Biocompatible Porous Constructs With Silicone-Coated Open Cells
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Solution Overview
Problem
Existing polyurethane foams are limited in mechanical, chemical, and structural properties, making them unsuitable for various applications, and alternative foams like open celled polyolefin and silicone foams lack sufficient microstructural variety and mechanical properties.
Innovation Solution
Developing biocompatible, open or semi-open celled constructs with controlled pore size, porosity, and interconnectivity using a polyurethane matrix coated with a conformal biocompatible layer, such as silicone, optionally enhanced with hydrophilic coatings, to create structures suitable for medical applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If polyurethane foams are used to achieve open celled structure with pore sizes of 25-2500 um, then the microstructure can be controlled within 20-140 ppi, but the chemical properties are limited and the material performs poorly in acid or base contacting applications due to hydrolytic attack susceptibility of ester based polyols
Solution Approach 1:
The patent applies composite materials by combining polyurethane foam with silicone coating to create a biocompatible construct. The silicone layer protects the polyurethane matrix from chemical degradation while maintaining the desired porous microstructure, thus resolving the contradiction between achieving controlled microstructure and ensuring chemical stability in harsh environments.
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating silicone (a chemically stable material) into the polyurethane foam structure. This parameter change enhances the chemical resistance of the overall construct while preserving the mechanical and structural properties provided by the polyurethane matrix.
2Shape
If polyurethane foams are used to achieve open celled structure, then the pore sizes can range from 25 to 2500 um, but the thermal stability is limited to not exceeding 150° C. operating temperature
Solution Approach 1:
The silicone-coated polyurethane foam construct utilizes composite materials where the silicone layer provides enhanced thermal stability. Silicone can withstand higher temperatures than polyurethane, thus the composite structure raises the overall thermal stability limit while maintaining the beneficial open-celled microstructure of the polyurethane core.
3Reliability
If non-polyurethane foams like open celled polyolefin or silicone foams are used to achieve different microstructures, then the material properties can be varied, but the microstructure is highly limited in its variety of pore sizes, interconnections per pore, structure of the outer skin, porosity, size of interconnections, and size of supporting struts
Solution Approach 1:
The patent uses composite materials (polyurethane foam core with silicone coating) to combine the microstructural versatility of polyurethane foam manufacturing with the material properties of silicone. This allows achieving a wide variety of pore sizes, interconnections, and skin structures while ensuring the chemical and thermal stability provided by silicone.
4Strength
If silicone foams are used to achieve high elongation at break of over 1200%, then the material has excellent flexibility, but the microstructure is highly limited and the properties are substantially lower than what would be expected for the raw material itself when foamed
Solution Approach 1:
The composite structure combines the excellent elongation properties of silicone with the superior microstructural control capabilities of polyurethane foam technology. The silicone provides the flexibility and high elongation at break, while the polyurethane foam matrix allows for precise control of pore size, interconnectivity, and overall microstructure that would be difficult to achieve in silicone foam alone.
Data Source
AI summary
Methods and materials used for production of constructs having a porous open or semi-open celled structure. Constructs may include a porous matrix as a base and a biocompatible conformal coating thereon.