Factors affecting aliphatic polymer degradation

The degradation rate of bioresorbable polymers depends on their intrinsic properties such as reactivity, hydrophilicity, molecular weight, degree of crystallinity, and glass transition temperature. However, other external factors such as the degradation media, sterilisation and sample size also play a role in the degree of degradation. 

There have been many studies in which the interplay between aliphatic polyester composition and degradation is considered. Particular 

Media pH can affect polymer degradation, either directly, by altering the polymer chemistry involved during degradation, or indirectly, by interacting with degradation products and affecting consequent kinetics. 

6 Half-life of PLA and PGA homopolymers and copolymers (from Middleton and Tipton ). 

Chu found there was a greater loss in the mechanical properties of PGA sutures in buffered than nnbnffered solutions. Similarly, the presence of buffer ions increases the degradation rate of poly(a-hydroxy acid) copolymers as a result of the enhanced removal of degradation products through neutralisation 

---

Factors which can affect the biodegradation of these polymers have been gradually identified. However, many findings are still controversial. This chapter has tried to clarify the situation on the basis of a discussion of qualitative work. Quantitative approaches must now be developed if one really wants to control the fate of aliphatic polyesters during degradation. 

---