Customizing the hydrolytic degradation rate of stereocomplex PLA through different PDLA architectures

Area of Science:

• Polymer Science
• Materials Science
• Biomaterials Engineering

Background:

• Poly(L-lactide) (PLLA) is a widely used biodegradable polymer.
• Controlling the degradation rate and products of PLLA is crucial for its applications.
• Stereocomplexation offers a method to modify PLLA properties.

Purpose of the Study:

• To investigate how different architectures and end-groups of D-lactic acid (D-LA) oligomers affect PLLA stereocomplexation.
• To determine the influence of these D-LA oligomers on the hydrolytic degradation rate and product profiles of PLLA.
• To establish methods for customizing PLLA degradation through stereocomplexation.

Main Methods:

• Preparation of nine PLLA/D-LA oligomer blends with varying compositions (30-50 wt% D-LA).
• Fractional factorial experimental design to study the influence of temperature, time, and D-LA oligomer characteristics.
• Analysis of hydrolytic degradation, mass loss, molar mass changes, and degradation product release.

Main Results:

• Stereocomplexes with star-shaped D-LA oligomers (four alcoholic end-groups) showed slow degradation and low product release.
• Linear D-LA oligomers resulted in similar mass loss but higher concentrations of acidic degradation products.
• Increased stereocomplexation (linear or four alcoholic end-groups) slowed mass loss, while carboxylic end-groups accelerated it.
• Higher numbers of alcoholic end-groups (six) decreased stereocomplexation and increased degradation rate.
• D-LA oligomer architecture and end-groups were shown to customize the degree of stereocomplexation and degradation rate.

Conclusions:

• The architecture and end-group functionality of D-LA oligomers are critical determinants of PLLA stereocomplexation.
• These tailored stereocomplexes allow for controlled modulation of PLLA's hydrolytic degradation rate and product profiles.
• This study provides a pathway for designing advanced biodegradable PLLA materials with predictable degradation behaviors.