Physics-Based Models of Extraction Kinetics in Solvent-Swollen Polymers: Using Non-Exhaustive Extractions to Estimate...

Area of Science:

• Materials Science and Engineering
• Biomedical Engineering
• Chemical Engineering

Background:

• Leachables from polymeric medical devices pose potential health risks through in vivo migration.
• Accurate estimation of the initial leachable amount (M0) is crucial for physics-based mass-transport models.
• Exhaustive extraction testing for M0 determination can be impractical due to kinetic or thermodynamic limitations.

Purpose of the Study:

• To develop a novel free-volume model for estimating M0 from non-exhaustive extractions.
• To incorporate solvent-swelling effects on solute diffusivity (D) within the polymer matrix.
• To propose a limiting value for the polymer/solvent partition coefficient (K) for improved M0 prediction.

Main Methods:

• Developed a free-volume model integrating solvent-swelling effects on solute diffusivity (D).
• Analyzed polymer/solvent partition coefficients to establish a limiting value for K.
• Coupled the developed model with a mass-transport equation to predict M0.

Main Results:

• The model demonstrated order-of-magnitude accuracy in predicting both solute diffusivity (D) and initial leachable amount (M0).
• Validation against experimental data confirmed the model's predictive capabilities.
• Predicted M0 values, when used in in vivo exposure models, yielded results comparable to those using a priori M0 knowledge.

Conclusions:

• Non-exhaustive extractions can be effectively utilized to infer total extractable quantities from polymeric medical devices.
• The developed free-volume model provides a practical and accurate method for estimating M0, applicable to rubbery polymers and hydrophobic systems.
• This approach enables conservative estimation of patient exposure to leachables, enhancing medical device safety assessments.