Poly ethyl ester

The earliest study describing vulcanised polymers of esters of acryUc acid was carried out in Germany by Rohm (2) before World War I. The first commercial acryUc elastomers were produced in the United States in the 1940s (3—5). They were homopolymers and copolymers of ethyl acrylate and other alkyl acrylates, with a preference for poly(ethyl acrylate) [9003-32-17, due to its superior balance of properties. The main drawback of these products was the vulcanisation. The fully saturated chemical stmcture of the polymeric backbone in fact is inactive toward the classical accelerators and curing systems. As a consequence they requited the use of aggressive and not versatile compounds such as strong bases, eg, sodium metasiUcate pentahydrate. To overcome this limitation, monomers containing a reactive moiety were incorporated in the polymer backbone by copolymerisation with the usual alkyl acrylates. 

D-ChiraSpher Poly[(S)-lV-acryloylphenylalanine ethyl ester] [11,23,86] Merck... 

A series of poly(ester-urethane) urea triblock copolymers have been synthesized and characterized by Wagner et al/ using PCL, polyethylene glycol, and 1,4 diisocyanatobutane with either lysine ethyl ester or putrescine, as the chain extender. These materials have shown the elongation at break from 325% to 560% and tensile strengths from 8 to 20 MPa. Degradation products of this kind of materials did not show any toxicity on cells. 

A polynucleoside with an unnatural polymeric backbone was synthesized by SBP-catalyzed oxidative polymerization of thymidine 5 -p-hydroxyphenylacetate. Chemoenzymafic synthesis of a new class of poly(amino acid), poly(tyrosine) containing no peptide bonds, was achieved by the peroxidase-catalyzed oxidative polymerization of tyrosine ethyl esters, followed by alkaline hydrolysis. Amphiphile higher alkyl ester derivatives were also polymerized in... 

Table 2 contains the characteristics of the amic ester-aryl ether copolymers including coblock type, composition, and intrinsic viscosity. Three series of copolymers were prepared in which the aryl ether phenylquinoxaline [44], aryl ether benzoxazole [47], or aryl ether ether ketone oligomers [57-59] were co-re-acted with various compositions of ODA and PMDA diethyl ester diacyl chloride samples (2a-k). The aryl ether compositions varied from approximately 20 to 50 wt% (denoted 2a-d) so as to vary the structure of the microphase-separated morphology of the copolymer. The composition of aryl ether coblock in the copolymers, as determined by NMR, was similar to that calculated from the charge of the aryl ether coblock (Table 2). The viscosity measurements, also shown in Table 2, were high and comparable to that of a high molecular weight poly(amic ethyl ester) homopolymer. In some cases, a chloroform solvent rinse was required to remove aryl ether homopolymer contamination. It should also be pointed out that both the powder and solution forms of the poly(amic ethyl ester) copolymers are stable and do not undergo transamidization reactions or viscosity loss with time, unlike their poly(amic acid) analogs.

Poly(amIc ethyl ester) block copolymer Processable/soluble Intermediate... 

Merck ChiraSpher Helical Poly(bi-acryloylphenylaIanine ethyl ester)... 

Ester synthesis of fatty acid ethyl ester. The lipase-catalyzed esterification of fatty acid and alcohol is well-known. It was also favorable for the esterification of poly unsaturated fatty acids under mild conditions with the enzyme. However, the activity of native lipase is lower in polar organic solvents, i.e. ethanol and methanol. The synthesis of Ae fatty acid ethyl ester was carried out in ethanol using the palmitic acid-modified lipase. As shown in Figure 7, the reactivity of the modified lipase in this system was much higher than that of the unmoditied lipase. 

It became of interest to see if we could obtain any indication of Schiff base formation with the polymer. Since spectroscopic probes would be obscured with the actual substrate, oxalacetate, because of the progress of the decarboxylation reaction (32), we have examined instead the spectra of oxalacetate-4-ethyl ester in solutions of the same modified poly-(ethylenimine) PEIQ—NH2. Such solutions develop a new absorption band at 290 nm. Furthermore, this band is essentially abolished if NaBH4 is added to the solution (Fig. 21). As is well known, NaBH4 reduces Schiff base linkages to amine groups.43-44... 

It has also been possible to confirm the presence of the reduction product of a Schiff base on the polymer by proton magnetic resonance. For this purpose we have used unmodified poly(ethylenimine), since it too catalyzes the decarboxylation of oxalacetate to its product, pyruvate. Unmodified polyethylenimine was mixed with oxalacetate-4-ethyl ester. One-half of this solution was treated with NaBH4 the second half was exposed to a similar environment but no NaBH4 was added. The borohydride-treated polymer exhibited a strong triplet in the nmr spectrum centered at 3.4 ppm upfield from the HOD resonance. This new feature would be expected from the terminal methyl protons of the oxalacetate ester attached to the polymer. Only a very weak triplet was found in the control sample not treated with borohydride. These observations are strong evidence for the formation of Schiff bases with the polymer primary amine groups. Evidently the mechanistic pathway for decarboxylation by the polymer catalyst is similar to that used enzymatically. 

FIGURE 11.5 Degradation of N-a-benzoyl-l-arginine ethyl ester by trypsin. All three carboxyl containing polymers have antitrypsin activity, but the activity of trypsin in the presence poly(ethylene glycol) modified poly(methacrylic acid) is not greatly reduced. (Adapted from Madsen and Peppas 1999.)... 

Particularly noteworthy are the tyrosine-derived polycarbonates (27), a family of polymers based on alkyl esters of desaminotyrosyl-tyrosine. The lead polymer in this family is poly[desaminotyrosyl-tyrosine ethyl ester (DTE) carbonate], a polymer derived from desaminotyrosyl-tyrosine ethyl ester. Other polymers in this series of tyrosine-derived polycarbonates are poly[desaminotyrosyl-tyrosine butyl ester (DTB) carbonate], poly[desaminotyrosyl-tyrosine hexyl ester (DTH) carbonate], and poly [desaminotyrosyl-tyrosine octyl ester (DTO) carbonate], where the letters B, H, and O indicate the presence of butyl, hexyl, or octyl ester pendent chains, respectively. 

Fig. 6. Solution viscosity of para-PM DA/ODA poly(amic ethyl ester) in N-methylpyrrolidone at 27 °C. ( ) with pyridine ( ) without pyridine...

In addition to the nature of the ester group, the structural isomerism of the polymer backbone also exerts some effect on the imidization characteristics [82]. Thus, for PMDA/ODA poly(amic ethyl ester) the pure para-isomer was found to imidize at slightly lower temperatures as compared to the pure metaisomer, see Fig. 10. This result is consistent with the report the amide groups exhibiting para-catenation represent the more favorable conformation for cyclization as determined for poly(amic acids) [83]. Results consistent with the... 

Fig. 11. Elongation-at-break as a function of precursor molecular weight for polyimides derived from ( ) poly(amic acid) and ( ) polyfamic ethyl ester)...

The chemical imidization of poly(amic alkyl esters) was only reported very recently [59], although reports in the literature claim chemical imidization with a traditional acetic anhydride/pyridine mixture [87]. The chemical imidization of poly(amic alkyl esters) is based on the observation that PMDA/ODA based poly(amic ethyl ester) samples, when formulated at low concentrations for size exclusion chromatography, precipitated upon standing overnight [88]. Distillation of the NMP from phosphorus pentoxide to remove low levels of methyl-amine, a known impurity in this particular solvent, eliminated this unusual behavior. The precipitated polymer had significant levels of imidization as evidenced by IR. Apparently, organic bases, such as alkyl amines, were able to catalyze the conversion of amic alkyl esters to the corresponding imide. 

Table 9. Degree of imidization of poly(amic ethyl esters) in the presence of diethylamine...

Poly(amic ethyl ester-co-aryl ether phenylquinoxaline)... 

Meldal and coworkers developed polyacrylamides cross-linked with poly(ethylene glycol), referred to as PEGA, as supports for solid-phase synthesis and on-bead enzymatic assays [181-183]. Functionalization of the polymer was performed in a similar fashion as in the case of other polyacrylamides, i.e. either by copolymerization with N-acryloylsarcosine ethyl ester followed by aminolysis with ethylenediamine, or by copolymerization with an amino group containing monomer. The monomers used for a high-capacity (0.4-0.8 mmol/g [182]) and a low-capacity (0.2-0.4 mmol/g [181]) PEGA support are sketched in Figure 2.7. 

Poly-N-[l-carbetoxy-3-methyl-butyl]-acrylamide (XXVIII) has been prepared from poly-acrylyl-chloride (XXIX) and leucine ethyl ester (XXX) ([a]f)° + 13.1) according to Scheme 5. 

Cham warp dyeing -for poly(ethyl acrylate) [ACRYLIC ESTER POLYMERS - SURVEY] (Vol 1) -polymerization of acrylamide [ACRYLAMIDE POLYMERS] (Vol 1) -for poly(methyl methacrylate) [METHACRYLIC POLYMERS] (Vol 16)... 

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