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-10626098-B2
Publication Date
2020-04-21
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
This invention provides copoly(imide oxetane) materials that combine the mechanical, thermal, chemical, and optical properties of polyimides with low surface energy characteristics. The copoly(imide oxetane)s are prepared using a minor amount of an amino-terminated fluorinated oxetane-derived oligomer. Sufficient fluorine-containing segments migrate to the exterior surface of the polymeric material, affording low surface energies and producing coatings and articles characterized by an anisotropic fluorine composition. This allows the coatings and articles to have the desired surface properties while maintaining the inherent bulk properties of polyimides.
The problem solved by this invention arises from the difficulty of modifying high-performance polymeric materials like polyimides to impart low adhesion or low surface energy properties without degrading their essential properties such as mechanical strength, thermal stability, chemical resistance, and optical clarity. Traditional methods require significant amounts of fluorinated modifiers that disperse throughout the bulk, wasting expensive additives and potentially impairing bulk properties. This invention overcomes those limitations by achieving low surface energy with very low fluorinated oxetane content, as little as below about 0.5 mass percent, enabling retention of polyimide performance while enhancing surface hydrophobicity and adhesion resistance.
The invention also details the chemical structures and synthesis methods for the fluorine-containing oxetane-derived oligomers and their incorporation into polyimide matrices. It provides processes for making copoly(amic acid oxetane)s and for imidization to form the final copoly(imide oxetane)s. Moreover, the invention describes coatings and articles of manufacture embodying the copolymers, exhibiting anisotropic fluorine distribution with surface enrichment, thereby achieving superior surface low energy characteristics.
Claims Coverage
The patent contains several independent claims that cover the fluorinated oxetane oligomers, their incorporation into copoly(imide oxetane)s, and the resulting polymer composites.
Fluorinated oxetane-derived oligomer structure
An oligomer represented by the formula (E)yR1—C(O)—O-Qp-(R6—O)q-Qr-C(O)—R1(E)y where the variables define specific fluorinated oxetane substituents, with E being —NO2 or —NH2, R1, R6, and Q representing defined hydrocarbon or substituted hydrocarbon linkages, forming the fluorine-functionalized segments.
Copoly(imide oxetane) composition with low fluorinated oligomer content
Copolymers containing 0.001 to 15 mass percent of the amino-terminated fluorinated oxetane oligomer integrated into a polyimide backbone, enabling low surface energy properties through surface fluorine enrichment.
Polymer composite containing fluorinated oxetane oligomer and particulate filler
A polymer composite comprising copolymers with the fluorinated oxetane oligomer and particulate fillers sized below about 0.5 micron, resulting in a water contact angle of at least 100°, enhancing surface low energy properties.
The independent claims focus on the chemical structures of fluorinated oxetane oligomers, their incorporation in low amounts into copoly(imide oxetane)s, and the formation of composites including particulate fillers to achieve low surface energy surfaces with maintained polyimide properties.
Stated Advantages
Copoly(imide oxetane)s achieve low surface energy with very minor fluorinated oxetane oligomer content, preserving the mechanical, thermal, chemical, and optical properties of polyimides.
The invention enables surface modification without compromising bulk polymer properties, allowing tailoring of surface hydrophobicity efficiently.
Improved surface clearance and reduced dust adhesion compared to homopolyimide coatings, as demonstrated by performance evaluations.
Anisotropic distribution of fluorine at the surface leads to enhanced surface low energy behavior with minimal additive material usage.
Documented Applications
Coatings and articles of manufacture exhibiting low surface energy and hydrophobicity while retaining polyimide performance characteristics.
Use in environments requiring passive mitigation of surface fouling, contamination, or adhesion such as marine biofouling reduction, membrane fouling, insect adhesion on aircraft, microbial contamination control, and dust mitigation.
Coatings on various substrates including metal, ceramic, glass, wood, paper, fibers, textiles, membranes, or polymer surfaces.
Polymeric matrix articles formed by casting, molding, or extruding incorporating the fluorinated oxetane oligomers for low adhesion surfaces.
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