TY  - JOUR
A1  - Skrabania, Katja
A1  - Miasnikova, Anna
A1  - Bivigou Koumba, Achille Mayelle
A1  - Zehm, Daniel
A1  - Laschewsky, André
T1  - Examining the UV-vis absorption of RAFT chain transfer agents and their use for polymer analysis
T2  - Polymer Chemistry
N2  - The absorption characteristics of a large set of thiocarbonyl based chain transfer agents (CTAs) were studied by UV-vis spectroscopy in order to identify appropriate conditions for exploiting their absorbance bands in end-group analysis of polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerisation. Substitution pattern and solvent polarity were found to affect notably the wavelengths and intensities of the pi-pi*- and n-pi*-transition of the thiocarbonyl bond of dithioester and trithiocarbonate RAFT agents. Therefore, it is advisable to refer in end group analysis to the spectral parameters of low molar mass analogues of the active polymer chain ends, rather than to rely on the specific RAFT agent engaged in the polymerisation. When using appropriate conditions, the quantification of the thiocarbonyl end-groups via the pi-pi* band of the thiocarbonyl moiety around 300-310 nm allows a facile, sensitive and surprisingly precise estimation of the number average molar mass of the polymers produced, without the need of particular end group labels. Moreover, when additional methods for absolute molar mass determination can be applied, the quantification of the thiocarbonyl end-groups by UV-spectroscopy provides a good estimate of the degree of active end group for a given polymer sample.
Y1  - 2011
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/37109
SN  - 1759-9954
VL  - 2
IS  - 9
SP  - 2074
EP  - 2083
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -