United States of America As Represented by the Administrator of Nasa

The United States of America As Represented by the Administrator of the

Christopher J Wohl, Jr

John W Connell

Joseph G Smith, Jr

Emilie J Siochi

Frank L Palmieri

Marcus Anthony Belcher

Paul M Danehy

Yi Lin

John W Hopkins

Jason E Danley

Jereme R Doss

Pacita I Tiemsin

John M Gardner

Ronald K Penner

Vincent B Cruz

Frank M Palmieri

Lilly Lynn Balderson

Devon Beck

Allison M Crow

William T Kim

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.

Anisotropic copoly(imide oxetane) coatings and articles of manufacture, copoly(imide oxetane)s containing pendant fluorocarbon moieties, oligomers and processes therefor

In an illustrative example, one or more coating formulations may be used and may have characteristics useful in different situations. During evaluations, a plurality of coating formulations comprising epoxy resins and diamine hardeners were prepared and evaluated with regards to impact ice adhesion strength and durability. Alone, such coating formulations provided a significantly reduced impact ice adhesion strength as compared to uncoated aluminum and/or stainless steel surfaces. However, a durability of the coatings, when applied to aluminum or stainless steel surfaces, was insufficient to be considered for use on external aircraft surfaces. By including nano-sized and/or micro-sized particles as additives to the coating formulations, resulted in improved durability without significantly reducing ice adhesion performance of the resin base.

Durable contamination resistant coatings

Embodiments provide ice adhesion mitigating surface coatings and methods for generating the same. Embodiments may provide anti-icing coating with at least one monomeric species exhibiting molecular flexibility. The molecular flexibility in the monomeric species may be imparted through an aliphatic or heteroaliphatic chain that may exist as a portion of the monomer backbone, as a pendant group, or as both the portion of the monomer backbone and the pendant group. In various embodiments epoxy coatings including an epoxy resin and an amine-terminated hardener may be generated. At least a portion of the amine-terminated hardener may include at least a monomeric species that exhibits molecular flexibility arising from an aliphatic chain or heteroaliphatic chain that may be within the polymer backbone and/or may persist as a pendant group.

Coatings with molecular flexibility for ice adhesion mitigation

A soft lithography template or stamp is made by casting a polydimethysiloxane (PDMS) or other suitable elastomeric precursor onto a master pattern. The master pattern may be formed utilizing known micro-fabrication techniques. The PDMS template includes an inverse copy of the micro-structures on the master pattern, and can be placed into a mold used to prepare a carbon-fiber reinforced polymer composite part or other polymer molding systems where a matrix material passes through a fluid state during the cure process. The liquid resin material flows into the structures on the surface of the PDMS template and hardens during the curing cycle. After the part is released from the mold, the PDMS template can be peeled from the surface of the part to reveal the free standing micro structures which are a replica of the master pattern.

High pressure soft lithography for micro-topographical patterning of molded polymers and composites

Various embodiments provide ice mitigating surface coatings and methods for applying ice mitigating surface coatings. Various embodiment ice mitigating surface coatings may be formed by hydrolysis of one or more substituted n-alkyldimethylalkoxysilanes terminated with functionalities having the following characteristics with respect to water: 1) non-polar interactions; 2) hydrogen bonding through donor and acceptor interactions; or 3) hydrogen bonding through acceptor interactions only. The substituted n-alkyldimethylalkoxysilanes of the various embodiments may include methyl terminated species, hydroxyl terminated species, ethylene glycol terminated species, and methoxyethylene glycol terminated species. Various embodiment ice mitigating surface coatings may be applied to metal surfaces, such as aluminum surfaces. Various embodiment substituted n-alkyldimethylalkoxysilanes may have an aliphatic chain that is saturated and liner or branched or that is partially unsaturated and liner or branched.

Hydrogen-bonding surfaces for ice mitigation

Various embodiments provide random copolyimides that may possess the mechanical, thermal, chemical and optical properties associated with polyimides yet achieve a low energy surface. In various embodiments, the copolyimides may be prepared using a minor amounts of a diamino terminated fluorinated alkyl ether oligomer and a diamino terminated siloxane oligomer. The various embodiments include processes for making the copolyimides containing fluorine and silicon surface modifying agents and anisotropic coatings and articles of manufacture from them. Thus the coatings and articles of manufacture made with the copolyimides of the various embodiments may be characterized as having an anisotropic fluorine and silicon composition and low surface energy.

Synthesis of copolyimides containing fluorine and silicon surface modifying agents

Various embodiments provide epoxy modified fluorinated urethane compositions that may provide desirable bulk mechanical properties of conventional coatings, adhesives, or structural matrix resins, while simultaneously exhibiting surface properties that may reduce surface contamination. Various embodiments provide formulations comprising epoxy modified fluorinated alkyl ether including urethane oligomer or polymer resins that may possess the requisite thermal, mechanical, chemical, and optical properties while achieving a low surface energy. In various embodiments, such resins may be prepared from random urethane oligomer compositions including fluorinated alkyl ether segments, in which the oligomers may be terminated with amino groups and subsequently reacted with epoxy including monomers or oligomers.

Synthesis and development of polyurethane coatings containing flourine groups for abhesive applications

Various embodiments provide dye-doped polystyrene microspheres generated using dispersion polymerization. Polystyrene microspheres may be doped with fluorescent dyes, such as xanthene derivatives including Kiton Red 620 (KR620), using dispersion polymerization. Certain functionalities, such as sodium styrene sulfonate, may be used to shift the equilibrium distribution of dye molecules to favor incorporation of the dye into the particles. Polyelectrolyte materials, such as poly(diallyldimethyl ammnonium chloride), PolyDADMAC, may be used to electrostatically trap and bind dye molecules within the particles. A buffer may be used to stabilize the pH change of the solution during dye-doped polystyrene microsphere generation and the buffer may be selected depending on the pKa of the dye being incorporated. The various embodiments may provide dye-doped polystyrene microspheres, such as KR620-doped polystyrene microspheres that are non-toxic and non-carcinogenic. These non-toxic and non-carcinogenic dye-doped polystyrene microspheres may be suitable for use in wind tunnel testing.

Dye doped polymer microparticles

Anisotropic copoly(imide oxetane) coatings and articles of manufacture, copoly (imide oxetane)s containing pendant fluorocarbon moieties, oligomers and processes therefor

A method for bonding composite substrates includes coupling a first co-cure prepreg layer having a first off-set amine to epoxide molar ratio onto a surface of a first composite substrate and coupling a second co-cure prepreg layer having a second off-set amine to epoxide molar ratio onto a surface of a second composite substrate. The first and second composite substrates are cured to the first and second co-cure prepreg layers, respectively, using a first cure cycle (including B-stage and cure temperatures) to form a first and a second co-cure prepreg layer portion. The method further includes coupling the first co-cure prepreg layer portion to the second co-cure prepreg layer portion and applying a second cure cycle to cure the first co-cure prepreg layer portion of the first composite substrate to the second co-cure prepreg layer portion of the second composite substrate to form a monolithic covalently bonded composite structure.

Off-set resin formulations and blocking/deblocking resin systems for use as a 'co-cure-ply' in the fabrication of large-scale composite structure

A method of forming a smooth aerodynamic surface that permits laminar flow of air over the smooth aerodynamic surface. Selected portions of a surface of a substrate material are ablated utilizing a laser to form a treated substrate surface having a predefined roughness. The treated substrate surface is coated to form a solid layer of material having a smooth aerodynamic surface that promotes laminar flow. The solid layer of material has a lower modulus of elasticity than the substrate material to provide durotaxis when an insect impacts the solid layer of epoxy material to thereby reduce adhesion of insect residue or other matter to the smooth aerodynamic surface.

Influence on surface interactions by substructure topography

A method for bonding composite structures which includes providing a first and second composite substrate and coupling a co-cure prepreg tape having chemically protected polymerizable functional groups onto a surface of both the first and second composite substrates. The first and second composite substrates are then cured to the co-cure prepreg tape at a first temperature to form a co-cure prepreg tape portion where the first and second composite substrates are fully cured and the co-cure prepreg tape is partially cured. The co-cure prepreg tape portion of the first composite substrate is then coupled to the co-cure prepreg tape portion of the second composite substrate and a deprotection initiator is applied to facilitate deprotection of the chemically protected polymerizable functional groups and cure the co-cure prepreg tape portion of the first and second composite substrates to form a single covalently bonded composite structure.

Blocking/deblocking resin systems for use as a 'co-cure-ply' in the fabrication of large-scale composite structure

Surface energy of a substrate is changed without the need for any template, mask, or additional coating medium applied to the substrate. At least one beam of energy directly ablates a substrate surface to form a predefined topographical pattern at the surface. Each beam of energy has a width of approximately 25 micrometers and an energy of approximately 1-500 microJoules. Features in the topographical pattern have a width of approximately 1-500 micrometers and a height of approximately 1.4-100 micrometers.

Growing community of inventors

Portsmouth, VA, United States of America

Christopher J Wohl, Jr