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Updated: Aug 24, 2025
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Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels
Published on: September 8, 2016
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Phenol release from pNIPAM hydrogels: scaling molecular dynamics simulations with dynamical density functional theory
H A Pérez-Ramírez1, A Moncho-Jordá2, G Odriozola1
1Área de Física de Procesos Irreversibles, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Azcapotzalco, Avenida San Pablo 180, 02200 Ciudad de México, Mexico. godriozo@azc.uam.mx.
Soft Matter
|October 24, 2022
Summary
We calculated the free energy of transfer for molecules like phenol and 5-FU in water-pNIPAM mixtures. Results show linear behavior with polymer concentration, aiding microgel release predictions.
Area of Science:
- Computational chemistry and materials science.
- Investigating molecular interactions in polymer solutions.
Background:
- Poly(N-isopropylacrylamide) (pNIPAM) exhibits a lower critical solution temperature (Tc), influencing its interaction with solutes.
- Understanding solute behavior in pNIPAM solutions is crucial for applications like drug delivery and microgel design.
Purpose of the Study:
- To compute the free energy of transfer (ΔGtrans) of phenol, methane, and 5-fluorouracil (5-FU) between water and water-pNIPAM mixtures.
- To investigate the effect of pNIPAM concentration (ϕp) and temperature on solute transfer.
- To provide essential data for predicting microgel release kinetics.
Main Methods:
- Employed molecular dynamic simulations (MD) to calculate solvation free energies.
- Utilized Bennett's acceptance ratio method for precise free energy of transfer computations.
- Calculated diffusion coefficients (D) for phenol in water-pNIPAM mixtures.
Main Results:
- Phenol and 5-FU consistently show negative ΔGtrans, indicating strong interaction with pNIPAM.
- Methane exhibits a temperature-dependent sign change in ΔGtrans relative to pNIPAM's Tc.
- ΔGtrans displayed linear dependence on pNIPAM concentration, contradicting some theoretical predictions.
- MD-derived data accurately predicted microgel release halftime.
Conclusions:
- Solute transfer in water-pNIPAM mixtures is predictable and linearly dependent on polymer concentration.
- The study provides a robust method for calculating transfer free energies and diffusion coefficients.
- Findings are critical for the rational design and application of pNIPAM-based microgels.
