The effects of temperature, feed ratio, and reaction time on the properties of copolymer PLA-PEG-PLA

Abstract

Triblock copolymers were polymerised by the ring-opening reaction of D,L-lactide in the presence of poly(ethylene glycol) (PEG), with number-average molecular weight (Mn) of 1500 and 2050 g/mol, using Sn(Oct)2 as a catalyst. The influences of the reaction time, the ratio of PEG and Poly(D,L-lactic acid) (PLA), and PEG types on structure and sol-gel phase transition of PLA-PEG-PLA triblock copolymers were investigated. Optimal polymerisation parameters were obtained, such as reaction time of 18 hours, a catalyst amount of 1.3%, and PEG/PLA ratio of 1/1.7, PEG (Mn=1500); the efficiency of the triblock synthesis was 42.3%. The properties of PLA-PEG-PLA copolymers were evaluated by analytical methods such as proton nuclear magnetic resonance H1NMR spectroscopy, gel permeation chromatography (GPC), and the sol-gel state transition at varying temperature. The results show that the triblock was successfully synthesised and its hydrogel had capability of the sol-gel state transition when the temperature changed. The PLA-PEG-PLA copolymer in aqueous solution is a thermo-sensitive hydrogel that can be used for drug and protein delivery systems or triblock denaturation applications for commercial purposes.

Design of Experiments Grants Mechanistic Insights into the Synthesis of Spermine-Containing PBAE Copolymers

“…To demonstrate how data science can be used to understand and facilitate complicated scientific questions such as the controlled synthesis of block copolymers for the encapsulation of RNA, we synthesized spermine- and oleylamine-modified PBAE-based copolymers using DoE to iterate over a variable space with reasonable ranges for synthesis parameters including temperature, reaction time, and the ratio of monomers, which influence the characteristics of the synthesized materials. , Spermine was chosen as a body-own polycation to enhance RNA encapsulation efficiency and oleylamine to introduce hydrophobicity into the resulting polyplexes to facilitate the endosomal escape, demonstrated by previous work from our group . As a readout, we selected the final composition of blocks in the resulting polymer and different results from the polymer size measurements.…”