TY - JOUR
T1 - Facile Access to Chain Length Dependent Termination Rate Coefficients via Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization
T2 - Influence of the RAFT Agent Structure
AU - Feldermann, Achim
AU - Stenzel, Martina H.
AU - Davis, Thomas P.
AU - Vana, Philipp
AU - Barner-Kowollik, Christopher
PY - 2004/4/6
Y1 - 2004/4/6
N2 - A recently developed methodology for determining chain length dependent termination rate coefficients, 〈kti,i〉, via reversible addition-fragmentation chain transfer (RAFT) polymerizations has been extended and validated for 1-phenylethyl phenyldithioacetate (PEPDA) and 3-benzylsulfanylthiocarbo-nylsulfanylpropionic acid (BSPA) mediated styrene (bulk) free radical polymerizations at 80°C. While the use of cumyl phenyldithioacetate (CPDA) enables a highly precise mapping of the chain length dependence of the termination rate coefficient, employment of PEPDA and BSPA leads to considerable information loss for short chain lengths (i < 10). Careful simulations demonstrate that such behavior is caused by a substantial decrease in the initial transfer effectiveness of the RAFT agents when going from CPDA to BSPA, leading to hybrid behavior between conventional and living free radical polymerization. The observed hybrid behavior is quantifiable via (overall) transfer rate coefficients for the individual RAFT agents in the preequilibrium step [CPDA (ktr,R = 5.0 × 105 L mol-1 s-1), PEPDA (ktr,R = 2.0 × 10 5 L mol-1 s-1), and BSPA (ktr,R = 1.0 × 104 L mol-1 s-1) at 80°C]. The underlying structural cause is the change from a tertiary (CPDA), via a secondary (PEPDA), to a primary (BSPA) leaving group in the initial RAFT agent. Further, the presented simulations open an efficient pathway for approximating overall preequilibrium transfer rate coefficients for the employed RAFT agents.
AB - A recently developed methodology for determining chain length dependent termination rate coefficients, 〈kti,i〉, via reversible addition-fragmentation chain transfer (RAFT) polymerizations has been extended and validated for 1-phenylethyl phenyldithioacetate (PEPDA) and 3-benzylsulfanylthiocarbo-nylsulfanylpropionic acid (BSPA) mediated styrene (bulk) free radical polymerizations at 80°C. While the use of cumyl phenyldithioacetate (CPDA) enables a highly precise mapping of the chain length dependence of the termination rate coefficient, employment of PEPDA and BSPA leads to considerable information loss for short chain lengths (i < 10). Careful simulations demonstrate that such behavior is caused by a substantial decrease in the initial transfer effectiveness of the RAFT agents when going from CPDA to BSPA, leading to hybrid behavior between conventional and living free radical polymerization. The observed hybrid behavior is quantifiable via (overall) transfer rate coefficients for the individual RAFT agents in the preequilibrium step [CPDA (ktr,R = 5.0 × 105 L mol-1 s-1), PEPDA (ktr,R = 2.0 × 10 5 L mol-1 s-1), and BSPA (ktr,R = 1.0 × 104 L mol-1 s-1) at 80°C]. The underlying structural cause is the change from a tertiary (CPDA), via a secondary (PEPDA), to a primary (BSPA) leaving group in the initial RAFT agent. Further, the presented simulations open an efficient pathway for approximating overall preequilibrium transfer rate coefficients for the employed RAFT agents.
UR - http://www.scopus.com/inward/record.url?scp=6344280414&partnerID=8YFLogxK
U2 - 10.1021/ma0358428
DO - 10.1021/ma0358428
M3 - Article
AN - SCOPUS:6344280414
SN - 0024-9297
VL - 37
SP - 2404
EP - 2410
JO - Macromolecules
JF - Macromolecules
IS - 7
ER -