Xanthates in RAFT Polymerization

Dual Thermo- and pH-Responsive Block Copolymer of Poly(N-isopropylacrylamide)-block-Poly(N,N-diethylamino Ethyl Acrylamide): Synthesis, Characterization, Phase Transition, and Self-Assembly Behavior in Aqueous Solution

“…For pH value higher than 6, the transmittance at 70 °C no longer declines to 0 with measured values at 44, 52, and 86% at pH 7, 8, and 9, respectively, and no detectable decrease in transmittance was observed at pH 10. In order to confirm the critical role of the end group in the observed behavior, a PN homopolymer was synthesized by using 2-mercaptopropionic acid methyl ester O -ethyl dithiocarbonate RAFT agent. , As expected, no significant pH-dependance of thermoresponsive behavior was observed for this homopolymer (Figure S13). The pH-dependence of T c can be attributed to the degree of ionization of the −COOH end group.…”

“…The synthesis of the monomer DEAEAM was successfully achieved using a previously described protocol (Figure S1). Well-defined thermo- and pH-responsive block copolymers comprising PNIPAM and PDEAEAM blocks were successfully synthesized by RAFT radical − polymerization using AIBN as free-radical initiator and CDTPA as a RAFT agent. This chain-transfer agent was chosen due to its known reactivity for both monomers leading to a well control of polymerization. , It is noteworthy that CDTPA used introduced a dodecyl and a carboxyl terminal groups which can affect the properties of the polymers in solution (vide infra).…”

RAFT-Based Polymers for Click Reactions

“…RAFT-based polymers are a versatile source of macromolecules with chain-end thiols, which are suitable for various thiol–X click reactions (X = -ene, -yne, Hal, etc.) and for further modification of chain-end functionality ( Scheme 13 ) [ 41 , 42 , 43 , 44 , 45 , 46 , 47 ].…”

“…The thermolysis of RAFT-based polymers helps to remove the ZC(=S) group and produce polymers with the C=C end group (except xanthates, see 3.1) [ 41 , 42 , 43 , 44 , 45 , 46 , 47 ]. Thermal stability of RAFT-based polymers, mechanism of thermolysis, and purity of the product depend on the nature of the terminal monomer unit and thiocarbonylthio species [ 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 , 173 , 174 , 175 , 176 , 177 , 178 ].…”

“…To meet this condition, one needs to use a RAFT agent that is effective in the polymerization of chosen monomers, to avoid side reactions (such as intermediate radical termination), and to choose an appropriate ratio of the RAFT agent to initiator ([RAFT agent]/[initiator] >> 1). Nowadays, hundreds of RAFT agents with various types of R and Z groups have been described and applied to the controlled synthesis of (co)polymers [ 41 , 42 , 43 , 44 ]. Besides, the approaches for quantitative modification of the thiocarbonylthio group, resulting in its conversion into –SH, –CH=CXY, –CH 2 –CHXY, –R′ (product of the free radical initiator decomposition), –O–NR 1 R 2 , etc., have been developed [ 45 , 46 , 47 ].…”