Paper Number
GG50 

Session
Rheology of Gels, Glasses and Jammed Systems

Title
Understanding the temperature-dependent rheological and structural transitions in ABA/BAB polymer blends

Presentation Date and Time
October 12, 2022 (Wednesday) 5:05

Track / Room
Track 3 / Sheraton 5

Authors (Click on name to view author profile)

1. White, Joanna M. (University of Minnesota, Chemical Engineering and Materials Science)
2. Calabrese, Michelle A. (University of Minnesota, Chemical Engineering and Materials Science)

Author and Affiliation Lines (in printed abstract book)
Joanna M. White and Michelle A. Calabrese
Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455

Speaker / Presenter 
White, Joanna M.

Keywords
experimental methods; biomaterials; gels; polymer blends; polymer solutions

Text of Abstract
Poloxamers are ABA triblock polymers composed of poly(ethylene oxide) (PEO) endblocks (A) and a poly(propylene oxide) (PPO) midblock (B) that have attracted much attention as drug-delivery vehicles due to their thermoresponsive assembly and gelation near body temperature. In relatively low concentrations, Poloxamer 407 (P407) assembles into disordered spherical micelles at room temperature that can be used to encapsulate hydrophobic drugs. Near body temperature, these formulations undergo a solution-to-gel transition as the micelles order into cubic packings. While such gels have promise for targeted delivery, much of the applicability is currently limited due to low dynamic moduli upon addition of drugs. Here, we show that addition of BAB reverse poloxamers (RPs) can enhance the moduli of P407 gels and alter the gelation temperature, allowing for tunability of formulations for desired applications. Further, varying the RP hydrophobic PPO block fraction and molecular weight results in differing incorporation mechanisms into P407-systems. For example, RPs with very high PPO fractions form co-micelles with P407 while RPs with lower PPO fractions form bridges that serve as physical crosslinks between P407 micelles. In addition to affecting the moduli and gelation temperatures, these differences in structure can alter drug distribution, bioadhesion, and syringeability. Understanding these incorporation methods can lead to the development of drug-loaded formulations that can easily be administered as a liquid at room temperature and then rapidly form a gel with desired moduli and bioadhesive properties at body temperature.