A Faster approach for the stereocomplex formation of high molecular weight polylactide using supercritical Dimethyl ether

Title
A Faster approach for the stereocomplex formation of high molecular weight polylactide using supercritical Dimethyl ether
Authors
GULNAZ BIBI정영미임종주김수현
Keywords
fast stereocomplex; dimethyl ether; high molecular weight polylactides; supercritical fluid technology
Issue Date
2015-05
Publisher
폴리머; Polymer(Korea)
Citation
VOL 39, NO 3, 453-460
Abstract
Engineering the polylactide via stereocomplexation with supercritical fluid (SCF) technology paved way to fabricate polymers with enhanced thermal and mechanical properties. We aimed to establish a SCF medium with excellent solubility for PLA without any additional solvent/co-solvent. We, therefore, employed supercritical dimethyl ether to synthesize 100% stereocomplex polylactide from high molecular weight homopolymers with an excellent yield. The remarkable solubility of the homopolymers in dimethyl ether is the key for quick conversion to s-PLA. This study proves a rapid synthesis route of dry s-PLA powder with sc-DME at 250 bar, 70 degrees C and 1.5 h, which are reasonably achievable processing parameters compared to the conventional methods. The degree of stereocomplexation was evaluated under the effect of pressures, temperatures, times, homopolymer-concentrations and molecular weights. An increment in the degree of stereocomplexation was observed with increased temperature and pressure. Complete conversion to s-PLA was obtained for PLLA and PDLA with M-n similar to 200 kg.mol(-1) with a total homopolymer to total DME ratio of 6:100% w/w at prescribed reaction conditions. The degree of stereocomplexation was determined by DSC and confirmed by XRD. Considerable improvement in thermo-mechanical properties of s-PLA was observed. DSC and TGA analyses proved a 50 degrees C enhancement in melting transition and a high onset temperature for thermal degradation of s-PLA respectively
URI
http://pubs.kist.re.kr/handle/201004/50389
ISSN
0379153X
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