Renewable polymers (bioplastics) offer an alternative to petroleum-based polymers and reduced environmental impact through decreased petroleum dependence and a sustainable product lifecycle via renewable, biomass-derived monomers and completely degradable polymers. Applying green chemistry principles, melt polycondensations of 1,3-propanediol with malonic acid and 1,3-propanediol with itaconic acid were performed to produce poly(trimethylene malonte) (PTM) and poly(trimethylene itaconate) (PTI), respectively. Aluminum chloride was used as the catalyst and reaction temperatures from 125-175 °C and reaction times from 2-32 h were attempted in order to produce high yields and molecular weights (Mw). Gravimetric yields ranged from 20-95 wt.% for PTM and 20-85 wt.% for PTI. Both PTM and PTI contained ester and ether backbone bonds, as determined by Fourier transform infrared and nuclear magnetic resonance spectroscopy. Gel permeation chromatography showed both PTM and PTI to have a bi-modal Mw distributions centered at 1.4±0.1 kDa and 35±3 kDa for PTM and 1.0±0.1 kDa and 38±2 kDa for PTI. For PTM, a Tg of -64 °C and a Tm of 29 °C was identified using differential scanning calorimetry (DSC). A crystallization temperature for PTI was found at ~160 °C using DSC. A hydrolytic degradation study was performed at 25 °C on PTM and PTI in pH 5.4, 7, 9, and 11 aqueous solutions for up to 4 weeks. The introduction of K+ ions (in the KOH aq. solutions) interfered with the AAC2 and AAL1 ester hydrolysis mechanisms through acid-base interactions. PTM was found to be susceptible to hydrolytic degradation and lost ~37 wt.% through ester hydrolysis and showed a molecular weight reduction of ~0.8 kDa over 10,000 min for a pH range of 7 to 11. PTI was also found to be susceptible to hydrolytic degradation with ~22 wt.% decrease through ester hydrolysis and molecular weight reduction of ~0.25 kDa over 10,000 min for a pH range of 7 to 11. PTM is a low molecular weight, saturated, linear copolymer and PTI is a low molecular weight, unsaturated, branched copolymer. Both PTM and PTI are renewable copolymers produced using green chemistry and mild reactions conditions and were found to be susceptible to hydrolytic degradation.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-2472 |
| Date | 01 May 2010 |
| Creators | Rowe, Mathew Dennis |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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