Molecular weight polymer from

The synthesis of the high molecular weight polymer from chlorotrifluoroethylene [79-38-9] has been carried out in bulk (2 >—21 solution (28—30), suspension (31—36), and emulsion (37—41) polymerisation systems using free-radical initiators, uv, and gamma radiation. Emulsion and suspension polymers are more thermally stable than bulk-produced polymers. Polymerisations can be carried out in glass or stainless steel agitated reactors under conditions (pressure 0.34—1.03 MPa (50—150 psi) and temperature 21—53°C) that require no unique equipment. 

With as httie as 0.5% hydrolysis of the sulfone monomer, the polymerization stoichiometric balance is sufficientiy upset to prevent high molecular weight polymer from being achieved. The dependence of maximum attainable PSF molecular weight on water content during polymerization can be inferred from Figure 1. 

A common theme in the speculated polymerization reactions discussed in this section is that the polymers were generally uncharacterized or were composed of small cyclic oligomers. No evidence for high molecular weight polymers from low-coordinate phosphorus compounds was obtained. Of course, multiple bond formation, not polymerization, was the focus of these studies. 

FIGURE 20 Rate of metabolism of PCL and its metabolites, determined from measurement of carbon-14 in the excreta and exhaled air of rats after implantation (s.c.) of the low molecular weight polymer. (From Ref. 53.)... 

Figure 6. Assignment of resonances in C-13 NMR spectrum of low-molecular-weight polymer from 2,4,6-trichlorophenoxide...

Poly(arylenethioether phenylquinoxaline)s have been prepared from the reaction of a bis(chloroquinoxaline) compound with 4,4 -dimercaptodiphenyl ether [19]. The polymer of structure 4 had an unusually high intrinsic viscosity of 4.0 dL/g, a Tg of 243 °C and good solubility in NMP and chloroform. The greater nucleophilicity of the thiophenolate anion versus the phenolate anion allowed the formation of high molecular weight polymer from the... 

Diethyizinc is not an active catalyst for polymerization of ethylene oxide and propylene oxide, but gives a high molecular weight polymer from styrene oxide (78) and a copolymer from styrene oxide and propylene oxide (79). This behavior is interpreted by assuming that styrene oxide easily reacts with diethyizinc to give a catalytically active species Zn[OCH2CH PhEt]2 (79,80). 

Using activated manganese dioxide, silver oxide, or lead dioxide as the oxidizing agents, McNelis has also obtained low molecular weight polymer from 2.6-dimethylphenol (60, 61). 

The synthesis of block copolycondensates by condensation reactions has also been described very often indeed the ineluctable presence of reactive end groups makes these molecules especially suitable for reactions with dibasic acids, diisocyanates, diacid chlorides, diamines, diols, etc. Using this method it was for example possible to synthesize polycondensates in which crystalline blocks alternate with amorphous blocks similarly it makes possible the synthesis of high molecular weight polymers from polycondensates of relatively low degree of polymerization. 

Addition of cuprous chloride to these prepolymers in a DMAc/pyri-dine solution and subsequent oxygenation led to the formation of high molecular weight polymers from which strong, elastic and hot-drawable... 

Ring-opening metathesis polymerization (Problem 26.28) An olefin metathesis reaction that forms a high molecular weight polymer from certain cyclic alkenes. 

The importance of these catalysts stems from the fact that they are the only ones known which will give high molecular weight polymers from olefins such as propene and butene-1, and with these and other monomers the polymers have specific molecular configurations [8]. (It has been appreciated for some years that monomer units could be disposed in a polymer chain in various stereochemical arrangements [9], but before the discovery of coordination catalysts there was little expectation, with the possible exception of the dienes, that the polymer structure could be varied or controlled by the choice of initiator.)... 

When the polycarbonate of bisphenol A was made interfacially in a non-solvent for the polymer the distribution of molecular weights showed two clear maxima and was unusually broad [40]. This was probably a consequence of the two-step process often employed in the preparation of polycarbonates here, the first step yields low-molecular-weight polymer from phosgene and the aqueous alkaline solution of the aromatic diol, then an accelerator salt and more alkali and phosgene are added in the second step. Polycarbonates prepared in the melt and in solution show the expected essentially statistical distribution of molecular weights [40]. Polycarbonates have also been prepared from bisphenols and bisphenol bischloroformates studies of this reaction in nitrobenzene solution have shown it to be second order [79]. 

As already mentioned, the polymerization of 1,3,5-trioxane and bicyclic acetals (including anhydro sugars) is discussed separately. In this section we shall only give the conditions for preparation of high-molecular-weight polymers from the parent monomer of this class 1,3-dioxolane (DXL). The majority of conclusions applies also to the 7-membered acetal 1,3-dioxepane (DXP). 

Macrocyclization is one of the processes that limits the preparation of high-molecular-weight polymers from both cyclic sulfides and some cyclic amines. The mechanism of cationic macrocyclization is discussed in detail in Chap. 3. 

Hydrolysis of polymers derived from 2-substituted monomers requires strong alkaline conditions and the yield does not exceed 90 % 27). However, high-molecular-weight polymer from 2-phenylOXL was converted to linear polyEI using 35% HC1 at 100 °C after 5 days38). 

Sophorolipids are extracellular glycolipids that can be produced in high yields from yeast fermentation. Waller et al (57) carried out metathesis reactions to produce high molecular weight polymers from sophorolipids. Another example of the use of polysaccharide is the paper by Jong (P), where carbohydrates are incorporated in polymer composites. 

Though it has been reported that some acetylenes having OH and COOH groups can be polymerized by group 6 and 8 transition-metal catalysts, it is rather difficult to obtain soluble, high molecular weight polymers from them 9,i60 Ethynylthiophenes show a polymerizability similar to that of phenylacetylene 9,196 studies on the polymeriza-... 

Metal alkyls and metal alcoholates are very effective anionic initiators for higher aldehydes. Aldol condensation can occur, however, in the presence of strong bases. Thus, while some such initiators yield high molecular weight polymers from formaldehyde, they only yield low molecular weight polymers from higher aldehydes. Initiations by metal alkyls result from additions to the carbonyl group ... 

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