Poly(l-lactide) is a polymer synthesized by the ring-opening polymerization of l-lactide or polycondensation of l-lactic acid.

Poly(L-lactide) is a polymorphic material which has three forms of crystalline structure: α, β and γ. Poly(L-lactide) was found that a polymorphic material with a different form of crystalline structure exhibits different physical properties. Poly(L-lactide) has a low crystallization rate, compared to other thermoplastics, and it is rather easy to define the processing conditions to obtain Poly(L-lactide) products with a wide range of degree of crystallinity.

Poly(L-lactide) is a biodegradable polymer for medical device and pharmaceutical applications. Poly(L-lactide) is used to fabricate resorbable medical devices that degrade over months in physiological conditions. Due to their history, polylactides are one of the easiest and most affordable biodegradable polymers for medical devices.

Fig 1. Chemical structure formula of Poly(L-lactide)

Poly(l-lactide)(PLLA,C6H8O4) is a polymer synthesized by the ring-opening polymerization of l-lactide or polycondensation of l-lactic acid.

Poly(L-lactide) came into focus because of its biodegradability, biocompatibility and production from renewable resources. Although Poly(L-lactide) is a brittle polymer with high production cost, it successfully found the way to replace commodity polymers in biomedicine, packaging and other fields. Poly(L-lactide) is a polymorphic material which has three forms of crystalline structure: α, β and γ[1]. Poly(L-lactide) was found that a polymorphic material with a different form of crystalline structure exhibits different physical properties[2]. Poly(L-lactide) has a low crystallization rate, compared to other thermoplastics, and it is rather easy to define the processing conditions to obtain Poly(L-lactide) products with a wide range of degree of crystallinity[3]. With different crystalline morphologies and different degrees of crystallinity, various product properties can be obtained. Many scientists have been discussing the crystallization behaviour of Poly(L-lactide), but just a few of them have investigated the crystallization kinetics, especially taking into account the influence of a filler on the crystallization kinetics of Poly(L-lactide).The crystallite size of Poly(L-lactide) decreases with increasing cooling rates and the conditions for the growth of the lamellar structure is more suitable at the lower cooling rate[4].

Poly(L-lactide) is a biodegradable polymer for medical device and pharmaceutical applications. It is used to fabricate resorbable medical devices that degrade over months in physiological conditions. Due to their history, polylactides are one of the easiest and most affordable biodegradable polymers for medical devices.

References

[1] X. Jiang, Y. Luo, X. Tian, D. Huang, N. Reddy, Y. Yang Chemical structure of poly(lactic acid) R. Auras, L.-T. Lim, S.E.M. Selke, H. Tsuji (Eds.), Poly(Lactic Acid): Synthesis, Structures, Properties, Processing and Applications, John Wiley & Sons Inc., New Jersey (2010), pp. 69-80
[2] W. Kai, B. Zhu, Y. He, Y. Inoue Crystallization of poly(butylene adipate) in the presence of nucleating agents J. Polym. Sci. B, 43 (2005), pp. 2340-2351.
[3] M.L. Di Lorenzo. The crystallization and melting process of poly(l-lactide) Macromol. Symp., 234 (2006), pp. 176-183.
[4] Yang J L, Zhao T, Cui J J, et al. Nonisothermal crystallization behavior of the poly(ethylene glycol) block in poly(L-lactide)-poly(ethylene glycol) diblock copolymers: Effect of the poly(L-lactide) block length[J]. 2010, 44(22):3215-3226.