Poly production procedures

To overcome temperature dependence of classic emulsions and to improve reproducible droplet sizes and skin compatibility, polymeric emulsifiers like dimethicones tpoly(siloxanes)] [12], poly(acrylamidosulfonic) acids (AMP) [13] and hydrophobically modified poly(acrylates) with Ci2-side chains [14] were used over the last years to substitute common surfactants. These polymer stabilized emulsions show good stability, high skin compatibility, even with sensitive skin types, high oil compatibility and a simplified production procedure [15]. 

Membrane Sep r tion. The separation of components ofhquid milk products can be accompHshed with semipermeable membranes by either ultrafiltration (qv) or hyperfiltration, also called reverse osmosis (qv) (30). With ultrafiltration (UF) the membrane selectively prevents the passage of large molecules such as protein. In reverse osmosis (RO) different small, low molecular weight molecules are separated. Both procedures require that pressure be maintained and that the energy needed is a cost item. The materials from which the membranes are made are similar for both processes and include cellulose acetate, poly(vinyl chloride), poly(vinyHdene diduoride), nylon, and polyamide (see AFembrane technology). Membranes are commonly used for the concentration of whey and milk for cheesemaking (31). For example, membranes with 100 and 200 p.m are used to obtain a 4 1 reduction of skimmed milk. 

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). 

The two-step poly(amic acid) process is the most commonly practiced procedure. In this process, a dianhydride and a diamine react at ambient temperature in a dipolar aprotic solvent such as /V,/V-dimethy1 acetamide [127-19-5] (DMAc) or /V-methy1pyrro1idinone [872-50-4] (NMP) to form apoly(amic acid), which is then cycHzed into the polyimide product. The reaction of pyromeUitic dianhydride [26265-89-4] (PMDA) and 4,4 -oxydiani1ine [101-80-4] (ODA) proceeds rapidly at room temperature to form a viscous solution of poly(amic acid) (5), which is an ortho-carboxylated aromatic polyamide. 

Tsuda156 reported the preparation of poly(vinyl 2-furylacrylate) by the reaction of 2-furylacrylyl chloride with poly(vinylalcohol) in NaOH-water-methyl ethyl ketone. Up to 80% of the hydroxyl groups were esterified. The interest of this technique is obvious here, considering that the vinyl ester of 2-furylacrylic acid does not polymerize119 A similar procedure was employed by Gandini and Rieumont26,1 9 for the synthesis of poly(vinyl 2-furoate) another product unobtainable via a standard polymerization process (see Section 1II-B-3). 

Soluble poly(l-butylperylene) (58) was prepared in very high yields by Anton and Mullen [70] who used the procedure of Taylor [71], which involves the oxidative coupling of bis-Grignard reagents with as-l,4-dichloro-2-butene as an oxidant. The products contain 4,9- and 4,10-perylenylene moieties, are fully soluble and possess average degrees of polymerization of ca. 22. 

Synthesis. Graft copolymer was formed in aqueous solution by ceric-ion-initiated, radical polymerization of monomer on starch. Polymerization was conducted in an inert, atmosphere. Details of the synthesis procedure may be found in references 41 to 43 In recovering the polymer product, freeze drying was used with care since freeze drying produces a more dissolvable and useful product but can degrade polymers with molecular weights of 1 million or more. Poly(starch-g-(1-amidoethylene)) Poly(starch-g-(1-amidoethylene))... 

The second step is the thermal conversion of borylaminoborazine into poly(borylaminoborazine). Continuous elimination of parent alkylamine is the main by-product dining the thermal polycondensation of 2,4,6-trialkylaminoborazine (see earlier). We expected the continuous elimination of the starting 5-alkylam i noborane during the thermal polycondensation of borylborazine. However, the alkylami noborane is a liquid, which requires that the thermal polycondensation must be performed in vacuo to continuously remove the evolving B(NHR)3 from the reaction mixture. This procedure also precludes any competing polycondensation reaction from B(NHR)3. 

A method for microwave-assisted transesterifications has been described by Van-den Eynde and Rutot [73], The authors investigated the microwave-mediated deriva-tization of poly(styrene-co-allyl alcohol) as a key step in the polymer-assisted synthesis of heterocycles. Several /i-ketoesters were employed in this procedure and multigram quantities of products were obtained when neat mixtures of the reagents in open vessels were subjected to microwave irradiation utilizing a domestic micro-wave oven (Scheme 7.65). The successful derivatization of the polymer was confirmed by IR, 1H NMR, and 13C NMR spectroscopic analyses. The soluble supports... 

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