Synthesis of Advanced Materials from Renewable Resources
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The increasing awareness of the ecological problems caused by synthetic, non-degradable packaging films and the shortage of fossil fuels has prompted intensive research in the field of new biodegradable materials from renewable resources. Poly(l‑lactide) (PLA), which has started to be available in an industrial scale, has already replaced some petro-chemically based materials in short shelf-life applications. However, due to its inherent brittleness, broader implementation of PLA is still limited. Copolymerization of l‑lactide (LA) with flexible comonomers was shown to be the method of choice to improve the material properties.
In this study block copolyesters of LA and ε‑decalactone (DL) with micro-phase separated structures were prepared and hence new biomaterials from renewable resources were attained. The ability of DL to polymerize by ring-opening polymerization (ROP) using stannous octoate (Sn(Oct)2) and a metal-free N-heterocyclic carbene catalyst, respectively has been investigated. Bulk-ROP of DL using Sn(Oct)2 as the catalyst and benzyl alcohol as the initiator at 110 °C showed a linear increase in molecular weight with conversion. Furthermore the chain ends remained active after full conversion enabling sequential monomer addition.
Block copolymers of DL and LA were synthesized with well-defined macromolecular architectures and investigated by means of NMR, SEC, AFM, SEM, DSC and TGA. Solvent-casted films exhibited phase separated micro-structures, which provide a basis for thermoplastic elastomeric behavior.
Furthermore it was shown that the polymer architecture has crucial influence on the material properties and hence with the proper choice the materials can be tailored for specific applications. The degree of crystallinity and the glass transition temperatures, which affect the mechanical properties of the material, can be adjusted via block length and composition of the copolymer.
Place, publisher, year, edition, pages
ε Decalactone, ring-opening polymerization, block copolymers, micro-phase separation, thermoplastic elastomers
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-156309OAI: oai:DiVA.org:kth-156309DiVA: diva2:766141