Pseudo poly esters

Ester-Based "Pseudo" Poly(Amino Acids) 208 Poly(Amino Acids) 213... 

ESTER-BASED "PSEUDO" POLY(AMINO ACIDS)... 

Esters are the most common functional groups used to synthesize pseudo poly(amino acids) because of their well-characterized reaction schemes for condensation reactions and the availability of the multiple reactants and catalysts. Table 12.1 summarizes ester-based pseudo poly (amino acids). The presence of hydroxyl (on serine, threonine. 

TABLE 12.1 "Pseudo" Poly(amino acids) Formulated with Esters ... 

Carbonates (ester of carbonic acid) are functional groups in which the carbon atom is surrounded by three oxygen atoms. This structure consists of two single and one double bonds. Carbonate-based pseudo poly(amino acids) are the first bioactive polymers to be synthesized and have been reported initially by Kohn [40,41]. The molecular weights of these polymers range from 120 to 450 kDa [40,41]. Their... 

S. Mallakpour, F. Zeraatpisheh, Pseudo-poly(amino acid)s study on construction and characterization of novel chiral and thermally stable nanostructured poly(ester-imide)s containing different trimellitylimi-do-amino acid-based diacids and pyromellitoyl-tyrosine-based diol. Colloid Polym. Sci. 289 (2011) 1055-1064. 

Abstract A review is presented of the main types of bioresorbable or bioabsorbable materials used in medical applications such as drug delivery. Groups discussed include aliphatic polyesters, polyanhydrides, poly(ortho esters) (POE), polyphosphazenes, poly(amino acids) and pseudo poly(amino acids), polyalkylcyanoacrylates, poly(propylene fumarate) (PPF), poloxamers, poly(p-dioxanone) (PPDO) and polyvinyl alcohol (PVA). 

Another synthetic concept of polyamides includes the term pseudo-poly(amino acids). In this family of polymers belong naturally occurring amino acids linked by non-amide bonds. Tyrosine, serine and hydroxyproline-derived polymers with ester and iminocarbonate bonds in the chain have been investigated [446],... 

A, A, and A represented the absorbancies at initial time, at completion of the reaction, and at the time of measurement, respectively, k was considered to be a pseudo first-order rate constant defined by the expression -dc/dt = k C(C/C ), where C/Cq represents the relative reactivity of the ester groups on a pol3nner chain as a function of extent of reaction. A reasonably good fit to this was obtained for reactions conducted in the absence of catalysts as well as in those catalyzed by N-methyl-imidazole and poly-(N-vinylimidazole). 

Thermal decomposition of poly(vinyl acetate) results in a loss of acetic acid. The reaction is typical of thermal cleavages of esters. It is facilitated by formation of pseudo six-membered rings as a result of interactions between the p-hydrogens of the alcohol residues and the carboxylic groups ... 

The use of a high-molecular-mass surfactant (HMMS) or polymerized surfactant has been recently investigated as a pseudo-stationary phase in MEKC. Because a HMMS forms a micelle with one molecule, enhanced stability and rigidity of the micelle can be obtained. Also, it is expected that the micellar size is controlled easier than with a conventional low-molecular-mass surfactant (EMMS). The first report on enantiomer separation by MEKC using a chiral HMMS appeared in 1994, where poly(sodium N-undecylenyl-L-valinate) [poly(L-SUV)] was used as a chiral micelle and binaphthol and laudano-sine were enantioseparated. The optical resolution of 3,5-dinitrobenzoylated amino acid isopropyl esters by MEKC with poly(sodium (lO-undecenoyl)-L-valinate) as well as with SDVal, SDAla, and SDThr was also reported. 

These CD-based polymers were engaged in hydrolysis reaction of various p-nitrophenol esters derivatives. The reaction was monitored by UV at 400 mn. Among the CD-based polymers, only poly- 3-CD-A showed a high hydrolysis activity. The pseudo first-order rate constant k measured for the ester hydrolysis catalyzed by poly- 3-CD-A is compared to the rate constant measured using the native 3-CD. The rate enhancements resulting from the use of poly- 3-CD-A are presented in Table 2.1. 

The multicomponent ATRP system consists of an initiator (alkyl (pseudo)halide, RX), a redox-active transition metal in its lower oxidation state (M"), ligands, a deactivator (XM" species) and the monomer. ATRP is performed in bulk or in solution at elevated temperatures [288] with the possible use of different additives. One important item to regard is the fact that in ATRP one set of conditions cannot be applied to every monomer class. While neither polyacrylic nor poly(methacrylic) acid can be synthesized with currently available ATRP systems, because the monomers rapidly react with the metal complexes to form metal carboxylates, various acrylate esters can be polymerized by ATRP (Scheme 28) [289]. In analogy to these acrylate esters a wide range of methacrylate esters is expected to undergo ATRP. 

---