Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Monomer film forming

PVPA A BASF/ISP/PVP- Various monomer Film forming adhesives... [Pg.5312]

As with polyesters, the amidation reaction of acid chlorides may be carried out in solution because of the enhanced reactivity of acid chlorides compared with carboxylic acids. A technique known as interfacial polymerization has been employed for the formation of polyamides and other step-growth polymers, including polyesters, polyurethanes, and polycarbonates. In this method the polymerization is carried out at the interface between two immiscible solutions, one of which contains one of the dissolved reactants, while the second monomer is dissolved in the other. Figure 5.7 shows a polyamide film forming at the interface between an aqueous solution of a diamine layered on a solution of a diacid chloride in an organic solvent. In this form interfacial polymerization is part of the standard repertoire of chemical demonstrations. It is sometimes called the nylon rope trick because of the filament of nylon produced by withdrawing the collapsed film. [Pg.307]

PVP/VA BASF/ISP/PVP-VA copolymers various monomer ratiosin film forming adhesives for hairsprays. [Pg.534]

Poly(vinyl fluoride) was first introduced in the early 1960s, in film form, by Du Pont under the trade name Tedlar. Details of the commercial method of preparing the monomer have not been disclosed but it may be prepared by addition of hydrogen fluoride to acetylene at about 40°C. [Pg.376]

It may also be possible to crosslink the acrylic PSA with the help of multifunctional acrylates or methacrylates [87], These monomers can simply be copolymerized with the balance of the other monomers to form a covalently crosslinked network in one step. Since the resulting polymer is no longer soluble, this typ)e of crosslinking is typically limited to bulk reactions carried out as an adhesive coating directly on the article or in emulsion polymerizations where the crosslinked particles can be dried to a PSA film. [Pg.498]

S.3.2 Sol-Gel Encapsulation of Reactive Species Another new and attractive route for tailoring electrode surfaces involves the low-temperature encapsulation of recognition species within sol-gel films (41,42). Such ceramic films are prepared by the hydrolysis of an alkoxide precursor such as, Si(OCH3)4 under acidic or basic condensation, followed by polycondensation of the hydroxylated monomer to form a three-dimensional interconnected porous network. The resulting porous glass-like material can physically retain the desired modifier but permits its interaction with the analyte that diffuses into the matrix. Besides their ability to entrap the modifier, sol-gel processes offer tunability of the physical characteristics... [Pg.120]

The electrochemical reduction reactions of the central metallotetraphenylporphyrin moieties are, fortunately, much more straightforwardly analyzed (1,2). With few exceptions, when transferred to a fresh supporting electrolyte solution, films formed from ECP reactions like Fig. 2A exhibit electrochemical reduction waves at or very near the potentials observed for reductions of the corresponding monomers dissolved in solutions. For example, a film formed oxidatively as in Fig. 2A gives in fresh electrolyte the reductive gyclic voltammogram of Fig. 2B. [Pg.412]

The film that was obtained was very thin and it was not possible to grow thicker films. This result was most probably caused by absorption of the incident radiation by the film formed on the interior of the quartz reactor, thereby blocking the incoming UV light and preventing the activation of the monomer and continous polymerization. The UV absorption of the monomer and of polymer film reside in the same region. Figure 18.5 and 18.6 show the UV absorption spectra of the precursor and the polymer film as deposited on the quartz surface, respectively. [Pg.289]

An additional important feature of this class of polymers lies in the fact that their polymerisation and doping processes may be driven by a single electrochemical operation which, starting from the monomer, first forms the polymeric chain and then induces its oxidation and deposition in the doped form as a conductive film on a suitable substrate. The polymerisation reaction may be basically described as an electrophilic substitution which retains the aromatic structure and proceeds via a radical cation intermediate ... [Pg.235]

The use of nitroxyls that are amenable to immobilisation in a polymer layer around the anode would be an ideal way of constraining the catalyst where it can be regenerated electrochemically. Attempts to utilise a poly(pyrrole) film formed by anodic oxidation of the monomer 5 led to a system that will oxidise alkanols but which is unstable in continuous use [40], A more satisfactory polymer layer is... [Pg.268]

Monomer (reactive thinner) 0-6 Viscosity adjustment, contributes to film forming... [Pg.144]

The fullerene monomer (200), made by the cycloaddition of quadricyclane (199) to Cgo (equation 56), can be copolymerized with an excess of norbomene in the presence of 8 (R = Me) to yield a high-molecular-weight, soluble, film-forming copolymer (86% cis), containing 1% of C60 derivative and exhibiting electronic and electrochemical properties which are typical of the carbon cluster536. [Pg.1571]

Thus the use amphiphilic macromonomers is another method to achieve the particle formation and their subsequent stabilization. Macromonomers can be pre-reacted to form graft copolymers, which are be introduced into the reaction medium afterwards. Macromonomers can also be copolymerized with classical monomers in situ to form graft copolymers. This is a simple and flexible method for producing monodisperse micron-sized polymer particles. Macromonomers can produce ion-free acrylic lattices with superior stability and film forming properties compared to conventional charge stabilized lattices. These non-con-... [Pg.10]

Parylene-C, the trade name of the film formed from the Union Carbide Corp. brand of dichloro-p-xylylene, is a vapor deposited film formed by the reaction shown in Figure 1. The solid dimer(I) is vaporized and pyrolyzed at 650° C to 750 C to the reactive olefinic monomer, chloro-p-xylylene(II), which polymerizes on cool surfaces in the low pressure deposition chamber to form the crystalline linear polymer poly(chloro-p-xylylene) (III) (5). [Pg.109]

Similarly, vinylferrocene copolymerized with a small amount of a film forming monomer displays photoconductivity108 when complexed with 2,4-dinitrophen-anthrolinequinone. [Pg.32]

Recently Uniqema has introduced commercially a Surfmer under the trade name of Maxemul 5011. Maxemul is produced by esterification of an unsaturated fatty anhydride with a methoxy PEG such that the reactive group is close to the hydrophilic moiety [ 34 ]. Stable latexes with a solid content of 52% were produced in the seeded emulsion polymerization of film-forming methyl methacrylate/butyl acrylate/acrylic acid (3% Surfmer on monomers, constant monomer feeding rate over 4 h, potassium persulfate/sodium metabisulfate redox initiator). The latexes were stable to electrolytes but not to freeze-thaw. [Pg.221]

Figure 9 The emission spectrum of a tetracene film evaporated onto a glass substrate kept at 89 K and the emission monitored at 180 K (full circles). Its decomposition into Gauss profiles (II, III, IV, V) is shown by solid lines. The dashed curve is the sum of the gaussians. The lacking band I (=540 nm) is characteristic of the monomer emission from crystalline films formed at T > 140 K. Adapted from Ref. 72. Figure 9 The emission spectrum of a tetracene film evaporated onto a glass substrate kept at 89 K and the emission monitored at 180 K (full circles). Its decomposition into Gauss profiles (II, III, IV, V) is shown by solid lines. The dashed curve is the sum of the gaussians. The lacking band I (=540 nm) is characteristic of the monomer emission from crystalline films formed at T > 140 K. Adapted from Ref. 72.
Monomer film or wall at a specified temperature and relative humidity. A relatively simple compound which can react to form a polymer. [Pg.150]

Tough film forming monomer with good adhesion properties. [Pg.186]

Poly(carbodiimides) are sometimes used as adhesive primers. Film forming carbodiimide homo- or copolymers have been used in microencapsulation techniques for pressure sensitive copy paper. Oligomeric acylureas are obtained from polyunsaturated carboxylic acids and carbodiimides as monomers for coatings. ... [Pg.270]

Positional isomerism is not generally an important issue in syntheses of polymers with backbones which do not consist exclusively of enchained carbons. This is because the monomers which form macromolecules such as poly(ethylcne terephthalate) (1-5) or nylon-6,6 (1-6) are chosen so as to produce symmetrical polymeric structures which facilitate the crystallization needed for many applications of these particular polymers. Positional isomerism can be introduced into such macromoicculcs by using unsymmetrical monomers like 1,2-propylene glycol (4-8), for example. This is what is done in the synthesis of some film-forming polymers like alkyds (Section 5.4.2) in which crystallization is undesirable. [Pg.123]


See other pages where Monomer film forming is mentioned: [Pg.41]    [Pg.41]    [Pg.270]    [Pg.540]    [Pg.210]    [Pg.526]    [Pg.6]    [Pg.97]    [Pg.144]    [Pg.41]    [Pg.173]    [Pg.154]    [Pg.168]    [Pg.677]    [Pg.9]    [Pg.609]    [Pg.526]    [Pg.170]    [Pg.262]    [Pg.210]    [Pg.113]    [Pg.10]    [Pg.6]    [Pg.364]    [Pg.173]    [Pg.4]    [Pg.73]    [Pg.710]   
See also in sourсe #XX -- [ Pg.170 ]




SEARCH



Film forming

© 2024 chempedia.info