Anisotropic copoly(imide oxetane) coatings and articles of manufacture, copoly(imide oxetane)s containing pendant fluorocarbon moieties, oligomers and processes therefor
Inventors
Wohl, JR., Christopher J. • Connell, John W. • Siochi, Emilie J. • Smith, Jr., Joseph G.
Assignees
National Aeronautics and Space Administration NASA
Publication Number
US-11760738-B2
Publication Date
2023-09-19
Expiration Date
2031-11-01
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Abstract
Copoly(imide oxetane) materials are disclosed that can exhibit a low surface energy while possessing the mechanical, thermal, chemical and optical properties associated with polyimides. The copoly(imide oxetane)s are prepared using a minor amount of fluorinated oxetane-derived oligomer with sufficient fluorine-containing segments of the copoly(imide oxetane)s migrate to the exterior surface of the polymeric material to yield low surface energies. Thus the coatings and articles of manufacture made with the copoly(imide oxetane)s of this invention are characterized as having an anisotropic fluorine composition. The low surface energies can be achieved with very low content of fluorinated oxetane-derived oligomer. The copolymers of this invention can enhance the viability of polyimides for many applications and may be acceptable where homopolyimide materials have been unacceptable.
Core Innovation
The invention provides copoly(imide oxetane) materials that combine the mechanical, thermal, chemical, and optical properties of polyimides with low surface energy characteristics. These copolymers are prepared using a minor amount of an amino-terminated fluorinated oxetane-derived oligomer. The fluorine-containing segments migrate to the exterior surface of the material, resulting in coatings and articles having an anisotropic fluorine composition with low surface energies.
The problem addressed is the challenge in modifying high performance polymeric materials to exhibit low adhesion surface properties without degrading their essential bulk properties. Existing fluorinated polymers either cannot be tailored for surface features or suffer from poor adhesion or processing difficulties. Achieving low surface energy while maintaining the bulk properties of polyimides has been a significant unmet need.
By incorporating a very low content of fluorinated oxetane-derived oligomer (often below about 0.5 mass percent), the invention achieves a surface saturated with fluoro-groups, yielding a water contact angle greater than about 85°, often exceeding 90°. This enables tailoring of surface properties without compromising the physical performance of polyimides. The copoly(imide oxetane)s may be block or random copolymers and can be processed into coatings or shaped articles exhibiting anisotropic distribution of fluorine atoms concentrated near the surface.
Claims Coverage
The patent contains multiple independent claims covering copoly(amic acid oxetane) compositions, polymer composites containing these copolymers, and processes for synthesizing these materials, including their imidization to form copoly(imide oxetane)s.
Copoly(amic acid oxetane) structure
A copoly(amic acid oxetane) having a defined structure combining fluorine-containing oxetane-derived oligomers with polyamic acid segments, characterized by specific chemical formulas involving fluorinated oxetane oligomer units and diamines/dianhydrides.
Polymer composite with high water contact angle
A polymer composite comprising the copoly(amic acid oxetane) and a particulate filler, wherein the composite exhibits a water contact angle of at least 100°, indicating low surface energy.
Process for making copoly(amic acid oxetane)
A multi-step synthesis process involving: (a) reacting a defined fluorine-containing oxetane oligomer with an acyl reagent to form a nitro-terminated oligomer; (b) hydrogenating this nitro-terminated oligomer to form a diamine-terminated oligomer; and (c) reacting this diamine-terminated oligomer with dianhydrides and diamines (or prepolymers thereof) under condensation polymerization conditions to form the copoly(amic acid oxetane).
Process for imidization of copoly(amic acid oxetane)
A process for converting the copoly(amic acid oxetane) to copoly(imide oxetane) by subjecting it to imidization conditions.
Thermal imidization conditions
An embodiment where imidization is carried out by thermal ring closure at temperatures between about 150° C. and 400° C.
Chemical imidization conditions
An embodiment where imidization is conducted chemically in the presence of ring-closing catalysts such as pyridine, triethylamine, or acetic anhydride, at temperatures between −20° C. and 200° C.
Copoly(imide oxetane) made by the described process
A copoly(imide oxetane) polymer product produced by the process of imidizing the copoly(amic acid oxetane).
The claims collectively cover the novel copoly(amic acid oxetane) compositions containing fluorinated oxetane oligomers, composite materials with enhanced surface properties, and the synthesis and imidization processes to produce copoly(imide oxetane) polymers with low surface energy and maintained polyimide properties.
Stated Advantages
The copoly(imide oxetane)s achieve low surface energies with very small amounts of fluorinated oxetane oligomer, often below 0.5 mass percent.
They maintain the mechanical, thermal, chemical, and optical properties associated with polyimides while providing hydrophobic and low adhesion surface properties.
The surface fluorine concentration is anisotropic, concentrating at the outer surface to yield water contact angles greater than about 85°, often exceeding 90°.
The copolymers improve the viability of polyimide materials for applications where homopolyimide materials have been unacceptable.
The approach avoids degradation of bulk properties by limiting the fluorinated oligomer content, facilitating coating and article manufacturing.
Documented Applications
Coatings on various substrates such as metals, ceramics, glass, wood, paper, fibers, textiles, membranes, and polymer surfaces.
Articles of manufacture including molded, cast, extruded polymeric matrices exhibiting low surface energy.
Applications requiring passive surface fouling resistance such as marine biofouling, membrane fouling, insect adhesion on aircraft surfaces, microbial contamination control, and surface particle contamination minimization.
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