title: Micro- to nanoscale structure of biocompatible PLA-PEO-PLA hydrogels.
abstract: We observe large-scale structures in hydrogels of poly(l-lactide)-poly(ethylene oxide)-poly(l-lactide) (PLLA-PEO-PLLA) ranging in size from a few hundred nanometers to several micrometers. These structures are apparent through both ultra-small angle scattering (USAS) techniques and confocal microscopy. The hydrogels showed power law scattering in the USAS regime, which is indicative of scattering from fractal structures. The fractal dimension of the scattering from hydrogels revealed that the gels have large size aggregates with a mass fractal structure over the nanometer-to-micrometer length scales. The aggregates also seem to become more "dense" with an increase in the molecular weight of crystalline PLLA domains. Visualization through confocal microscopy confirms that the gels have a microstructure of interspersed micrometer-sized polymer inhomogeneities with water channels running between them. The presence of micrometer-sized water channels in the hydrogels has very important implications for biomedical applications.
authors.affiliation: Department of Chemical Engineering, University of Massachusetts, Amherst, 686 North Pleasant Street, Amherst, Massachusetts 01003, USA.
authors.forename: Sarvesh K
authors.initials: SK
authors.lastname: Agrawal
authors.forename: Naomi
authors.initials: N
authors.lastname: Sanabria-Delong
authors.forename: Pete R
authors.initials: PR
authors.lastname: Jemian
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Tew
authors.forename: Surita R
authors.initials: SR
authors.lastname: Bhatia
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D020100:Hydrogels / Q000737:chemistry*; D018613:Microscopy, Confocal; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D011091:Polyesters / Q000138:chemical synthesis / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry*; D053838:Scattering, Small Angle; D012680:Sensitivity and Specificity; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D011091:Polyesters; C507889:polylactide-polyethylene glycol-polylactide; D011092:Polyethylene Glycols