WITHDRAWN: PLA Stereocomplexes: A Decade of Progress

Conformational Footprint in Hydrolysis-Induced Nanofibrillation and Crystallization of Poly(lactic acid)

“…The design and further development of biodegradable aliphatic polyesters, such as poly­(lactic acid) (PLA), provide the essential cornerstone for advances in biomedical fields ranging from drug delivery devices to pharmacy and tissue engineering, as well as for the paradigmatic shift from petroleum-based to biobased packaging. − Critical to the applications of PLA-based biomaterials is the control of in vitro and in vivo degradation, both of which arouse the involvement of water. − Therefore, hydrolysis induced by water penetration and diffusion has been generally recognized as the main driving force for PLA degradation. − This inspires the rational design of usage-adaptive degradation properties, which is academically and commercially attractive to prompt a broader range of applications for PLA. − Available approaches to tailor the hydrolytic degradation of PLA include (1) generation of hydrophilic surfaces by grafting, − copolymerization, and cross-linking, − addition of hydrophilic fillers or polymers, , and creation of porous structures, , (2) facilitation of hydrolytic attack by incorporation of specialized proteinase, − and (3) control of the activation energy for hydrolysis by using nanosized particles . These methods, in essence, are associated with the design of molecular architectures and structural features that render the ability to interact with surrounding water molecules in a well-defined and controlled manner. − In contrast to the numerous attempts made to tailor the hydrolytic behavior of PLA, quite limited progress can be traced in understanding the fundamental mechanisms for hydrolysis-triggered fundamental structural transformation, particularly in the long-term. − …”

Synthesis of an Efficient Processing Modifier Silica-g-poly(lactic acid)/poly(propylene carbonate) and Its Behavior for Poly(lactic acid)/Poly(propylene carbonate) Blends

“…Poly­(lactic acid) (PLA) is one of the most promising biodegradable polymer materials; it comes from nature and returns to nature. , Because of some excellent properties such as good biocompatibility, mechanical strength, and excellent transparency, it has been widely used in scaffold fabrication, , stretch-blown bottles, tissue regeneration, and so on. However, it still has some fatal flaws such as low crystallization rate, high brittleness, low melt strength, and relatively high permeability toward gases and vapor, which still limit its use in the field of daily necessities such as packaging and plastic bags. − In recent years, researchers mainly use methods such as blending PLA with other polymers, , adding a nucleation agent, , forming a stereogenic complex structure between PLLA and PDLA, − and so on to improve the toughness and crystallinity of PLA, while there are still some problems, such as the bad compatibility of the blends, the adverse influence of nucleating agent on the toughness of crystalline PLA, and the quite harsh condition of forming PLLA/PDLA stereocomplex, all of which are very urgent to be solved.…”