Dichloro-p-xylylene

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). 

Polypropylene/polyethylene copolymer 23.6 6 dichloro-p-xylylene) 25 tm film 275 6... 

By attaching one chlorine atom to the xylylene ring (Parylene C), the permeability to moisture and other gases, can be significantly reduced. Polymers of dichloro-p-xylylene have better electrical and thermal properties as ordinary PPXs. The introduction of fluorine atoms still improves the thermal resistance. 

Dichloro[2.2]paracyclophane, 93 Dichloro-p-xylylene, 76 Dicumyl peroxide, 155... 

Various types of parylenes are sold. There are four forms of parylene. Parylene-N is the polymer of p-xylylene. Parylene-C or Galaxyl parylene-C is polyCclfloro-p-xylylene). Parylene-D is poly(dichloro-p-xylylene). Parylene-HT is poly[(2,3,5,6-tetrafluoro-1,4-phenylene) (1,1,2,2-tetrafluoro-1,2-ethanediyl)]. Suppliers and commercial grades are shown in Table 2.7. Tradenames appearing in the references are shown in Table 2.8. 

The widely used Parylene C owes its popularity principally to the room-temperature volatility of its monomer. The Parylene C monomer, chloro-p-xylylene, has become the de facto performance standard. By comparison, the Parylene N monomer, p-xylylene itself, is too volatile and would perform better in a sub-ambient-temperature deposition system. The Parylene D monomer, dichloro-p-xylylene [85586-88-5] is too heavy, and causes distribution problems in larger deposition systems. 

Preparation of Copolymer of Chloro- and Butyl- -xylylene. Mixtures of dichloro-di-p-xylylene and butyl-di-p-xylylene were prepared and melted to ensure homogeneity. The mixture was placed in the distillation zone, and the reaction was carried out in the usual fashion. The copolymers formed in the initial polymerization zone which was maintained at 90°-100°C. Poly-p-xylylene formed in the final, air-cooled zone. At... 

Dichloro-di-p-xylylene (gram) Butyl-di-p-xylylene (gram)... 

Copolymerization of Chloro- and Dichloro-/>-xylylene. Trichloro-di-p-xylylene (XVIII) was obtained by chlorination of di-p-xylylene with three molar equivalents of chlorine. Pyrolysis yielded monomers XV and XIX, which were condensed and polymerized on a 90 °C. surface. A quantitative yield of product was obtained. The product was transparent, tough, self-extinguishing, had a softening point above 280°C., and exhibited the correct elemental analysis for copolymer XX. Owing to the low solubility of the chlorinated poly-p-xylylenes, no attempts... 

Copolymers of ethyl- and chloro-p-xylylene were also prepared by pyrolytic polymerization of mixtures of dichloro-di-p-xylylene and diethyl-di-p-xylylene at 50°C. This is an example of preparation of a copolymer by pyrolysis of a mixture of two disubstituted di-p-xylylenes. 

Example 1 Encapsulation of Lithium Aluminum Hydride with Poly(chloro-p-xylylene). In the distillation zone were placed 5.0 grams of dichloro-di-p-xylylene. In a 4-oz. polyethylene bottle were placed 10.0 grams (400 pellets) of lithium aluminum hydride (LAH). LAH was obtained from Metal Hydrides, Inc., as 1/8-inch diameter pellets. The bottle was positioned in the coating chamber, the system was... 

Example 2 Encapsulation of 3/16-inch Sodium Hydroxide Pellets with Poly( chloro-p-xylylene ). Fifty grams of sodium hydroxide pellets were encapsulated with polymerizing chloro-p-xylylene generated by pyrolysis of 5.0 grams of dichloro-di-p-xylylene over a 15-minute period. The bottle was rotated at 60 r.p.m. during the run. A pyrolysis temperature of 660°C. and system pressure of 50 //, were employed. A total of 51.97 grams of encapsulated pellets was recovered at the end of the run. 

TRIFLUOROMETHYLPHENYL) ESTER see TKJ250 ISOCYANIC ACID, p-XYLYLENE ESTER see XSS260 ISOCYANIDE see COI500 1-ISOCYANO-4-NITROBENZENE see IKH780 ISOCYANURIC ACID, DICHLORO- see DGN200 ISOCYANURIC ACID, DICHLORO-, POTASSIUM SALT see PLDOOO... 

H. Maruyama. Dichloro tetraflouro-(2,2 -paracyclopane, aprocess for manufacturing thereof and poly-a, a-difluoro-chloro-p-xylylene film prepared therefrom. US Patent 6 194620, assigned to Daisan Kasei Kabushiki Kaisha (Tokyo, JP), February 27,2001. 

The polymerization proceeds via living diradicals. Poly(/ -xylylene), poly(2-chloro-p-xylylene), and poly(2,5-dichloro-/>-xylylene) are produced commercially by direct polymerization of the monomer on the surface to be coated. The films, which have only slight gas and water vapor permeability, are mostly used to separate condensor plates. 

DPXC and DPXD. The economic pressure to control dimer costs has had an important effect on what is in use today (ca 1997). Attaching substituents to the ring positions of a [2.2]paracyclophane does not proceed with isomeric exclusivity. Indeed, isomeric purity in the dimer is not an essential requirement for obtaining isomeric purity, eg, monosubstituted monomer, in the pyrolysis. Any mixture of the four possible heteronuclearly disubstituted dichloro[2.2]paracyclophanes, will, after all, if pyrolyzed produce the same monomer molecule, chloro-p-xylylene [10366-09-3] (16) (Fig. 4). 

Sample Preparation. The preparation of PPV precursor is briefly shown in Figure 1. The synthesis of p-xylylene-bis(tetrahydrothiophenium chloride) monomer IV was according to the method of Lenz et al (7 7) 10 g dichloro-p-xylene (V, Tokyo... 

FIGURE 9.5 Polymerization of dichloro-di-p-xylylene to poly(p-chloroxylylene) (e.g. Parylene C). 

The other commercially available members of this gronp are Parylene C and Parylene D. Parylene C is poly-mono-chloro-para-xylylene. Parylene C offers significantly lower permeability to moisture and gases, such as nitrogen and oxygen, while retaining excellent electrical properties. Parylene D is poly-dichloro-para-xylene. Properties of Parylene N, C, and D are shown in Table P.3. 

The PET reactions of isobutylene(2-methylpropene) (21) in the absence of methanol have yielded a novel photochemical nucleophile-alkene combination aromatic substitution reaction. The solvent, acetonitrile, was found to act as a nucleophile and add to the alkene radical cation to give a distonic radical cation that subsequently adds to the 1,4-dicyanobenzene radical anion. Cyclization to the ortho position of the phenyl group leads to product formation. Two-colour, two-laser techniques have been used to study the photolysis of a, a -dichloro-o- or -p-xylene to yield xylylenes. ... 

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