Cyanoacrylates adhesive properties

More recently, the copolymerization of ethyl cyanoacrylate with other 1,1 disubstituted electron deficient monomers and the effect of the monomers on adhesive properties have been studied. Monomers, such as diethyl methylene-malonate (DEMM), 8, were prepared [6,7]. Their homopolymers and copolymers... 

The adhesive properties the other monomers were also evaluated, alone and as mixtures with ethyl cyanoacrylate. The addition of DEMM to ECA has an obvious negative effect on adhesion, as can be seen in Fig. 5. 

To minimize the gradual embrittlement that can occur on aging of cyanoacrylate adhesives, plasticizers are added. Some of the materials, which have been used as plasticizers, include phthalates, phosphonates, acyl esters, succinates, and cyano-acetates. The use of allyl, methallyl, and crotyl phthalates is also claimed to improve thermal resistance properties in addition to plasticizing the adhesive [23]. 

The data also demonstrate that the addition of the thermoplastic, PMMA, does not have the significant effect on the toughness or adhesion properties as does the addition of the rubber, Vamac B-124. Clearly, the physical properties of the polymeric additive determine the magnitude of the adhesive physical property modifications, which result from their addition to an alkyl cyanoacrylate monomer. 

Ihe polymers of the 2-cyanoacrylic esters, more commonly known as the alkyl 2-cyanoacrylates, are hard glassy resins that exhibit excellent adhesion to a wide variety of materials. The polymers are spontaneously formed when their liquid precursors or monomers are placed between two closely fitting surfaces. Tile spontaneous polymerization of these very reactive liquids and the excellent adhesion properties of the cured resins combine to make these compounds a unique class of single-component, ambient-temperature-curing adhesive of great versatility (Table 3). The materials that can be bonded run the gamut from metals, plastics, most elastomers, fabrics, and woods to many ceramics. 

Reversion is usually much faster in flexible materials because water permeates them more easily. Hydrolysis has been seen in certain epoxy, polyurethane, and cyanoacrylate adhesives. The reversion rate also depends on the type and amount of catalyst used in the formulations and the degree of crosslinking. Best hydrolytic properties are obtained when the proper stoichiometric ratio of base material to catalyst is used. 

Poly(alkyl-cyanoacrylate) Nanoparticles The applications of poly(alkyl-cyanoacrylate) nanoparticles have been reviewed elsewhere and therefore only representative examples are described [102], Because of their adhesive properties, nanoparticles have the potential to prophylactically treat candidiasis of the oral cavity [121], Not surprisingly, poly(alkyl-cyanoacrylate) nanoparticles have been used to deliver drugs to tumors [122], Enhanced absorption and prolonged hypoglycemic effect were observed when insulin was delivered in poly(alkyl-cyanoacrylate) nanoparticles [121], Nuclear accumulation of antisense oligonucleotides into vascular smooth muscle cells was increased when delivered using poly(alkyl-cyanoacrylate) nanoparticles [123]. Dextran-coated poly(alkyl-... 

Early demonstration that the absorption of poly(methoxypropyl cyanoacrylate) can be accelerated in the presence of hquid absorbable oxalate polymers led Shalaby to develop a new family of methoxypropyl cyanoacrylate (MFC)/polyester formulations as tissue adhesives with a broad range of properties. These formulations were tailored to produce absorbable tissue adhesives with a range of adhesive properties and compositionally controlled compliance depending on the type and content of the absorbable polyester component in the formulation. 

As already stated, formulated cyanoacrylate adhesives contain low levels of additives that improve the performance profile of the product. They can be divided into two general groups those that modify the polymerization process and those that alter the properties of the final polymer. 

In summary, it can be stated that a large number of different surface treatments exist to improve the adhesional properties of PP. It should be stated here that some manufacturers of cyanoacrylate adhesives recommend special chemical primers which produce adhesion on PP without other treatment. In the experience of the author, this type of primer improves the adhesion but produces bonded joints that are insufficiently durable, especially under humid enAuronmental conditions. 

PACA are hard glassy polymers with a high polarity , and this explains their adhesive properties (Coover et al., 1959). The adhesive action of alkyl 2-cyanoacrylates was discovered during an investigation of a series of polymers derived from 1,1-disubstituted ethylenes. It was found that certain compounds of general structure ... 

As mentioned above, an important property of cyanoacrylates is their ability to form rapidly strong bonds as they undergo anionic/zwitterionic polymerization in the presence of hydroxyl or amino groups, such as with proteins or weak bases. For this reason, PACA have been extensively used in surgery because of their adhesive properties. 

The cyanoacrylate adhesives sold today are quite similar to the first product, Eastman 910. This is due to the fact that changes in the structure of the monomer have dramatic effects on the adhesive properties, and because there are very few modifying monomers which will successfully coreact with the cyanoacrylates under normal application conditions. Also, the monomers with the best adhesive properties were discovered early in the development of cyanoacrylates. Finally, research toward improving the deficiencies of these products had a slow start owing to the early manufacturing problems. Beginning in the late 1970s, however, a number of adhesives with improved performance were introduced. 

While the bulk of any cyanoacrylate formulation consists of monomer, a large number of modifiers have been used to impart desired properties to the composition. These include stabilizers, inhibitors, thickeners, plasticizers, dyes or colorants, adhesion promoters, and others. Each of these classes of modifier will be dealt with in subsequent parts of this chapter. Because of the variety of modifiers, and the variety of applications for cyanoacrylates, a bewildering number of cyanoacrylate adhesives are now commercially available. These can be generally divided into the following classifications adhesives of different viscosities and cure rates, adhesives based on different monomers, adhesives for the bonding of metal, plastic, rubber, or wood, various types of improved performance adhesives, i.e., heat, moisture, or impact resistant, and adhesives for bonding low surface... 

Polyalkyl cyanoacrylates are clear, colorless thermoplastics whose physical properties are roughly equivalent to those of other common thermoplastics such as PMMA or polystyrene. Because the majority of adhesives sold today are based on ethyl cyanoacrylate, the properties of polyethyl cyanoacrylate (PECA) will be discussed in detail, and existing data for other esters will be tabulated. 

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