Crystallinity Dependence of PLLA Hydrophilic Modification during Alkali Hydrolysis

Abstract

Poly(L-lactic acid) (PLLA) has been extensively used in tissue engineering, in which its surface hydrophilicity plays an important role. In this work, an efficient and green strategy has been developed to tailor surface hydrophilicity via alkali hydrolysis. On one hand, the ester bond in PLLA has been cleaved and generates carboxyl and hydroxyl groups, both of which are beneficial to the improvement of hydrophilicity. On the other hand, the degradation of PLLA increases the roughness on the film surface. The resultant surface wettability of PLLA exhibits crucial dependence on its crystallinity. In the specimen with high crystallinity, the local enrichment of terminal carboxyl and hydroxyl groups in amorphous regions accelerates the degradation of ester group, producing more hydrophilic groups and slit valleys on film surface. The enhanced contact between PLLA and water in aqueous solution (i.e., the Wenzel state) contributes to the synergistic effect between generated hydrophilic groups and surface roughness, facilitating further degradation. Consequently, the hydrophilicity has been improved significantly in the high crystalline case. On the contrary, the competition effect between them leads to the failure of this strategy in the case of low crystallinity.

Functional polymeric molecules for performing autonomous synthesis of particles with core–shell structures and customizable shapes

“…The polymeric chains of PLA, PLGA, and PS are mostly hydrophobic. At high pH, the PLA or PLGA molecules undergo hydrolysis 44,45 and are broken down into smaller molecules. Hydrolysis generates carboxylic acid groups as the terminated groups of the smaller PLA or PLGA molecules.…”

Progress of biodegradable polymer application in cardiac occluders

“…59,[61][62][63][64][65][66] Studies have shown that the hydrophobicity and acidic products of PLLA might affect cell adhesion. 143,157 Nevertheless, when used as the fabric component for Absnow and modified Amplazter occluders, it demonstrated a satisfactory endothelialization process and tolerable inflammatory response, proving its feasibility as a fabric material. [61][62][63][64]68,69,71,72 Various methods, such as surface treatment, chemical crosslinking, and blending with other materials can modify the mechanical properties, hydrophobicity, and degradation time of PLLA, making it one of the most promising candidates materials for both skeleton and fabric of bioabsorbable cardiac occluders.…”

“…To keep the mechanical strength of the occluder for its functioning, additional locking systems are required when PLLA is used as the skeleton material in both PLLA/PDLLA and Absnow occluders 59,61–66 . Studies have shown that the hydrophobicity and acidic products of PLLA might affect cell adhesion 143,157 . Nevertheless, when used as the fabric component for Absnow and modified Amplazter occluders, it demonstrated a satisfactory endothelialization process and tolerable inflammatory response, proving its feasibility as a fabric material 61–64,68,69,71,72 .…”

Effects of Adhesive or Non-adhesive Protein-immobilized Bioactive（Lactic Acid-ε-caprolactone）Films on Mouse Osteoblast-like Cells

“…There are many methods for surface modification of hydrophobic PLA, PCL, and PLCL. The most common are plasma etching, physical coating, and hydrolysis to physically and chemically immobilize biological substances, such as proteins and polysaccharides (29) .…”