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Vinyl functionalized cross-linkers

Numerous other cross-linkers may be used. For the trifunctional cross-linkers, the R group may be methyl, ethyl, vinyl, and several other groups, with methyl the most common. In some cases tetrafunctional and higher-functionality cross-linkers or polymeric cross-linkers may also be employed. The acetic add cure system should be avoided where substrates are subject to acid corrosion. [Pg.803]

Molecular imprinted polymers MIPs exhibit predetermined enan-tioselectivity for a specific chiral molecnle, which is nsed as the chiral template dnring the imprinting process. Most MIPs are obtained by copolymerization from a mixture consisting of a fnnctional mono-nnsatn-rated (vinylic, acrylic, methacrylic) monomer, a di- or tri-nnsatnrated cross-linker (vinylic, acrylic, methacrylic), a chiral template (print molecnle) and a porogenic solvent to create a three-dimensional network. When removing the print molecnle, chiral cavities are released within the polymer network. The MIP will memorize the steric and functional binding featnres of the template molecnle. Therefore, inclusion of the enantiomers into the asymmetric cavities of this network can be assumed as... [Pg.477]

Macromers can also be used as cross-linkers between already formed polymers when both ends are active. These functional groups could be either two vinyl ends or two Lewis acids or bases such as two hydroxyl or amine groups. Interpenetrating polymer networks (IPNs) and related structures such as dendrites and stars can also be formed using macromers. [Pg.504]

The state-of-the-art silicone systems used in label stock application are normally solventless and thermal curing. Base polymers for these systems are vinyl-functionalized polydimethylsiloxanes having viscosities of around 200 - 600 mPa.s. Cross-linkers normally are hydride-functionalized polydimethylsiloxanes with a viscosity of around 25 mPa.s. These two components are cross-linked by a platinum catalyst, which can be the Karstedt catalyst. Additionally an inhibitor is added to the silicone mixture to prevent curing before it is applied on the substrate. These inhibitors ate... [Pg.704]

Most functional monomers and cross-linkers contain one or more vinyl functionalities. Polymerization of this type of compound for the preparation of MIPs is traditionally performed as a free-radical polymerization, initiated via either ther-molytic or photolytic homolysis of an initiator. One of the most commonly used free radical initiators for this purpose is 2,2 -azobis (isobutyronitrile) (AIBN). Other examples of free-radical polymerization initiators are phenyl-azo-triphenyl-methane, tert-butyl peroxide (TBP), acetyl peroxide, benzoyl peroxide (BPO), lauroyl peroxide, tert-butyl hydroperoxide and tert-butyl perbenzoate. [Pg.30]

Zhu and coworkers have reported the synthesis of functionalized poly(vinyl alcohol) resins for use as scavengers [13]. This was achieved via inverse suspension polymerization along side epichlorohydrin as a cross-linker. These resins were found to have excellent swelling characteristics in DMF, CH3OH, dioxane, THF, CH2C12 and H20. These were then functionalized with glutaric aldehyde to provide a polymer-supported aldehyde (Scheme 8.8). [Pg.189]

Ester hydrolysis is most conveniently used because (1) its reaction mechanism is well established, and (2) both substrate and transition state analogs are easy to obtain. In Fig. 8.8b, phosphonic acid (2) is used as a transition state analog of the hydrolysis of substrate 3 [26]. A vinyl monomer of amidine 1 is chosen as a functional monomer because it readily forms stable complexes with the carboxylic acid ester and the phosphonic acid monoester. The imprinted polymers are synthesized in THF from 1 (the monomer), 2 (the template), and ethylene glycol dimethacrylate (the cross-linker) by using AIBN as the radical initiator. [Pg.137]

One of the more common two-part cure chemistries is based on the addition reaction of Si—H cross-links with vinyl functional polymers using platinum catalysts. This chemistry is shown below. One advantage of this addition chemistry is that it produces no cure by-products. Another common two-part chemistry involves condensation cure with alkoxysilane cross-linkers using Sn(IV) catalysts. [Pg.803]

A fluorescent sensor for dansyl-phenylalanine (dansyl-Phe-OFl) (Fig. 2, 1) has been successfully constructed by using methacrylic acid (MAA) and 2-vinyl-pyridine (2VPy) as the functional monomers and ethylene glycol dimethacrylate (EDMA) as the cross-linker. The fluorescence of the imprinted polymers upon analyte binding was detected using fiber optics, and the signal was found to be a function of the analyte concentration. The sensor also showed a moderate degree... [Pg.702]

Different types of water-based emulsions are used in EPI adhesives. The most common are poly(vinyl acetate) (PVAc) emulsion, ethylene vinyl acetate (EVAc) emulsion, vinyl acetate-acrylate copolymerized (VAAC) emulsion, acrylic-styrene (AcSt) emulsion or styrene-butadiene rubber (SBR) latex or modified versions of these emulsion types [1, 8, 9], It has also been reported that tri- or ter-polymer emulsions like vinyl acetate-butyl acrylate-hydroxypropyl methacrylate or emulsions with different combinations of block copolymers can be used [4], Emulsion polymers containing cross-linking functional groups are especially well suited [4,6, 9]. The choice of emulsion(s) will, to a large extent, influence the adhesive properties such as setting time, bond quality, heat resistance, and moisture resistance. EPI adhesive systems are, however, very complex and the total composition (including the choice of cross-linker) and the interaction between the different components will determine the properties of the adhesive. Due to this it is difficult to describe in detail the effect of choosing one type of emulsion over the other. [Pg.249]

A large variety of hyperbranched polymers with acrylate, vinyl ether, allyl ether, or epoxy functions were studied as multifunctional cross-linkers in coatings and in thermosets, using thermal as well as UV curing methods Clearly, polyesters are most prominent in the field, with the Perstorp Boltom products leading in technical studies. The commercialized poly(esteramide)s from DSM, sold under the trade name Hybrane polyethylenimines from BASF AG, available under the trade name TupasoF and poly(urethane)s (PUs) and polyesters developed by BASF are examples for hyperbranched polymers suited for coatings and resin products. [Pg.179]

Thus the versatility of lEM suggests a whole range of applications in poly isocyanates, poly vinyl-functionalized resins and polymerizable derivatives. In all of these applications lEM allows latent cross-linking or grafting because of its two independent, low-temperature cure functionalities. The majority of applications reported to date utilize lEM as a latent cross-linker or graft site to make resins suitable for use in coatings or adhesives. [Pg.779]

The most commonly used suspending agents are cellulose derivatives, poly-aciylate salts, starch, poly(vinyl alcohol), gelatin, talc, and clay derivatives (95). The important function these agents must serve is to prevent the coalescence of monomer droplets during the course of the polymerization (114). Thickeners can also be added to improve suspension quality (95). Other additives such as lauryl alcohol, stearyl acid or cetyl alcohol lubricants and di- or trivinyl benzene, dial-lyl esters of dibasic acids, and glycol dimethacrylates cross-linkers are used to improve bead imiformity and bead performance properties. [Pg.162]

MIPs are highly linked polymers, which can be synthesized by a typical three-step imprinting process, depicted in Figure 11. First, an imprint molecule or template forms a complex with functional monomers. The template is usually a molecule with the same or similar structure as analyte. Then, the complex is copolymerized with cross-linkers to form a polymer matrix typically via free radical polymerization. The functional monomer and crosslinker usually have vinyl or acrylic groups, which are commercially available. Finally, the template is removed from the matrix to create binding sites for analytes. [Pg.3349]

A different MWNTs-MIPs composites was prepared by using dopamine as a template molecule by the selective copolymerization of methacrylic acid and trimethylolpropane trimethacrylate in the presence of the template and vinyl group functionalized MWNT surface (Kan et al., 2008b). In this work, for grafting MIPs on MWNTs, the vinyl group was first introduced on the surface of MWNTs, which directed the selective polymerization of functional monomers and cross linkers in the presence of DA on the MWNTs surface. The thickness of the MIPs can be adjusted by changing the concentration... [Pg.196]

By a surface imprinting technique, in Zhang H. et al., 2011, a comfX)site imprinted material, on the basis of a MWCNTs-incorporated layer using melamine as a template, methacrylic acid as a functional monomer, and ethylene glycol dimethaciylate as a cross-linker, was synthesized. In this work, the poly(acrylic-acid)-functionalized CNTs were synthesized to increase the diameter of CNTs. Then, the vinyl group was introduced to the surface of poly(acrylic-acid)-functionalized CNTs by an amidation Using Melamine as a template molecule, imprinted CNT composite material was fabricated by a thermal fX)lymeiization. Applied as a sorbent, the imprinted materials were used for the determination of Melamine in the spiked sample by online SPE combined with HPLC. [Pg.198]


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See also in sourсe #XX -- [ Pg.30 ]




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Cross function

Cross-linker

Vinyl functions

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