title: Nanoporous poly(lactide) by olefin metathesis degradation.
abstract: We describe an approach to ordered nanoporous poly(lactide) that relies on self-assembly of poly(butadiene)-poly(lactide) (PB-PLA) diblock copolymers followed by selective degradation of PB using olefin metathesis. The block copolymers were obtained by a combination of anionic and ring-opening transesterification polymerizations. The molar mass of each block was tailored to target materials with either a lamellar or cylindrical microphase-separated morphology. Orientation of these nanoscale domains was induced in thin films and monolithic samples through solvent annealing and mechanical deformation, respectively. Selective degradation of PB was achieved by immersing the samples in a solution of Grubbs first-generation catalyst in cyclohexane, a nonsolvent for PLA. Successful elimination of PB was confirmed by size-exclusion chromatography and (1)H NMR spectroscopy. Direct imaging of the resulting nanoporous PLA was obtained by scanning electron microscopy.
authors.affiliation: Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455-0431, USA.
authors.forename: Arthur
authors.initials: A
authors.lastname: Bertrand
authors.forename: Marc A
authors.initials: MA
authors.lastname: Hillmyer
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D002070:Butadienes / Q000737:chemistry*; D020724:Elastomers / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D011091:Polyesters / Q000737:chemistry*; D016062:Porosity
chemical_list: D000475:Alkenes; D002070:Butadienes; D020724:Elastomers; D011091:Polyesters; C033616:poly(lactide); C028834:polybutadiene