Interfacial crosslinking

Solid microcapsules using maltodextrins or starch as matrices were incorporated into cosmetic, pharmaceutical, dietetic, and food compositions using the interfacial crosslinking of flavonoids. Such microcapsules prevented discoloration while maintaining both the anti-free radical and antioxidant activities of the flavonoids." ... 

Several other investigators have reported microencapsulation methods based upon polyelectrolyte complexes [289, 343]. For example, oppositely-charged polyelectrolytes (Amberlite IR120-P (cationic) and Amberlite IR-400 (anionic)) were recently used along with acacia and albumin to form complex coacervates for controlled release microcapsule formations [343]. Tsai and Levy [344,345] produced submicron microcapsules by interfacial crosslinking of aqueous polyethylene imine) and an organic solution of poly(2,6 dimethyl... 

Research. It is formed by interfacially crosslinking a monomeric amine on a microporous polysulfone support membrane. 

A promising application of the self-assembly of nanoparticles at droplet surfaces is the interfacial crosslinking of chemically functionalized nanoparticles. This enables the encapsulation of water-soluble or oil-soluble materials inside the resulting nanocontainers. By varying the concentration of reactive moieties, it will be possible to control the permeability and strength of these nanostructured membranes. 

Table 5.5 lists the best performance data obtained for some piperazine oligomer membranes interfacially reacted with isophthaloyl chloride. The objective of these tests was to achieve single-pass seawater desalination membranes. As such, the presence of free carboxylate groups was avoided. Use was made of the tri-mesoyl chloride or alternate triacyl halides in the oligomer formation step, and diacyl chlorides in the interfacial reaction step. A few examples of seawater desalination membranes were obtained. Best results were seen for piperazine-cyanurate prepolymers interfacially crosslinked by isophthaloyl chloride, but fluxes were low in view of the operating test pressure of 1,500 psi. 

The radiative-oxidative stability of low density PE, LDPE, with PP blends were found to be more stable than pure PP [Gorelik et al., 1992]. This was explained as due to a decrease in crystallite size and possible interfacial crosslinking. The thermal stability after irradiation was considerably impaired in comparison with untreated material [Minkova et al., 1992]. This was due to the presence of free radicals within the PP component (which itself is significantly more susceptible to thermal degradation after irradiation than LDPE). 

These results confirm that the number of interfacial crosslinks depends on the interdiffusion depth and that a critical depth has to be reached to obtain efficient crosslinks for high interfacial strength. 

There are a wide range of functional monomers which can be copolymerized with the principal monomers described in the previous section. These functional monomers are often used in very small amounts (typically 1-3% in a formulation) and provide reactive sites for crosslinking, surface modification, and post-polymerization processing of latex particles [21]. Examples of the roles that these functional monomers play during the interfacial crosslinking process are also given in this section. There are several major classes of these functional monomers, based on the type of reactive moiety which is introduced into the latex particle. These moieties include ... 

Recently, a series of styrene-n-butyl acrylate copolymer latexes were prepared by conventional or miniemulsion polymerization techniques which incorporated TMI and/or methacrylic acid (MAA), and the interfacial crosslinking behaviour of films derived firom these latexes was investigated [33]. It was shown that crosslinking was dramatically enhanced in the presence of MAA. However, films prepared with TMI also crosslinked in the presence of atmospheric moisture with time at room temperature. This work also demonstrated the stability of... 

The thermodynamics of mixing predict that, as a general rule, the polymers will form a two-phase system, and experimental (microscopic) observations support this prediction. The problem in blend curing is to obtain a degree of interfacial crosslinking between dissimilar phases. 

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