A literature review is presented regarding the synthesis, and physicochemical, chemical, and mechanical properties of poly(lactic acid)(PLA). Poly(lactic acid) exists as a polymeric helix, with an orthorhombic unit cell. The tensile properties of PLA can vary widely, depending on whether or not it is annealed or oriented or what its degree of crystallinity is. Also discussed are the effects of processing on PLA. Crystallization and crystallization kinetics of PLA are also investigated. Solution and melt rheology of PLA is also discussed. Four different power-law equations and 14 different Mark–Houwink equations are presented for PLA. Nuclear magnetic resonance, UV–VIS, and FTIR spectroscopy of PLA are briefly discussed. Finally, research conducted on starch–PLA composites is introduced.

/pdf/a-literature-review-of-poly-lactic-acid-559pd7jgnc.pdf

A Literature Review of Poly(Lactic Acid)

4.3. Reaction Mechanism 2373 4.4. Asymmetric Synthesis 2374 4.5. Outlook 2374 5. Alternating Polymerization of Oxiranes and CO2 2374 5.1. Reaction Outlines 2374 5.2. Catalyst 2376 5.3. Asymmetric Polymerization 2377 5.4. Immobilized Catalysts 2377 6. Synthesis of Urea and Urethane Derivatives 2378 7. Synthesis of Carboxylic Acid 2379 8. Synthesis of Esters and Lactones 2380 9. Synthesis of Isocyanates 2382 10. Hydrogenation and Hydroformylation, and Alcohol Homologation 2382

Transformation of carbon dioxide.

Polylactic acid is proving to be a viable alternative to petrochemical-based plastics for many applications It is produced from renewable resources and is biodegradable, decomposing to give H2O, CO2, and humus, the black material in soil In addition, it has unique physical properties that make it useful in diverse applications including paper coating, fibers, films, and packaging (see Figure)

Polylactic Acid Technology

s, and 360 patents, and edited 12 books. He has also received over 80 major awards including the Gairdner Foundation International Award, Lemelson-MIT prize, ACS’s Applied Polymer Science and Polymer Chemistry Awards, AICHE’s Professional Progress, Bioengineering, Walker and Stine Materials Science and Engineering Awards. In 1989, Dr. Langer was elected to the Institute of Medicine of the National Academy of Sciences, and in 1992 he was elected to both the National Academy of Engineering and the National Academy of Sciences. He is the only active member of all three National Academies. Kevin Shakesheff was born in Ashington, Northumberland, U.K., in 1969. He received his Bacheclor of Pharmacy degree from the University of Nottingham in 1991 and a Ph.D. from the same institution in 1995. In 1996 he became a NATO Postdoctoral Fellow at MIT, Department of Chemical Engineering. He is currently an EPSRC Advanced Fellow at the School of Pharmaceutical Sciences, The University of Nottingham. His research group investigates new methods of engineering polymer surfaces and the application of these engineered materials in drug delivery and tissue engineering. 3182 Chemical Reviews, 1999, Vol. 99, No. 11 Uhrich et al.

Polymeric Systems for Controlled Drug Release

RGD modified polymers: biomaterials for stimulated cell adhesion and beyond

Solution-grown lamellar crystals of poly(p-dioxanone) (PPDX) have been crystallized isothermally from butane-1,4-diol at 100°C The crystal structure of PPDX has been determined by interpretation of X-ray fiber diagrams of PPDX fibers and electron diffraction diagrams of lozenge-shaped chain-folder lamellar crystals The unit cell of PPDX is orthorbombic with space group P2 1 2 1 2 1 and parameters: a=0970 nm, b=074 mm, and c (chain axis) = 0682 nm There are two chains per unit cell, which exist in an anti parallel arrangement

X-Ray and Electron Diffraction Study of Poly(p-dioxanone)

Poly(lactide) swelling and melting behavior in supercritical carbon dioxide and post-venting porous material.

Trichlorophenylsilane (TCP) was hydrolyzed in an toluene/water heterogeneous solvent system, and a low molecular weight hydrolysate with simple structure was isolated from the aqueous solution while a high molecular weight hydrolysate with complicated structure was isolated from the toluene layer. When this hydrolysis was conducted strictly at 0°C, the primary hydrolysate consisting mainly of phenylsilanetriol (PST) could be crystallized out from the aqueous layer. When the low molecular weight hydrolysate obtained from the aqueous layer was subjected to the KOH-catalyzed polycondensation in refluxing toluene, poly(phenylsilsesquioxane) (PPQS) with a highly ordered ladder structure could be obtained. Its molecular weight increased with decreasing molecular weight of the initial hydrolysate, and its silanol content oppositely decreased with it. Since this polycondensation proceeded stepwise, it has been considered that intramolecular cyclization is favored in the first condensation of the low molecular weight hydrolysate and that the resultant higher oligomers are then connected into high polymer with ladder structure by the silanol coupling. The molecular weight of PPQS finally obtained reached 120 kDa.

/pdf/a-new-formation-process-of-poly-phenylsilsesquioxane-in-the-4sy54syr1e.pdf

A New Formation Process of Poly(phenylsilsesquioxane) in the Hydrolytic Polycondensation of Trichlorophenylsilane. Isolation of Low Molecular Weight Hydrolysates to Form High Molecular Weight Polymers at Mild Reaction Conditions

Strengthening of hydrogels made from enantiomeric block copolymers of polylactide (PLA) and poly(ethylene glycol) (PEG) by the chain extending Diels–Alder reaction at the hydrophilic PEG terminals

A tetracyclo(phenylsilsesquioxane) (T4) was first synthesized by the oligomerization of the low molecular weight hydrolysate of trichlorophenylsilane (TCP) by catalysis of the weak base, NaHCO 3 . followed by KOH-catalyzed polycondensation in toluene to form poly(phenylsilsesquioxane) (PPQS). The rate of polycondensation of T4 was much slower than that of direct polycondensation of the TCP hydrolysate under identical conditions. The molecular weight of the former product (M n =35800) was significantly lower than that of the latter product (M n =110000). X-Ray scatterings of the PPQS prepared by both processes were slightly different, probably due to the difference in structural regularity or branched structure. These data suggest that the polycondensations of T4 and the TCP hydrolysate should be driven through different reaction mechanisms, although the formation of the double strand ladder chain in the produced PPQS should be common to both.

/pdf/synthesis-and-polycondensation-of-a-cyclic-oligo-4wjiu3bmrs.pdf

Yoshiharu Kimura

Papers

X-Ray and Electron Diffraction Study of Poly(p-dioxanone)

Poly(lactide) swelling and melting behavior in supercritical carbon dioxide and post-venting porous material.

A New Formation Process of Poly(phenylsilsesquioxane) in the Hydrolytic Polycondensation of Trichlorophenylsilane. Isolation of Low Molecular Weight Hydrolysates to Form High Molecular Weight Polymers at Mild Reaction Conditions

Strengthening of hydrogels made from enantiomeric block copolymers of polylactide (PLA) and poly(ethylene glycol) (PEG) by the chain extending Diels–Alder reaction at the hydrophilic PEG terminals

Synthesis and polycondensation of a cyclic oligo(phenylsilsesquioxane) as a model reaction for the formation of poly(silsesquioxane) ladder polymer