Synthesis and characterization of biopolymer composites and their inorganic hosts.

摘要

Biopolymers are biodegradable and biocompatible materials obtained from renewable sources. These polymers could have an increased impact in consumer or health applications, given a larger, more flexible range of physical properties. Targeting enhanced properties through the design of organic-inorganic hybrids requires novel synthesis routes. An in-situ polymer composite that differs from hybrids generated by simple mixing of the organic and inorganic phases has been demonstrated here. A known ring opening polymerization catalyst was supported within the channels of mesoporous hosts (e.g. MCM-41). A combination of elemental analysis, solid-state nuclear magnetic resonance, surface area, and microscopy experiments indicated that the stannous octoate catalyst was supported inside the host channels, and that a charged framework is not required for its incorporation. These Sn(Oct)2 supported mesoporous catalysts were used to prepare poly(d,l-lactide) composites. Multiple experiments, including solid state NMR, BET nitrogen adsorption, and calorimetric analysis, gave evidence that the resulting polymer forms inside the host channels. In this way, a biopolymer which grows out of the crystallites is generated in-situ. Additionally, the acid catalyzed condensation polymerization of lactic acid with micro/mesoporous materials was investigated. Results indicate that Al-SBA-15 is a potential catalyst for improved composite synthesis, and are suggestive of higher molecular weights and no residual metal catalyst.