Polymeric esters

Poly(acrylic acid) and Poly(methacrylic acid). Poly(acryHc acid) (8) (PAA) may be prepared by polymerization of the monomer with conventional free-radical initiators using the monomer either undiluted (36) (with cross-linker for superadsorber appHcations) or in aqueous solution. Photochemical polymerization (sensitized by benzoin) of methyl acrylate in ethanol solution at —78° C provides a syndiotactic form (37) that can be hydrolyzed to syndiotactic PAA. From academic studies, alkaline hydrolysis of the methyl ester requires a lower time than acid hydrolysis of the polymeric ester, and can lead to oxidative degradation of the polymer (38). Po1y(meth acrylic acid) (PMAA) (9) is prepared only by the direct polymerization of the acid monomer it is not readily obtained by the hydrolysis of methyl methacrylate. 

Group of plastics composed of resins based on saturated polymeric esters whereby the recurring ester groups are an integral part of the primary polymer chain and the ester groups exist in cross-links that are present between chains. 

Group of plastics composed of resins derived principally from polymeric esters that have recurring polyester groups in the main polymer chain. These polyester groups are crosslinked by carbon/carbon bonds. 

Therapeutic Function Estrogen Chemical Name Estradiol phosphate polymer Common Name Polymeric ester of phosphoric acid and estradiol Structural Formula r... 

Polylactide (PLA)-CaS04 composites toughened with low molecular weight and polymeric ester-like plasticizers and related performances. European Polymer Journal 44 3842-3852. 

Alkyl methacrylates, hydrolysis of polymeric ester functionality, 259 Aluminum-hydrogen bond, nucleophilic substitution, 264 Amines alkylation, 28 benzyl-group cleavage, 25 Aminomethylation chloromethylated polymers, 19 Deltfpine reaction, 19 Anionic polymerization advantages, 85... 

Polymeric esters by use of imidazolides or benzotriazolides have been obtained in different ways. 

If R is a polymeric ester, or ether, of molecular weight 1000-3000 a flexible elastic material will result. By reacting MDI and active hydrogen components (polyether/ester and a short chain glycol) in equivalent stoichiometric quantities, a linear polymer with virtually no crosslinks is obtained. 

The propagation by both types of modified ester probably involves a 6-centred cyclic transition state. The same applies to a third type of /-cat propagation, in which a polymeric ester reacts with a D-A complex formed from M + I2. 

Thermoset polymeric esters consisting of neopentyl glycol, propylene glycol, trimethylol propane, adipic acid, maleic anhydride, and 2-ethyl hexanol were prepared by McAlvin et al. (3) and were used in blends containing styrene monomer. The mixture was cured by pultrusion and had improved weatherabil-ity characteristics. 

Parallel work by Penczek and his co-workers (134) using esters of fluoro-methanesulphonic acid, e.g. Et-0S02CF3, to polymerise THF has shown that these initiators are more complex, polymerisations being characterised by a relatively slow initiation process. Rather interestingly, both kinetic data and independent 1HNMR studies indicate a further complication in that during polymerisation a polymeric ester species exists in equilibrium with a fully developed macroion. 

The anion generated by a Michael addition can also be trapped by another Michael addition. Obviously, continued repetition of this process produces polymeric esters, nitriles, etc., in a typical anionic poly-... 

Trapping of l-azetin-4-one as a dienophile was attempted by using some polymers functionalized with dienic groups, such as the 2-(polymeric carb-oxymethyl)-3-methyl-1,3-butadiene of the polymeric ester of 2-furoic acid, which have been good trapping agents for other dienophilic systems. Under several experimental conditions, both dienic polymers were recovered unchanged. 

Both intermediates (40) and (41) are able to act either as dienes or as dienophiles in the Diels-Alder reactions. The Diels-Alder reactions have been carried out by using polymeric monoester of acetylenedicaboxylic acid (42) as a dienophile trapping agent and polymeric ester of 2-furoic acid (23) as a dienic trapping polymer (81JA1797). 

After removal of barium sulfate and fractionation of the alkaloid salts, the glycol sulfate ester is recovered as alkali salt and saponified -with alkali.48, 48 The method is tedious and not yet well developed, but it may be noted that the glycols cannot be resolved by the phthalic ester procedure described below because they tend to form polymeric esters instead of simple hydrogen phthalates when treated with phthalic anhydride. 

The procedure usually is unsuitable for tertiary alcohols since the reaction with phthalic anhydride or succinic anhydride either fails or results in dehydration of the alcohol. A few tertiary alkyl phthalates, however, have been prepared and resolved by first converting the alcohols to sodium or potassium salts and allowing these to react79 80 with phthalic anhydride. This modification has been applied successfully to dUa- and /S-santalols81 and cB-linalool.81 As already mentioned, glycols cannot be resolved by this procedure because they form polymeric esters when heated with phthalic or succinic anhydride. Phenols also usually form phthaleins or other condensation products instead of simple acid esters. 

The solubility of the peptide is strongly enhanced by the polymeric ester group... 

For applications requiring high temperature and extraction resistance, polymeric esters are used (88). New polymeric plasticisers are in development (87) including adipate based for improved low temperature properties (103). Plastisols based on propyleneglycol adipate have been examined (198) and the thermal degradation has been determined using dynamic and isothermal thermogravimetric analysis (188). 

The scope of the living cationic polymerizations and synthetic applications of these functionalized monomers will be treated in the next chapter on polymer synthesis (see Chapter 5, Section III.B). One should note that the feasibility of living processes for these polar monomers further attests to the formation of controlled and stabilized growing species. Conventional nonliving polymerizations, esters, ethers, and other nucleophiles are known to function as chain transfer agents and sometimes as terminators. In addition, the absence of other acid-catalyzed side reactions of the polar substituents, often sensitive to hydrolysis, acidolysis, etc., demonstrates that these polymerization systems are free from free protons that could arise either from incomplete initiation (via addition of protonic acids to monomer) or from chain transfer reactions (/3-proton elimination from the growing end). 

---