Characterization of Sequence Distributions in Random and Semi-Random Copolymers

Area of Science:

• Polymer Chemistry
• Materials Science
• Analytical Chemistry

Background:

• Poly(lactic-co-glycolic acid) (PLGA) is a widely used biodegradable polyester.
• Controlling the sequence distribution in PLGA is crucial for tuning its degradation rate and mechanical properties.
• Existing methods for sequence analysis in PLGA are limited, especially for semirandom copolymers.

Purpose of the Study:

• To develop a novel strategy for analyzing and distinguishing sequence distributions in random and semirandom PLGA copolymers.
• To enable coarse-grained sequence control in PLGA synthesis.
• To provide a scalable platform for tuning and characterizing sequence distributions in degradable polyesters.

Main Methods:

• Synthesis of semirandom copolymers using a parallel-successive (P-S) approach.
• Selective digestion of copolymers at cleavable olefin-containing monomer units.
• Analysis of fragment distributions using Nuclear Magnetic Resonance (NMR), Size Exclusion Chromatography (SEC), and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS).
• Monte Carlo simulations to model copolymerizations and predict fragment distributions.

Main Results:

• The P-S approach enables coarse-grained sequence control in PLGA synthesis.
• Selective digestion and subsequent analysis accurately reflect the microstructural arrangement of monomer units.
• Experimental and simulated results show distinct fragment distributions for P-S copolymers compared to random copolymers, with P-S exhibiting broader or bimodal distributions.
• The method successfully distinguishes between random and semirandom PLGA sequences.

Conclusions:

• The developed strategy provides a robust and scalable method for analyzing sequence distributions in PLGA.
• This approach allows for the precise tuning and characterization of polymer microstructures.
• The findings have implications for designing advanced degradable polyesters with tailored properties for various applications.