Effect of Homopolymer Length on Relaxation and Structure of Complex Coacervate Core Hydrogel

Complex coacervate core hydrogels(C3Hs) are formed by mixing of the ABA triblock copolyelectrolyte solution and oppositely charged polyelectrolytes solution, resulting in the complex coacervate cores bridged by hydrophilic B blocks. C3Hs has gained attention in the field of sustained release due to its ability to encapsulate charged substances such as DNA, mRNA, and proteins. In this study, the relaxation and structure of C3Hs is investigated as a function of polymer architecture and homopolyelectrolyte length. We observed that the core size and the core-to-core distance remain nearly identical, but the relaxation time is highly dependent on the homopolymer length. We believe that the hydrogel relaxation time is proportional to the chain release of triblock copolymer from the coacervate cores, and this dynamic behavior is directly related to the length of the homopolymer such as charge neutralization and coacervate viscosity. The discussions are based on the current study of chain dynamics in complex coacervates and self-assembled hydrogels using ABA-type triblock copolymers.