Effect of configuration of a bulky aluminum initiator

The effect of configuration of an asymmetric bulky initiator 2,2’-[1,1’-binaphtyl-2,2’-diyl10 bis-(nitrylomethilidyne)]diphenoxy aluminum isopropoxide (Ini) on structure of copolymer of 11 asymmetric monomer L,L-lactide (Lac) with symmetric comonomer trimethylene carbonate (Tmc) 12 was studied using polarimetry, dilatometry, SEC and 13C NMR. When the S-enantiomer of Ini was 13 used the distribution in copolymer chains at the beginning of polymerization is statistical, with 14 alternacy tendency, changing next through a gradient region to homoblocks of Tmc. When, 15 however, R-Ini was used, the product formed was a gradient oligoblock one, with Tmc blocks 16 prevailing at the beginning, changing to Lac blocks dominating at end part of chains. Initiation of 17 copolymerization with the mixture of both initiator enantiomers (S:R = 6:94) gave multiblock 18 copolymer, of similar features but shorter blocks. Analysis of copolymerization progress required 19 complex analysis of dilatometric data, assuming different contraction coefficients for units located 20 in different triads. Comonomer reactivity ratios of studied copolymerizations were determined. 21