Allyl esters molecular weights

ABA triblock copolymers, where A was PBd and B either PS or PMMA were prepared by the combination of ROMP and ATRP techniques [122], The PBd middle blocks were obtained through the ROMP of cyclooctadi-ene in the presence of l,4-chloro-2-butene or cis-2-butene-l,4-diol bis(2-bromo)propionate using a Ru complex as the catalyst. The end allyl chloride or 2-bromopropionyl ester groups were subsequently used for the ATRP of either styrene or MMA using CuX/bpy (X = Cl or Br) as the catalytic system (Scheme 50). Quantitative yields but rather broad molecular weight distributions (Mw/Mn higher than 1.4) were obtained. 

Another example is the palladium catalyzed allylic substitution of 3-phenyl-2-propenyl-carbonic acid methyl ester to yield iV-(3-phenyl-2-propenyl)morpho-line reported by Reetz, Kragl and co-workers. This reaction was performed in the presence of phosphino-terminated amine dendrimers [17, 18] loaded with Pd11 cations as shown in Scheme 10. For this particular dendrimer with a molecular weight of 10 212 g/mol, a retention of 0.999 per residence time [35] was estimated in a membrane reactor with a SELRO MPF-50 membrane. It must be noted that a very high retention is a prerequisite for a continuous operating system, since a small leaching of the dendrimer leads to an exponential decrease in the amount... 

The observed stoichiometrically imbalanced polymerization behavior is rationalized by involvement of olefin-Pd(O) complex 14, which leads to cascade bidirectional allylation. Thus, after the first allylation of 13, 14 selectively forms the allylpalladium(II) complex at the other allylic terminal. Therefore, the polymer end groups are always the malonic ester moiety even in the presence of excess 13, which would not terminate the polycondensation by the attack on both polymer end groups. This behavior is dependent on the ligand of the Pd(0) catalyst bis(diphenylphosphino)butane (dppb) is indispensable, and use of PPh3 results in low molecular weight polymer as expected by Carothers and Flory s basic principle [1-3]. 

Methyl methacrylate (Fig. 1-4) and methacrylonitrile (6-5) are allylic-type monomers that do yield high molecular weight polymers in free radical reactions. This is probably because the propagating radicals are conjugated with and stabilized to some extent by the ester and nitrile substituents. The macroradicals are... 

In the presence of benzoyl peroxide, allyl acetate gives poor yields of polymer of low molecular weight. The deuterium-labeled ester, CH CHCD2OAC, polymerizes 2 to 3 times as fast as the 01 dinary ester, and gives polymer of about twice the molecular weight. How do you account for these facts ... 

Only four allyl esters are of significant industrial importance as monomers for the production of homopolymers diethylene glycol bis(allyl carbonate), which, as CR-39, is widely used as a plastic spectacle lens material of exceptional clarity, scratch, abrasion, and impact resistance, and diallyl o- and m-phthalates, supplied commercially as soluble low-molecular-weight prepolymers. These prepolymers may be molded and subsequently cross-linked to give rigid plastic objects. 

The polymerization of allyl esters may suffer from the standpoint of practical applications because the resins formed usually have a low molecular weight, and are slow to form even in the presence of excesses of initiator at advanced temperatures. On the other hand, these same shortcomings make allyl ester polymers uniquely suitable for the study of the fine structure of the polymer. The... 

The polymerization of acrylic and vinyl esters generally proceeds quite rapidly, with relatively low levels of initiators, to form products of considerable molecular weight. By contrast, allyl esters polymerize slowly with high levels of... 

With purified resin, alcohol decreases the interphase tension, with the exception of OP-10 (allyl phenol oxyethylated ester) for which it produces some increase (by ImN/m) [12]. These findings can be explained by the fact that the alcohol facilitates desorption of the low-molecular weight resin fractions with surface-active properties from the boundary between the resin and the mercmy by increasing their compatibility with the bulk resin. The free energy advantage for alcohol adsorption on the mercury surface is less than that for low-molecular weight fractions, which is why it results in increase of the interphase tension. 

Tris allyl phosphate, (CH2=CH-CH20)3P0, will give rise to a clear hard cross-linked polymer, although polymerised allyl or vinyl phosphates (12.75) have not generally led to successful commercial products. Simple monoalkyl phosphates on heating (12.76) can be made to yield polyphosphate esters with molecular weights approaching a million. 

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