The field to which the disclosure generally relates includes glues (adhesive materials) and shape memory polymeric (SMP) materials, and more specifically to a glue chemically grafted onto a shape memory polymeric surface whereby the amount of glue and solvent used in a bonding process may be minimized to achieve a quick drying bonding process.
Shape memory polymers (SMP's) represent responsive polymers that can fix to deformed temporary shapes and recover to their permanent (original) shapes only upon external stimuli. In particular, SMPs which are responsive to temperature and possessing one glass transition temperature (Tg) are finding increasing use in a wide array of products.
In an exemplary embodiment, a shape memory polymer material (SMP) including a glue material chemically grafted onto a surface of the SMP material is provided wherein the SMP material is capable of transforming between a permanent shape and a temporary shape.
In another exemplary embodiment, a method of gluing a substrate is presented including providing a shape memory polymer (SMP) material wherein the SMP material is capable of transforming between a permanent shape and a temporary shape; providing a dry glue chemically grafted to at least one surface of the SMP material; heating the SMP material above a glass transition temperature Tg of the SMP material; contacting the dry glue with a solvent to solvate said glue; contacting the solvated glue with at least a first substrate; and, drying the solvated glue to form an adhesion bond to said at least a first substrate.
In another exemplary embodiment, a product with an adhesive bond is provided, the adhesive bond including at least one layer of shape memory polymer (SMP) material wherein the SMP material is capable of transforming between a permanent shape and a temporary shape; a glue material chemically grafted to at least one surface of the SMP material; and, at least one substrate glued to the at least one glue containing surface of said SMP material.
Other exemplary embodiments of the invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while disclosing exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Exemplary embodiments of the invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the embodiment(s) is merely exemplary (illustrative) in nature and is in no way intended to limit the invention, its application, or uses.
In an exemplary embodiment, a glue material may be chemically grafted (chemically bonded) onto a shape memory polymer (SMP) surface to form a glue containing shape memory polymer surface. The term ‘chemically grafted’ is meant including at least one chemical bond formed between a chemical group comprising the SMP material and a chemical group comprising the glue material. It will be appreciated that the glue material is preferably different from the SMP material. A solvent may then be contacted onto the glue material above or below a Tg of the SMP material, and in one exemplary embodiment, above a Tg of the SMP material. A substrate may then be contacted onto the solvent activated glue on the SMP and the substrate and SMP cooled below the Tg of the SMP material to form the SMP material bonded to the substrate.
In an exemplary embodiment, the glue may be any glue that may be chemically grafted onto the SMP material and which may be solvated with a solvent. For example, the glue material includes solvent in a pre-adhesion forming state prior to drying to form an adhesion state. In some embodiments, exemplary glue materials may include ethylene-vinyl acetate, polyvinyl alcohol, polyurethanes, polyester, ethylene-vinyl acetate, polyvinyl acetate (PVA), polysulfides, and polyvinyl chloride (PVC). In select embodiments the solvents may include, but are not limited to, isopropanol, water, toluene or acetone.
In another exemplary embodiment, the shape memory polymer (SMP) material may include one or more glass transition temperatures (Tg) and/or Tm (melting points), hereinafter referred to generally as Tg.
For example, in one exemplary embodiment, referring to
In various embodiments, the at least one Tg of the SMP material may be within a range of from about 25° C. to about 200° C.
Referring
In various embodiments, the SMP material may include a rigid epoxy, an epoxy extender, and a crosslinking agent; or a rigid epoxy, a flexible crosslinking agent, and a flexible epoxy; or a rigid epoxy, a rigid crosslinking agent, and a flexible epoxy; or a rigid epoxy, a flexible epoxy, and a catalytic curing agent; or a rigid epoxy, a crosslinking agent, and a diluent; or a flexible epoxy, a crosslinking agent, and a diluent; or a rigid epoxy and a flexible crosslinking agent; or a flexible epoxy and a catalytic curing agent; or a flexible epoxy and a crosslinking agent; and wherein the rigid epoxy is an aromatic epoxy having at least two epoxide groups, the flexible epoxy is an aliphatic epoxy having at least two epoxide groups, the epoxy extender has one epoxide group, and the crosslinking agent is one of a multi-amine, an organic multi-carboxylic acid, or an anhydride, and the diluent is a monoamine or a mono-carboxylic acid. In various embodiments, the catalytic curing agent (or catalytic cure) promotes epoxy-to-epoxy or epoxy-to-hydroxyl reactions. The catalytic curing agent may include, but is not limited to, tertiary amines, amine salts, boron trifluoride complexes, or amine borates. In one embodiment, the components of the dry SMP material (which may also be a dry adhesive) may be present in an amount sufficient to provide, upon curing of the composition, an SMP material having a glass transition temperature (Tg) of from about 25° C. to about 200° C.
In another exemplary embodiment, the shape memory polymer (SMP) material may be formed from and/or include a rigid aromatic diepoxide (EPON 826), a flexible aliphatic diepoxide such as neopentyl glycol diglycidyl ether (NGDE), and an aliphatic diamine curing agent such as poly(propylene glycol)bis(2-aminopropyl)ether (Jeffamine D-230).
Still referring to
Referring to
In another exemplary embodiment, following heating of the SMP material above Tg, either prior to or following formation of a second shape e.g., 20B and 20B′, the glue material e.g., 26A, 26B may be contacted with a solvent material, e.g., by one or more of dipping, spraying, brushing, and the like. In one embodiment, it will be appreciated that the amount of solvent material contacted to the glue material e.g., 26A, 26B may be about equal to an amount sufficient to solvate the glue material, e.g., about the same volume or less of than the volume of the dry glue material. It will be appreciated that in some embodiments, the solvent may cause the glue material to be activated.
In another embodiment, the SMP material (e.g., layers 22 and 24) preferably remains substantially unsolvated (dry) while only the glue material e.g., 26A, 26B is solvated, although it will be appreciated that some of the solvent may contact exposed surfaces of the SMP material. It will further be appreciated that the preferred type of solvent is capable of solvating the dry glue material without detaching the grafted glue material from the surface of the SMP material.
In another exemplary embodiment, as shown in
In another embodiment, as shown in
In another embodiment, following contacting with applied stress the solvent containing glue material with one or more substrates e.g., 30A, 30B, to form the third shape e.g., 20C and 20C′ above a Tg of the SMP material, the SMP material, substrates, and solvent containing glue material may then be cooled to a temperature below Tg where an applied stress e.g., 32 may be released, prior to or following evaporation of the solvent, to form SMP material in respective shapes e.g., 20C and 20C′ and adhesion bonded through the glue material to the one or more substrates e.g., 30A, 30B.
For example, the second curved shape e.g., 20B,
Referring to
Among the various advantages of the embodiments include the reduction of the amount of solvent required in a gluing process which serves to reduce environmentally harmful vapors as well as to ensure a gluing process that has a quick drying time.
The above description of embodiments of the invention is merely exemplary in nature and, thus, variations thereof are not to be regarded as a departure from the spirit and scope of the invention.