Poly hydroxy acids

Figure 3 Chemical structure of poly(lactic-co-glycolic) acid polymer. The x component represents lactic acid and y component represents glycolic acid. For other poly(hydroxy acids), the side-chain methyl group is replaced by other alkyl groups.

From Poly-hydroxy Alcohols.—4. Poly-hydroxy alcohols by oxidation, yield poly-hydroxy acids. In this case, of course, only primary alcohol groups, ( —CH2OH), can yield carboxyl and these groups must, necessarily, be at the end of the carbon chain. The oxidation must be mild so that only one alcoholic group shall be affected. 

As the poly-hydroxy aldehydes, or sugars, are the intermediate products in this reaction it is practically the same synthesis if we start with the sugars and oxidize them to the corresponding poly-hydroxy acids. 

This is an important reaction for converting the poly-hydroxy acids into simpler acids. 

When more than one hydroxyl group is substituted in the ring of an aromatic acid there will result poly-phenol acids i.e., poly-hydroxy acids. The poly-hydroxy benzoic acids, which include the most important members, bear the same relation to benzoic acid that the ordinary poly-phenols, e.g., pyrocatechinol, resorcinol, pyrogallol, etc. (p. 617), do to benzene. They may also be considered as carboxyl substitution products of the poly-phenols. 

The adverse environments experienced during high temperature processing are exemplified by studies on PS blends with PIB [La Mantia and NociUa, 1987] and with PE [Komova et al., 1991 1992], of PE/PP blends [La Mantia et al., 1985], and of poly(hydroxy acids) blends with poly(hydroxybutyrates) [Gogolewski et al.,... 

Aliphatic polyesters may be classified into two groups, depending on the bond constitution of the monomCTs poly(hydroxy acid)s i.e. polyhydroxyalkanoates (PHAs)) and polyfalkylene dicarboxylate)s [68]. The former are polymers of hydroxy acids (a, p,...(i)-hydroxy acids), obtained by ring-opening polymerization or polycondensation reactions. The latter are S3uithesized by the polycondensation reaction of diols with dicarboxylic acids. Aldonic and aldaric acids can be used to prepare both groups of polyesters. 

Table 3 Masses of prominent ions observed in SSIMS of poly (hydroxy acids) commonly used as bioerodible systems. Weak ion intensities are noted by (w), - denotes ions too weak to be observed... 

In poly (hydroxy acids) analysed by SSIMS a diagnostic series of ions exist in the positive and negative ion spectra which reflect the polymer structure. These are provided in Table 3 for the three pohuners mentioned above and poly (caprolactone) (PCL). These ions result from scission of the polymer either at the ester linkage or in sites adjacent to it. Assignments of structures to some these ions are given below based on the discussion of Shard et al. (1996). 

K. luni, and M. Nakano, Poly(hydroxy acids) in drug delivery, Crit. Rev. Ther. Drug Carrier Syst, 3 (3), 209-232,1987. 

Poly(hydroxy acid)s are an important class of degradable polymers for biomedical applications due to their biocompatibility and physiologically tolerable degradation products 886302. Poly(L-lactic acid) or poly(L-lactide) (PLLA) has been used as a biomaterial for tissue engineering, bone fracture fixation and controlled drug delivery... 

Eco-Friendly Biocatalytic Synthesis of Poly(Hydroxy Acids)... 

Lipase-Catalyzed Synthesis of Poly(Hydroxy Acid) Esters... 

Vert, M. and Guerin, P. (1991) Biodegradable aliphatic polyesters of the poly(hydroxy acid)-type for temporary therapeutic applications, in M.A. Barbosa (ed.). Biomaterial Degradation Fundamental Aspects and Related Clinical Phenomena, Elsevier, Amsterdam, pp. 35-51. 

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