Thermally Stable Electrospun Fiber Composites for Shrinkage Control
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Solution Overview
Problem
Electrospun materials used in medical applications are unstable and undergo significant structural and thermal changes due to crystallization and residual stresses, leading to distortions in fiber topography and mechanical properties.
Innovation Solution
A thermally stable electrospun material is created by combining two independent fiber populations, one thermally unstable and one thermally stable, which are co-mingled and distributed throughout the structure, maintaining physical and mechanical properties under thermal or mechanical stress without additional processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If electrospun materials are produced using rapid whipping instability to achieve high elongation ratio and fine fiber diameter, then fiber formation occurs rapidly with enhanced surface area to volume ratio, but residual stresses are generated and thermal stability is compromised leading to shrinkage and distortion
Solution Approach 1:
The patent applies composite materials by combining thermally unstable electrospun polymer fibers with thermally stable crosslinked polymer fibers to create a composite fibrous assembly. The thermally stable fibers act as a structural framework that prevents shrinkage and distortion of the thermally unstable fibers when exposed to physiological temperatures, thereby resolving the thermal stability issue while maintaining the fine fiber diameter and high surface area to volume ratio achieved through rapid whipping instability
Solution Approach 2:
The patent applies preliminary anti-action by pre-forming a thermally stable crosslinked fiber network before exposing the material to physiological temperatures. This pre-established stable structure counteracts the thermal shrinkage and distortion forces that would otherwise affect the thermally unstable electrospun fibers, preventing the harmful effects before they can manifest
2Stability of the object's composition
If layered constructs or cross-linked approaches are used to improve thermal stability, then structural stability is enhanced, but production complexity increases due to specialized equipment and additional processing
Solution Approach 1:
The patent merges the formation of thermally unstable electrospun fibers and thermally stable crosslinked fibers into a single simultaneous electrospinning process. Both fiber types are deposited together to form an intermingled fibrous assembly, eliminating the need for separate processing steps, specialized equipment, and complex multi-layer construction procedures that would otherwise be required
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The combined fiber populations provide thermal stability and minimize macroscopic changes, ensuring the material retains desirable characteristics like handling properties and morphology, even under heat exposure.
Implementation Method 1
the electrospinning method, using an electrical charge to draw very fine, typically on the micro or nano scale, fibers from a liquid
Implementation Method 2
By applying a critical voltage to overcome the surface tension of the polymer solution
Implementation Method 3
fiber formation occurs on the order of milliseconds due to the rapid evaporation of the solvent
Implementation Method 4
a rapid whipping instability, or fiber jet, is formed moving at approximately 10 m/s from the orifice to a distanced collector or substrate
Implementation Method 5
polymer crystallization can occur, distorting fiber topography, pore size, inducing shrinkage and altering mechanical properties
Implementation Method 6
at temperatures of 37° C., shrinkage as high as 20% has been observed
Data Source
AI summary
Thermally stable absorbable fiber populations, i.e. fiber populations that do not undergo thermally induced crystallization, can be intermixed with thermally unstable fibers to yield a stabilizing effect without altering morphological properties of a fiber system. Via this, one may minimize thermally induced shrinkage and maintain physical properties of electrospun materials in the as-formed state.