate of chain transfer to polymer relative to (chain-end) propagation. No influence of initial monomer concentration on DB and on the heterogeneity of branching was observed.
AB - Branching has been investigated in poly(acrylic acid) synthesized by conventional radical polymerization with and without chain transfer agent (CTA) at different temperatures and initial monomer concentrations. The average number of branches per monomer unit (i.e. degree of branching) was quantified by solution-state 13C NMR spectroscopy. The heterogeneity of branching (dispersity of the electrophoretic mobility distributions) was measured by capillary electrophoresis in the critical conditions (CE-CC). The degree of branching (DB) increases with the reaction temperature due to a rise in the frequency of reactions leading to branches, while the heterogeneity of branching remains steady. DB is lower in polymer synthesized with CTA. This decrease is due to either the CTA quenching the mid-chain radicals or a reduction of the rate of chain transfer to polymer relative to (chain-end) propagation. No influence of initial monomer concentration on DB and on the heterogeneity of branching was observed.
KW - branching ratios (nuclear physics)
KW - capillary electrophoresis
KW - nuclear magnetic resonance spectroscopy
KW - polymers
UR - http://handle.westernsydney.edu.au:8081/1959.7/uws:38977
U2 - 10.1016/j.polymer.2017.01.030
DO - 10.1016/j.polymer.2017.01.030
M3 - Article
SN - 0032-3861
VL - 114
SP - 209
EP - 220
JO - Polymer
JF - Polymer
ER -