Readily controllable step-growth polymerization method for poly(lactic acid) copolymers having a high glass
Saara Inkinen1, Mikael Stolt, Anders Södergård
1Tate and Lyle Finland Oy, FIN-20520 Turku, Finland.
Biomacromolecules
|March 30, 2010
Summary
Researchers developed novel poly(lactic acid) (PLA) copolymers with enhanced thermal properties. By copolymerizing lactic acid with specific polyfunctional carboxylic acids, they significantly increased the glass transition temperature (T(g)) of PLA materials.
Area of Science:
- Polymer Chemistry
- Materials Science
- Bioplastics
Background:
- Poly(lactic acid) (PLA) is a biodegradable polymer with a low glass transition temperature (T(g)) around 60°C, limiting its high-temperature applications.
- Enhancing the T(g) of PLA is crucial for expanding its use in demanding applications.
Purpose of the Study:
- To synthesize poly(lactic acid) (PLA) copolymers with significantly higher glass transition temperatures (T(g)) compared to traditional PLA homopolymers.
- To investigate the effect of different comonomers, specifically 1,4:3,6-dianhydro-D-glucitol (isosorbide, ISB), succinic acid (SA-2), 1,2,3,4-butanetetracarboxylic acid (BTCA-4), and 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (HCA-6), on PLA's thermal properties.
- To explore an alternative, easily operable melt-phase step-growth polymerization method for PLA production.
Main Methods:
- Copolymerization of lactic acid with ISB, SA-2, BTCA-4, and HCA-6 using step-growth polymerization in the melt phase.
- Characterization of the resulting copolymers to determine their glass transition temperatures (T(g)).
- Control over T(g) and cross-linking by adjusting polymerization time and temperature.
Main Results:
- PLA copolymers incorporating BTCA-4 and HCA-6 exhibited significantly increased T(g) values, reaching up to 80°C and 86°C, respectively.
- The melt-phase step-growth polymerization provided a simple and operable method for PLA production.
- T(g) and cross-linking could be effectively controlled by optimizing polymerization conditions.
- Linear copolymers with ISB and SA-2 did not show a similar T(g) improvement.
Conclusions:
- Polyfunctional carboxylic acids like BTCA-4 and HCA-6 are effective in enhancing the T(g) of PLA through copolymerization.
- Melt-phase step-growth polymerization offers a viable and straightforward route for producing high T(g) PLA copolymers.
- The choice of comonomer and polymerization conditions are critical for tailoring PLA's thermal performance.
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