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Title: Water transport and clustering behavior in homopolymer and graft copolymer polylactide

Polylactide is a bio-based and biodegradable polymer well-known for its renewable origins. Water sorption and clustering behavior in both a homopolymer polylactide and a graft copolymer of polylactide was studied using the quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) technique. The graft copolymer, poly(1,5-cyclooctadiene-co-5-norbornene-2-methanol-graft-D,L-lactide), contained polylactide chains (95 wt.%) grafted onto a hydrophobic rubbery backbone (5 wt.%). Clustering is an important phenomenon in the study of water transport properties in polymers since the presence of water clusters can affect the water diffusivity. The HCC method using the thermal power signals and Van't Hoff's law were both employed to estimate the water sorption enthalpy. Sorption enthalpy of water in both polymers was determined to be approximately -40 kJ/mol for all water activity levels. Zimm-Lundberg analysis showed that water clusters start to form at a water activity of 0.4. The engaged species induced clustering (ENSIC) model was used to curve fit sorption isotherms and showed that the affinity among water molecules is higher than that between water molecules and polymer chains. All the methods used indicate that clustering of water molecules exists in both polymers.
Authors:
; ; ; ;  [1] ;  [2]
  1. (Drexel)
  2. (
Publication Date:
OSTI Identifier:
1049559
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Membrane Sci.; Journal Volume: 396; Journal Issue: 04, 2012
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
DOE - OTHERNSF
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; ACTIVITY LEVELS; AFFINITY; CALORIMETRY; CHAINS; COPOLYMERS; ENTHALPY; ISOTHERMS; POLYMERS; QUARTZ; SORPTION; TRANSPORT; WATER