Date Approved

9-28-2023

Embargo Period

9-29-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biomedical Engineering

Department

Biomedical Engineering

College

Rowan-Virtua School of Translational Biomedical Engineering & Sciences

Advisor

Vince Beachley, Ph.D.

Committee Member 1

Mark E. Byrne, Ph.D.

Committee Member 2

Martin Haase, Ph.D.

Committee Member 3

Joseph Stanzione, Ph.D.

Committee Member 4

Sebastian Vega, Ph.D.

Keywords

Controlled Release, Drug Delivery, Electrospinning, Nanofiber, Track Spinning, Zone-Drawing

Subject(s)

Nanofibers--Processing

Disciplines

Biomedical Engineering and Bioengineering

Abstract

Electrospun nanofibers hold potential for a wide range of commercial and scientific applications; however, their properties must be optimized through post-processing treatments to achieve optimal performance. This dissertation investigates the effects of annealing and laser zone-drawing on electrospun nanofiber properties. Annealing polycaprolactone nanofibers at 70°C results in the highest rate of crystallization and molecular alignment, impacting long-term stability and mechanical properties. A multivariate linear model incorporating crystallinity and molecular alignment predicts the material properties resulting from annealing under different conditions. Laser zone-drawing experiments reveal that polylactide fiber thinning under laser irradiation primarily occurs due to drawing rather than ablation. Steady-state temperature, near the melt temperature of the polymer, is reached in the irradiated region of the fibers to lower the viscosity of the material and enable zone-drawing. Laser mediated zone drawing decreases and homogenizes fiber diameters. Finite element modeling of the heating and cooling kinetics shows that the smallest fibers reach 90% of their steady-state temperature for a particular laser power density in milliseconds, enabling precise control over fiber temperature and drawing processes to enhance macromolecular alignment and fiber mechanics.

This research provides insights into the effects of heat treatment and laser zone-drawing on electrospun polymer nanofibers, laying the foundation for future work investigating this processing technology and developing continuous manufacturing processes.

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