Weraporn Pivsa-Art

The Production of Poly(L-lactic acid) from 2-Steps Direct Polycondensation in 100 Kg Scale

Synthesis of poly(L-lactic acid), PLLA, in a mass scale production using 2-steps direct polycondensation methods was investigated. One hundred kilogram of L-lactic acid was esterified in a designed reactor under reduced pressure at elevated temperature in the first step, followed solid state polymerization, SSP. The synthesized PLLA from both laboratory (5 g) and mass (100 L) scales show comparable melting temperature, Tm (151 – 172 oC) and molecular weight (Mn) (10,000 -32,000) at the similar polymerization conditions. The appearances of synthesized PLLA are yellow-white solid powder. The results show high potential to produce environmental friendly polymer, PLLA, using non-complex facilities process.

Cyclic Oligolactic Acid in Direct Polycondensation PLLA and Its Extraction with Organic Solvent

The contents of poly(L-lactic acid) (PLLA) prepared by direct condensation polymerization without using a catalyst were studied. 1H NMR and mass spectrometry analyses suggested that PLLA contained cyclic oligo(L-lactic acid) (c-OLLA) with 3–20 repeat units. Notably, only c-OLLA was extracted and isolated using hexane or cyclohexane at 4°C; thus the hydrophobicity, topology, and temperature dependence of the solubility of the obtained PLLA enabled the selective extraction of c-OLLA. The effect of cyclic compounds on direct polycondensation and the potential for c-OLLA to form molecular inclusion complexes were also discussed.

Scale-Up of Polymerization Process of Biodegradable Polymer Poly(lactic acid) Synthesis Using Direct Polycondensation Method

Environmental problems from petroleum-based plastic wastes have been rapidly increasing in recent years. The alternative solution is focus on the development of environmental friendly plastic derived from renewable resource. Poly(lactic acid) (PLA) is a biodegradable polymer synthesized from biomass having potential to replace the petroleum-based non-degradable polymers utilizations. PLA can be synthesized by two methods: (1) ring-opening of lactide intermediate and (2) direct polycondensation of lactic acid processes. The latter process has advantages on high yields and high purity of polymer products, materials handling and ease of process treatments. The polymerization process of PLA synthesis has been widely studied in a laboratory scale. However, the mass scale production using direct polycondensation of lactic acid has not been reported. We have investigated the kinetics and scale-up process of direct polycondensation method to produce PLA in a pilot scale. The order of reaction is 2 and activation energy of lactic acid to lactic acid oligomers is 61.58 kJ/mol. The pre-polymer was further polymerized in a solid state polymerization (SSP) process. The synthesized PLA from both the laboratory and pilot scales show the comparable properties such as melting temperature and molecular weight. The appearance of synthesized PLA is yellow-white solid powder.

Interactions between cyclic oligo( l- lactic acid) and alkali metal ions in organic solvent

We investigated the interaction between cyclic oligo (l-lactic acid) (c-OLLA) and alkali metal ions, including sodium, potassium, rubidium, and cesium. The analysis was conducted by electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) in the presence of a mixture of c-OLLA with 21 or fewer repeat units, which was extracted from poly(l-lactic acid), and alkali metal ions. The results suggested that an interaction between c-OLLA and alkali ions exists only in solution, not in bulk. In addition, ESI-MS/MS analysis of higher m/z analytes suggested that formation of two kinds of c-OLLA with sodium ions occurred, and thus it is assumed that c-OLLA includes alkali ions in its inner cavity. The liquid–liquid ion transformation in the presence of sodium ions and c-OLLA further supports this interaction. c-OLLA was found to exhibit higher complexation efficiency than PLLA by extracting sodium ions from the aqueous phase to the organic phase.