Polymers polylactic acid

It polymerises to form the polymer, polylactic acid (PLA) which is biodegradable, a Suggest two advantages that PLA has compared with a polymer made from petroleum. [2]... 

Dainippon Ink Chemicals Inc. offers a polyester based impact modifier specifically for use in the biodegradable polymer, polylactic acid. Arakawa Chemical has developed biodegradable plasticisers for what is expected to be a rapidly expanding market associated with Cargill Dow s polylactic acid product. 

Homo- polymer Polylactic acid (PLA) Ring-opening polymerization of lactide... 

Synthetic polymers. Polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCA), polyamino acids, polyethylene (PE) and high molecular weight derivatives, polysulfone, polyhydroxybutyrate. 

Braided Synthetic Absorbable Sutures. Suture manufacturers have searched for many years to find a synthetic alternative to surgical gut. The first successful attempt to make a synthetic absorbable suture was the invention of polylactic acid [26023-30-3] suture (15). The polymer was made by the ring-opening polymerization of L-lactide [95-96-5] (1), the cycUc dimer of L-lactic acid. 

Bio-based materials are materials that are taken from or made from natural materials in living things. Examples include packing pellets made from corn and soybeans, polylactic acid (a polymer used to make plastic packaging), and various kinds of pharmaceuticals. 

Polymer blends have been categorized as (1) compatible, exhibiting only a single Tg, (2) mechanically compatible, exhibiting the Tg values of each component but with superior mechanical properties, and (3) incompatible, exhibiting the unenhanced properties of phase-separated materials (8). Based on the mechanical properties, it has been suggested that PCL-cellulose acetate butyrate blends are compatible (8). Dynamic mechanical measurements of the Tg of PCL-polylactic acid blends indicate that the compatability may depend on the ratios employed (65). Both of these blends have been used to control the permeability of delivery systems (vide infra). 

Whereas conventional poly (amino acids) are probably best grouped together with proteins, polysaccharides, and other endogenous polymeric materials, the pseudopoly (amino acids) can no longer be regarded as "natural polymers." Rather, they are synthetic polymers derived from natural metabolites (e.g., a-L-amino acids) as monomers. In this sense, pseudopoly (amino acids) are similar to polylactic acid, which is also a synthetic polymer, derived exclusively from a natural metabolite. 

Polylactic acid (PLA) has been produced for many years as a high-value material for use in medical applications such as dissolvable stitches and controlled release devices, because of the high production costs. The very low toxicity and biodegradability within the body made PLA the polymer of choice for such applications. In theory PLA should be relatively simple to produce by simple condensation polymerization of lactic acid. Unfortunately, in practice, a competing depolymerization process takes place to produce the cyclic lactide (Scheme 6.10). As the degree of polymerization increases the rate slows down until the rates of depolymerization and polymerization are the same. This equilibrium is achieved before commercially useful molecular weights of PLA have been formed. 

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. 

Hartmann, M.H. (1998). High molecular weight polylactic acid polymers. In Kaplan, D.L., editor. Biopolymers from Renewable Resources. Springer, Berlin. 

Abstract Synthetic polymers and biopolymers are extensively used within the field of tissue engineering. Some common examples of these materials include polylactic acid, polyglycolic acid, collagen, elastin, and various forms of polysaccharides. In terms of application, these materials are primarily used in the construction of scaffolds that aid in the local delivery of cells and growth factors, and in many cases fulfill a mechanical role in supporting physiologic loads that would otherwise be supported by a healthy tissue. In this review we will examine the development of scaffolds derived from biopolymers and their use with various cell types in the context of tissue engineering the nucleus pulposus of the intervertebral disc. 

Since 1989, Cargill, has invested some 750 million to develop and commercialize polylactic acid (tradename NatureWorks). Its Nebraska plant, with an annual capacity of 140,000 metric tons, opened in 2002. Thus, polylactides, combining favorable economics with green sustainability, are poised to compete in large-volume markets that are now the domain of thermoplastic polymers derived from petrochemical sources. 

Polylactic acid Ethyllactate Thermoplastic polymer Solvent, intermediate... 

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 use of biodegradable polymers, especially polylactic acid (PLA), in oral solid dosage forms has been reported in the literature. PLA has been used as a matrix for phenobarbital tablets (9). Similarly, the use of polylactide as a matrix for oral dosage form of naproxen has also been reported (10). 

Table 4 A Partial List of Marketed Drug Delivery Products Utilizing Polylactic Acid or Poly(lactic-co-glycolic) Acid Polymers...

DL-Polylactic acid, for the most part, was found to erode in about 12 months. Slow degradation of DL-polylactic acid often becomes a limitation on its use. This rate can be accelerated appreciably by copolymerizing with up to 50 mol% glycolide to yield complete erosion in as fast as 2 to 3 weeks. Incorporation of glycolide into the polylactide chain alters crystallinity, solubility, biodegradation rate, and water uptake of the polymer. 

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