Effect of carboxyl end groups on hydrolysis of polyglycolic acid

Abstract

Dye interaction analysis in hexafluoroisopropanol was used to determine end carboxyl groups in polyglycolic acid (PGA). The rate of heterogeneous hydrolysis of purified PGA in water at 37°C shows a first‐order dependence on carboxyl end group concentration at levels above 12 meq/kg. Reaction of molten PGA with a tetraarylorthocarbonate or a triarylketenimine gave end‐capped PGA with carboxyl levels as low as 1 meq/kg. These samples were somewhat more resistant to hydrolysis than untreated PGA despite an increased initial rate at the lower carboxyl levels.

In vitro degradation behavior of a novel bioresorbable composite material based on PLA and a soluble CaP glass

“…This behaviour could be attributed to the buffering effect caused by the degradation products of the phosphate glass, which even if not basic, are less acidic than the degradation products of the PLA [12]. It is well known that the degradation mechanism for the PLA is a bulk mechanism autocatalysed by carboxyl end groups formed by chain cleavage [30]. Therefore, the degradation products released from the glass particles could act as a buffering agent, hindering the autocatalytic process and hence, levelling off the weight loss and the M w loss of the composite.…”

Migration resistant polymeric plasticizer for poly(vinyl chloride)

“…The catalytic effect of carboxylic acid end-groups on ester-hydrolysis and the hydrolysis-inhibiting results of end-capping has been shown in many studies on polyester hydrolysis. [32][33][34][35][36][37] Reduced rate of chain-scission by partial ethoxylation of poly (caprolactone) was seen by Pitt and Gu in 1987 34 and improved hydrolytic stability was obtained when the amount of carboxylic end-groups was reduced in a poly(butylene terephthalate) polymer. 35 Increased hydrolysis rate of star-shaped PLA 36 was seen when the arms were functionalized with carboxylic end-groups compared to À ÀOH, À ÀCl, and À ÀNH 2 end-groups.…”

Development of a Biodegradable Composite Scaffold for Bone Tissue Engineering: Physicochemical, Topographical, Mechanical, Degradation, and Biological Properties

“…In general, the degradation of PLA depends on several factors, which include its crystallinity, molecular weight, dimensions, composition, and the pH of the surrounding medium. Nevertheless, in spite of the influence these factors may have on the degradation of PLA, it is well known that the degradation mechanism of this polymer is a bulk mechanism autocatalyzed by carboxyl end groups formed by chain cleavage [25,26].…”