Polylactic acid synthesis

L. Averous, "Polylactic acid synthesis, properties and applications," in B.N.a.G. A. eds.. Monomers, Polymers and Composites from Renewable Resources, Elsevier Limited Publication, pp. 433,2008. 

Khodabakhshi, K., Ehsani, M., Asgari, M., Ahmadi, S. Eebruty (2014). Polylactic acid synthesis. Project Report, Iran Polymer and Petrochemical Institute. 

Polylactic Acid Synthesis, Properties and Applications, L. Avimus... 

Averous L (2008) Polylactic acid synthesis, properties and applications. In Belgacem N, Gandini A (eds) Monomers, oligomers, polymers and composites from renewable resources. Elsevier,... 

V. Piemonte (ed.), Polylactic Acid Synthesis, Properties and Applications, Nova Publishers Inc., New York, USA, 2011, pp. 1-340. ISBN 978-1-621-00348-9. 

Palumbo, F., Pitarresi, G., Mandracchia, D., Tripodo, G., Giammona, G. (2006). New graft copolymers of hyaluronic acid and polylactic acid Synthesis and characterization. Carbohydrate Polymers, 66, 379—385. 

L. Av rous, Polylactic acid Synthesis, properties and applications, in Monomers, Polymers and Composites from Renewable Resources, M.N.B. Gandini, Ed., 2008, Elsevier Amsterdam. Chap. 21,433-450. 

FIGURE 5 Stepwise synthesis of a triblock copolymer (PCL-PLA-PCL) of PCL and polylactic acid using aluminum coordination catalysts to minimize randomization of the block structure by transesterification. (From Ref. 43.)... 

In addition to solvent uses, esters of lactic acid can be used to recover pure lactic acid via hydrolysis, which in-tum is used to make optically active dilactide and subsequently polylactic acid used for drag delivery system.5 This method of recovery for certain lactic acid applications is critical in synthesis of medicinal grade polymer because only optically active polymers with low Tg are useful for drug delivery systems. Lactic acid esters themselves can also be directly converted into polymers, (Figure 1), although the commercial route proceeds via ring-opening polymerization of dilactide. 

Silva et al. (2006) studied starch-based microparticles as a novel strategy for tissue engineering applications. They developed starch-based microparticles, and evaluated them for bioactivity, cytotoxicity, ability to serve as substrates for cell adhesion, as well as their potential to be used as delivery systems either for anti-inflammatory agents or growth factors. Two starch-based materials were used for the development of starch-based particulate systems (1) a blend of starch and polylactic acid (SPLA) (50 50 w/w) and (2) a chemically modifled potato starch, Paselli II (Pa). Both materials enabled the synthesis of particulate systems, both polymer and composite (with BG 45S5). A simple solvent extraction method was employed for the synthesis of SPLA and SPLA/BG microparticles, while for Pa and Pa/BG... 

The 3-stage process involves utilisation of plant sugars derived from photosynthetically fixed C02 as carbon sources in the fermentation of organic acids, alcohols and amino acids. These substances are then used as building blocks for the chemical synthesis of polymers. Examples of polymers using the 3-stage process include polylactic acid and polybutylene succinate. 

Figure 7.8 Synthesis of polylactic acid using renewable carbon source [16].

In an early study by Lin et al., insulin-loaded polylactic acid (PLA) microcapsules were synthesized by an emulsification-solvent evaporation process originally reported by Beck et al. Several parameters in the synthesis process were modified with the intention of optimizing the insulin release profile. Such modifications included variations in types, concentrations, and viscosities of protective colloids used in the emulsification process. Polyvinyl alcohol (PVA), when used as the protective colloid in the fabrication process, was found to produce the PLA microparticles in reproducible quality. Further studies revealed that the concentration PVA directly affects the PLA particle size and the surface characteristics of the microcapsules. With higher concentrations of PVA, microparticles tended to be smaller and to have a smoother surface. When the release profiles of the microcapsules were stud-... 

AVE 13] Averous L., Borreton M.E., et al, 9, Synthesis, properties, environmental and biomedical applications of polylactic acid . Handbook of Biopolymers and Biodegradable Plastics, William Andrew IhibUshing, Boston, MA, pp. 171-188,2013. 

R. (2009) Polylactic acid (PLA) synthesis and modifications a review. Front. Chem. China, 4, 259-264. 

The bio-related resin polylactic acid is well known as a renewable material. However, renewable materials such as this lack the mechanical and thermal properties to be of any practical use. hi order to overcome these drawbacks, the synthesis of clay nanocomposites based on renewable materials has been discussed. These materials are known as Green Nanocomposites [44] and are now forming a new sector in materials studies. 

The next two sections of this review chapter will introduce the reader to the world of lactic acid. The acid is both a key platform chemical of the biorefinery concept, from which other interesting molecules may be formed (Sect. 2), and a monomer for commercial bioplastic polylactic acid (PLA) (Sect. 3). In the platform approach, the assessment from Chap. 1 in this volume [23] proves its value, as it is an equally useful tool to seek out the most desired routes for transforming a biomass-derived platform molecule as it is to select the most relevant carbohydrate-based chemicals from a chemist s point of view. In what follows, the desired catalytic cascade from cellulose to lactic acid will be described (Sect. 4) as well as the specific catalytic data reported for different feedstock (Sects. 5 and 6). Section 7 will introduce the reader to recent synthesis routes for other useful AHA compounds such as furyl and vinyl glycolic acid, as well as others shown in Fig. 1. Before concluding this chapter, Sect. 8 will provide a note on the stereochemistry of the chemically produced AHAs. 

Produced by classical chemical synthesis using renewable biobased monomers or mixed sources of biomass and petroleum (i.e., polylactic acid or bio-polyester) ... 

Lactic acid reacts with diacid or diol to form telechelic polylactic acid, then through further a linking reaction it forms high-molecular-weight lactic acid copolymers [33, 44, 45]. Polymerization of a racemic mixture of L- and D-lactides usually leads to the synthesis of poly-DL-lactide (PDLLA)which is amorphous. Use of stereospecific catalysts can result in heterotactic PLA which is found to show crystallinity [46, 47]. The degree of crystallinity and many associated properties are greatly controlled by the ratio of D to l enantiomers in the polymer [48]. 

Lactic acid used to be an important molecule for the chemical and food industries for centuries. It is produced through anaerobic fermentation by many bacteria. Traditionally its main applications are in the food industry where it is used as a natural acidifying agent. More recently, the scope of its applications was significantly enlarged by the synthesis of polylactic acid (PLA) as a new biodegradable and bio-based bioplastic. ... 

Although already discovered in 1780 by the Swedish chemist Carl Wilhelm Scheele,who isolated the lactic acid from sour milk, lactic acid has attracted more recently a great deal of attention due to its widespread applications, mainly in food, chemical, cosmetic, and pharmaceutical industries. Also, it has a great potential for the production of biodegradable and biocompatible polylactic acid (PLA) and, besides 3-hydroxypropionic acid, as an intermediate for sugar-based acrylic acid. Lactic acid production can be achieved either by chemical synthesis routes or by fermentative production (lactic acid fermentation). By the chemical synthesis route, a racemic mixture of DL-lactic acid is usually... 

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