Microstructure and glass-transition temperature of novel star N-SIBR

In this study, a polymeric N-functionalized mutilithium (N-M-Li) compound was prepared from commercial divinylbenzene (DVB) and lithiohexamethyleneimine (LHMI), and star-shaped copoly(styrene-butadiene-isoprene) was obtained by anionic polymerization using preformed N-M-Li as initiator, tetramethylethlenediamine (TMEDA) as polar modifier, and cyclohexane as solvent. The microstructure and the glass-transition temperature (Tg) of copolymers were characterized by H-1 NMR and differential scanning calorimetry (DSC), respectively. It showed that the non-1,4-structure content and the Tg of copolymers increased with the increase of TMEDA dosage or the decrease of polymerization temperature; however, the effects of the initiator concentration and DVB dosage on them were not obvious. We also obtained the relationships between the non-1,4-structure content of copolymers and the Tg of copolymers respectively, and between the In(T/Li) (TMEDA/N-M-Li, mole ratio) and the non1,4-structure content of copolymers, as follows: Tg (degrees C) = 0.6258C(non)-55.93 and C-non (1,4) = 20.79 In K+59.11, where K is T/Li value. Therefore on the basis of experimental results, we realize polymer design according to our practical requirements. (c) 2006 Wiley Periodicals, Inc.