Polymers with molecular weight greater

Polymers with molecular weights greater then 10 Dalton can be dissolved, up to 20%, in DMF, THF, NMP and dimethylacetonitrile, and in particular in dimethyl sulfoxide. 

The host-guest complexation between 13 and 14a resulted in supramolecular polymers with molecular weights greater than 90,000 g mol" as obtained by... 

Vinylidene fluoride can also be polymerized without a catalyst (Table 5.38) to obtain low molecular weight polymers.l" The reaction takes place in the absence of air between 300°C and 500°C and 13.8-69 MPa. The products have low molecular weight and range in appearance Irom viscous liquid to hard and soft wax. Polyvinylidene fluoride with a molecular weight of up to 1000 dissolves in cold benzene, those with molecular weight between 1000 and 2000 dissolve in hot benzene, and polymers with molecular weight greater than 2000 are insoluble in hot benzene. 

Heterogeneous Catalytic Polymerization. The preparation of polymers of ethylene oxide with molecular weights greater than 100,000 was first reported in 1933. The polymer was produced by placing ethylene oxide in contact with an alkaline-earth oxide for extended periods (61). In the 1950s, the low yield and low polymerization rates of the eady work were improved upon by the use of alkaline-earth carbonates as the catalysts (62). 

Sodium poly(a-L-glutamate). It was washed with acetone, dried, dissolved in water and ppted with isopropanol at 5°. Impurities and low molecular weight fractions were removed by dialysis of the aqueous solution for 50h, followed by ultrafiltration through a filter impermeable to polymers of molecular weights greater the 10. The polymer was recovered by freeze-drying. [Mori et al. J Chem Soc, Faraday Trans I 2583 1978.]... 

Both, TFE and VDF may be copolymerized with suitable comonomers in order to obtain macromolecular materials with improved end-use properties. One fluori-nated monomer that was copolymerized under mild conditions (308 K and 9-11 MPa) was perfluoropropyl-vinylether (PPVE) (CF3CF2CF2OCF=CF2). The copolymer was obtained in the form of a free-flowing powder, with almost quantitative yields moreover, its composition could be altered by changing the molar ratio of the comonomers in the feed. Interestingly, chains were synthesized with molecular weights greater than that of the commercial product with a concentration of carboxylic acid or acid fluoride end groups similar to those detected in polymers prepared in CFCs [101],... 

In general, the adhesive strength of a polymer increases with molecular weights greater than 100,000. The molecule must have adequate length to allow chain interpenetration into the mucus layer. However, the size and conformation of the polymer molecule play an important role as well. ... 

Kaplan et al. [92] has demonstrated that HRP-mediated polymerization of polyphenols can be carried out in solution, emulsions or biphasic mixtures of buffer solution and isooctane. In the case of biphasic mixtures, polymers with molecular weights around 2 kDa were achieved with polydispersities about 2.0. These polymerizations were undertaken in an isooctane/buffer biphasic medium. The authors showed that higher molecular weight polymer and greater control over the poly-dispersity could be achieved if the reaction was carried out in a reverse micelle stabilized by a surfactant in water. 

Fluid-loss studies were conducted using a gas pressured filter apparatus. The partially degraded polymer solutions were filtered through specific pore size filters (Millipore MF 0.05 to 5.0 jm using a gas pressure of 1(X) psi. In addition to insoluble residues, the 0.05 pm filter retained polymer degradation products with molecular weights greater than 3.0 x 10 d. 

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