PREPARATION AND CHARACTERIZATION OF POLY(1,4-BUTADIENE-B-1,2-BUTADIENE)

Poly(1,4-butadiene-b-1,2-butadiene) diblock polymers have been prepared anionically by sequential addition of monomer using sec-butyllithium as initiator in cyclohexane. The first block is of low vinyl units and the second block is of high vinyl units in microstructure. 1,2-Dipiperidinoethane was used as complexing agent in order to change the mode of addition of butadiene from predominantly 1,4 to 1,2 addition. The diblock polymers were characterized using Raman spectroscopy, gel permeation chromatography (g.p.c.) and dynamic mechanical thermal analysis (d.m.t.a.). The increase in molecular weight after the second batch of monomer was added is confirmed by g.p.c. Raman spectroscopy shows the difference in microstructure of the two blocks. Phase separation has been found in two diblock samples through the observation of two T(g) values arising from low and high vinyl blocks.