Poly polymerization solvents

Polymerization Solvent. Sulfolane can be used alone or in combination with a cosolvent as a polymerization solvent for polyureas, polysulfones, polysUoxanes, polyether polyols, polybenzimidazoles, polyphenylene ethers, poly(l,4-benzamide) (poly(imino-l,4-phenylenecarbonyl)), sUylated poly(amides), poly(arylene ether ketones), polythioamides, and poly(vinylnaphthalene/fumaronitrile) initiated by laser (134—144). Advantages of using sulfolane as a polymerization solvent include increased polymerization rate, ease of polymer purification, better solubilizing characteristics, and improved thermal stabUity. The increased polymerization rate has been attributed not only to an increase in the reaction temperature because of the higher boiling point of sulfolane, but also to a decrease in the activation energy of polymerization as a result of the contribution from the sulfonic group of the solvent. 

Polylactides, 18 Poly lactones, 18, 43 Poly(L-lactic acid) (PLLA), 22, 41, 42 preparation of, 99-100 Polymer age, 1 Polymer architecture, 6-9 Polymer chains, nonmesogenic units in, 52 Polymer Chemistry (Stevens), 5 Polymeric chiral catalysts, 473-474 Polymeric materials, history of, 1-2 Polymeric MDI (PMDI), 201, 210, 238 Polymerizations. See also Copolymerization Depolymerization Polyesterification Polymers Prepolymerization Repolymerization Ring-opening polymerization Solid-state polymerization Solution polymerization Solvent-free polymerization Step-grown polymerization processes Vapor-phase deposition polymerization acid chloride, 155-157 ADMET, 4, 10, 431-461 anionic, 149, 174, 177-178 batch, 167 bulk, 166, 331 chain-growth, 4 continuous, 167, 548 coupling, 467 Friedel-Crafts, 332-334 Hoechst, 548 hydrolytic, 150-153 influence of water content on, 151-152, 154... 

Preparation of nanoparticles can be by a variety of different ways. The most important and frequently used is emulsion polymerization others include interfacial polymerization, solvent evaporation, and desolvation of natural proteins. The materials used to prepare nanoparticles are also numerous, but most commonly they are polymers such as poly-alklcyanoacrylate, polymethylmethacrylate, poly-butylcyanoacrylate, or are albumin or gelatin. Distribution patterns of the particles in the body can vary depending on their size, composition, and surface charge [83-85]. In particular, nanoparticles of polycyanoacrylate have been found to accumulate in certain tumors [86,87]. 

Although polymeric solvents have previously been prepared, they are usually based on pyridine, imidazole, or styrene and have the physical forms of a glass or a sticky rubber. Agents in the current application are liquids. Once dissolved poly(2-acrylamido-2-methyl-l-propanesulfonic acid) oxyethylene ammonium salts, however, can be directly converted into fabrics. 

Propagation of the polymerization occurs nearly exclusively by head-to-tail reactions, with only a small fraction of head-to-head reactions. The relative ratio of these two reactions is only a function of temperature and has been found to be independent of molecular weight, polymerization solvent, and method of polymerization. The head-to-head addition yields a 1,2-glycol structure in the resulting poly(vinyl alcohol), which in turn influences the degree of crystallinity, strength, solubility, and thermal stability. 

Carbomers are synthetic, high-molecular-weight, crosslinked polymers of acrylic acid. These poly(acrylic acid) polymers are crosslinked with allyl sucrose or allyl pentaerythritol. The polymerization solvent used most commonly was benzene however, some of the newer commercially available grades of carbomer are manufactured using either ethyl acetate or a cyclohexane-ethyl acetate cosolvent mixture. The Carbopol ETD resins are produced in the cosolvent mixture with a proprietary polymerization aid, and these resins are crosslinked with a polyalkenyl polyether. 

Poly(arylene thioether ketone)s have an excellent heat resistance, but they have poor heat stability upon melting (melt stabiUty). Poly(arylene thioether ketone ketone)s, are not suitable for industrial production because particular polymerization solvents and monomers must be used." ... 

EFFECT OF POLYMERIZATION SOLVENT ON THE CHEMICAL STRUCTURE AND CURING OF AROMATIC POLY(AMIDEIMIDE)... 

A useful, hydrocarbon-soluble, dilithium initiator has been prepared by the dimerization of 1,1-diphenylethylene with lithium in cyclohexane in the presence of anisole (15 vol%) as shown in equations 14 and 15 (43). Although the initiator was soluble in this mixture, it precipitated from solution when added to the polymerization solvent (cyclohexane or benzene). Therefore, the dilithium initiator was chain extended with approximately 30 units of isoprene to generate the corresponding soluble oligomer. This initiator was used to prepare well-defined polystyrene-6ZocA-polyisoprene-6/oc -polystyrene and poly(a -methylstyrene)-6Zoc -polyisoprene-6ZocA-poly(o -methylstyrene) triblock copolymers with >90% 1,4-microstructure by sequential monomer addition. 

From the peak area ratios, it can be concluded that the Nb-derived polymer has an approximately 60% cis structure, whereas its Ta-derived counterpart has a 38% cis structure. It is postulated that NbCls provides poly[l-(trimethylsilyl)-l-propyne]s with higher cis content as compared to TaCls in a similar way to that in which Mo-based catalysts produce higher cis contents as compared to W-based catalysts. Provided that the same catalyst is used, the geometric structure of this polymer varies little with the polymerization temperature over a range of 30-100 °C, or with the polymerization solvent (e.g., cyclohexane, toluene, 1,2-dichloroethane, anisole). 

TnBP was also studied in a polymeric solvent, poly-(propylene glycol) (PPG) (91). The molecular weight of the PPG liquids were 400, 1000 and 2000. Contrary to expectation, the solute and solvent motions were well-separated with (solute) being about 30 times larger than Te(solvent) As a result, two distinct dielectric loss peaks were obtained. The Kerr-constant of PPG was very small in comparison with that for TnBP so the Kerr-effect rise and decay transients were essentially due to solute. Figure 9 shows the derived plot of logfjn - vs - (T/K) l for solute and solvent processes. 

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