Poly polymer purification

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. 

Poly(/V-vinylpyrrolidone) [9003-39-8] M (111.1) , crosslinked/25249-54-7/m >300. Purify it by dialysis, and freeze-drying. Also by precipitation from CHCI3 solution by pouring into ether. Dry it in a vacuum over P2O5. For the crosslinked polymer purification is by boiling for lOminutes in 10% HCl and then washing with glass-distilled water until free from Cl ions. Finally, Cl ions are removed more readily by... 

Molecular Weight. Measurement of intrinsic viscosity in water is the most commonly used method to determine the molecular weight of poly(ethylene oxide) resins. However, there are several problems associated with these measurements (86,87). The dissolved polymer is susceptible to oxidative and shear degradation, which is accelerated by filtration or dialysis. If the solution is purified by centrifiigation, precipitation of the highest molecular weight polymers can occur and the presence of residual catalyst by-products, which remain as dispersed, insoluble soHds, further compHcates purification. 

The purification of j8-poly(L-malic acid) from A o-basiae has been reported involving methanol precipitation of the polymer in the form of the Ca salt [5]. This is possible because a high concentration of CaCOs is present in the growth medium. Unfortunately, the polymer acid is not soluble in aceton thus missing an additional purification step. In our hands, purification of jS-poly(L-malate) from several Aureobasidiae strains was unsatisfactory because of low yields and resisting impurities. 

GPC proved to be a method extraordinarily well suited to the analysis and purification of 9-phenylcarbazole monodendrons, naturally branched polymers.12 Monodendrons up to generation four, molecular weight 16.6 kDa, were separated by GPC. Branching, introduced into bacterially produced poly(hydroxy butyrate) by co-polymerization with hydroxyvaleric acid, was analyzed by GPC in chloroform with on-line viscometry.13... 

These thermolysis reactions normally produce polymeric products, free of the cyclic analogs, in essentially quantitative yield and in sufficient purity to give satisfactory elemental analysis upon removal of the sHyl ether byproduct under vacuum. Final purification is generally achieved by precipitation of the polymer into a non-solvent such as hexane. With the exception of poly(diethylphosphazene) (2), which is insoluble in all common solvents (see below), the new polymers are readily soluble in CH CU and CHCU. In addition, the phenyl substituted compounds (3-6) are soluble in THF andvanous aromatic solvents. None of the polymers are water-soluble however, Me2PN]n (1) is soluble in a 50 50 water/THF mixture. 

The method consists of the retention by sorption of the porphyrins on poly (vinyl alcohol) (PVA) hydrogels. Poly (vinyl alcohol) (PVA) is selected as the polymer of choice for the purification of industrial and medical wastewaters due to its capacity to form physically crosslinked hydrogels with the advantages of non-toxic, non-carcinogenic and biodegradable properties. 

Most eukaryotic mRNA molecules have up to 250 adenine bases at their 3 end. These poly (A) tails can be used in the affinity chromatographic purification of mRNA from a total cellular RNA extract. Under high salt conditions, poly (A) will hybridize to oligo-dT-cellulose or poly(U)-sepharose. These materials are polymers of 10 to 20 deoxythymidine or uridine nucleotides covalently bound to a carbohydrate support. They bind mRNA containing poly (A) tails as short as 20 residues. rRNA and tRNA do not possess poly (A) sequences and will not bind. After washing the mRNA can be eluted with a low salt buffer. 

Recent interest has turned to nitrated cyclodextrin polymers (poly-CDN) for potential use in insensitive and minimum smoke producing propellants. The synthesis, purification and characterization of the following polymers was studied in detail ... 

The disadvantages of all biochemical routes is the lack of variable tacticity in the polymer and, even more important, the need for time-consuming purification. PHB materials of feasible properties are only achieved with high production costs. In the 1990s, ICl sold a copolymer of 3-HB and 3-HV (BIOPOL) for about 10-20 /kg whereas the price of PP was less than 2 /kg. Therefore, a fermentative synthesis is feasible for smaller applications but not cannot compete with packaging materials such as poly(olefin)s [43 5] (Fig. 10). 

The conventional techniques for the purification of low-molecular-weight compounds, such as distillation, sublimation, and crystallization, are not applicable to polymers. In some cases, it is possible to remove the impurities by cold or hot extraction of the finely powdered polymer with suitable solvents or by steam distillation. Separation of low-molecular-weight components from water-soluble polymers [e.g., poly(acrylic acid),poly(vinyl alcohol), poly(acryl amide)]... 

Many other polymeric systems are of interest in polymer LEDs. Polythiophenes have been known for some time but it was not until improved synthetic methods were developed that their potential was realised. The process involves the reaction of the substituted monomer with FeClj in chloroform solution. After polymerisation has occurred the product precipitates and is isolated and washed. Further special purification methods are required to obtain satisfactorily pure materials. One product, of commercial interest, developed by Bayer is poly(ethylenedioxy)thiophene, known as PEDOT (3.110). This product when doped with polystyrene sulfonate, sold as Baytron P, has been found to be effective as a conducting, hole-injecting layer on the ITO electrode. ... 

Materials. Poly (olefin sulfone)s were prepared by copolymerization of liquid mixtures of sulfur dioxide and the appropriate olefin using tert.-butyl hydroperoxide as initiator in the temperature range from —80 to 0°C. The poly (amino acid)s were obtained from Sigma Chemical Co. and used without further purification. The poly (olefin) s were provided by Mr. O. Delatycki and Dr. T. N. Bowmer and were prepared under controlled conditions. The aromatic polysulfones were prepared and purified by Mr. J. Hedrick. The purity of all polymers was checked by H and 13C NMR. 

Poly(acrylamide) and its acrylic acid copolymers were obtained from polymerization of the monomers in aqueous solution using ammonium persulfate/sodium bisulfite initiator following the procedure reported by Fong and Kowalski.5 Depending on the amount of initiator used, the average molecular weights of the polymers were between 6,000 to 50,000 as determined by gel permeation chromatography (GPC). Taurine (2-aminoethanesulfonic acid) and sodium formaldehyde bisulfite were purchased from Aldrich and used without purification. 

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