# The Use of Monodisperse Poly(propylene glycol)‑8 as a Polymeric Additive: Effect on the Gelation Temperature and Rheological Properties of Pluronic Hydrogels

## TL;DR

This study shows how adding a specific polymer, PPG-8, improves the properties of Pluronic F127 hydrogels for better medical use.

## Contribution

The use of monodisperse PPG-8 as a cost-effective modifier to enhance Pluronic hydrogel properties is novel.

## Key findings

- Adding PPG-8 increased the gelation temperature of Pluronic F127 from 21 to 31 °C.
- PPG-8 increased the release of hydrophobic molecules from 20% to 60%.
- PPG-8 reduced the initial burst release of hydrophilic molecules from 81% to 56%.

## Abstract

Pluronic F127 is widely used for hydrogel preparation,
but its
low gelation temperature (21 °C at a concentration of 25 wt %)
and limited ability to deliver hydrophobic drugs hinder medical applications.
A standard approach to address these limitations involves combining
Pluronic F127 with other polydisperse polymers, further increasing
the system complexity. This study demonstrates the use of monodisperse
and high-purity poly­(propylene glycol)-8 (PPG-8), obtained via cost-effective
chromatographic purification, as a polymeric modifier. The effect
of PPG-8 addition to Pluronic F127, varying from 5 to 20 parts (w/w),
was assessed via the vial tilt method and oscillatory rheology. The
incorporation of PPG-8 increased the gelation temperature from 21
to 31 °C. The impact of PPG-8 addition on the release of small
hydrophilic and hydrophobic molecules was also studied. In the presence
of PPG-8, the cumulative release of a hydrophobic small molecule increased
from 20% to 60%. Contrastingly, the initial burst release of a small
hydrophilic molecule was reduced from 81% to 56% in the first 10 min.
These findings showcase the use of high-purity modifiers such as PPG-8
to fine-tune the properties of Pluronic hydrogels, enabling more reproducible
formulations for potential clinical use.