Poly (L-lactic acid) is known to be highly crystalline and not to be completely resorbed over periods of time as long as 143 weeks. Explain how the presence of crystalline regions in this polyester could contribute to its exceptionally long resorption time.

How could you tune?

Question: Poly (L-lactic acid) is known to be highly crystalline and not to be completely resorbed over periods of time as long as 143 weeks. Explain how the presence of crystalline regions in this polyester could contribute to its exceptionally long resorption time.

How could you tune?

Answer:

Polyesters, like Poly (L-lactic acid), degrade due to hydrolysis. Therefore, water must be able to

enter the polymer network to cleave the ester bonds. The crystalline regions of the polymer are

highly ordered and stable, so water penetration into these crystalline regions will be limited.

With limited water penetration into the crystalline regions, the polymer backbone degrades at a

much slower than an amorphous polymer. This contributes to the exceptionally long resorption

time. Theoretically, you could tune the degradation rate by altering the amorphous and

crystalline regions of the polyesters. Three biomedical applications for this polymer would be

vascular stents, synthetic tissue scaffolds, and sutures where high mechanical strength,

toughness, and long degradation rates are required