Pendant Ester Groups Research Articles

Synthesis of a new amino acid/sulfur dioxide copolymer and its use in aqueous two‐phase polymer systems

AbstractThe amine salt N,N‐diallyl‐N‐5‐carbomethoxypentylammonium chloride was copolymerized with sulfur dioxide in dimethyl sulfoxide with ammonium persulfate or 2,2′‐azobisisobutyronitrile and afforded a cationic polyelectrolyte (CPE) with a five‐membered cyclic structure on the polymeric backbone. The CPE, upon acidic hydrolysis of the pendent ester groups, gave a corresponding cationic acid salt (CAS) having the equivalent of chloride salt of 6‐N,N‐diallylammoniohexanoic acid as the monomeric unit. The CAS was converted into an anionic polyelectrolyte (APE) and a polybetaine (PB), having the monomeric unit equivalent of sodium 6‐N,N‐diallylaminohexanoate and 6‐N,N‐diallylammoniohexanoate, by treatment with 2 and 1 equiv of base, respectively. The solution properties of APE were investigated by potentiometric and viscometric techniques. The basicity constant of the amine functionality in APE was apparent and as such followed the modified Henderson–Hasselbalch equation; the protonation of the APE became more and more difficult as the degree of protonation of the whole macromolecule increased. The compositions and phase diagrams of the aqueous two‐phase systems of APE and poly(ethylene glycol) were studied. The PB was found to be insoluble in water, and this paves the way for the potential use of APE in aqueous two‐phase polymer systems for protein purification and its removal and recycling by conversion into PB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2464–2477, 2002

Living cationic polymerization route to poly(oligooxyethylene carbonate) vinyl ethers

AbstractThe addition of dialkyl (R = Me or Et) carbonates to poly(oxyethylene)‐based solid polymeric electrolytes resulted in enhanced ionic conductivities. Relatively high conductivities in lithium batteries with solutions of lithium salts in di(oligooxyethylene) carbonates such as R(OCH2CH2)nOC(O)O(CH2CH2O)mR (R = Et, n = 1, 2, or 3, m = 0, 1, 2, or 3) and related carbonates were obtained. In this respect, related comb‐shaped poly(oligooxyethylene carbonate) vinyl ethers of the type CH2CH(OR) were prepared [R = (OCH2CH2)nOC(O)O(CH2CH2O)mR′; (1) n = 2 or 3, m = 0, R′ = Et; (2) n = 2 or 3; m = 3, R′ = Me]. The direct preparation of derived target polymers of this class by polymerization of the corresponding vinyl ether‐type monomers could not be achieved because of a rapid in situ decarboxylative decomposition of these monomers (as formed) during the final step of their synthesis. Instead, a prepolymer was prepared by a living cationic polymerization of CH2CH(OCH2CH2)nOC(O)CH3 (n = 2 or 3). The hydrolysis of its pendant ester groups, followed by the reaction of the hydrolyzed prepolymer with each of several alkyl chloroformates of the type ClC(O)O(CH2CH2O)mR′ (m = 0, 2, or 3, R′ = Me or Et) resulted in the corresponding target polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2171–2183, 2002

Synthesis and solution properties of a new pH-responsive polymer containing amino acid residues

The amine salt, N, N-diallyl- N-carboethoxymethylammonium chloride was cyclopolymerized in water using ammonium persulfate as an initiator to afford a cationic polyelectrolyte which on acidic hydrolysis of the pendant ester groups gave the corresponding cationic acid salt (CAS). The CAS was converted into an anionic polyelectrolyte (APE) and polybetaine (PB). The solution properties of the APE having two basic functionalities were investigated in detail by potentiometric and viscometric techniques. Basicity constants of the amine as well as the carboxylate groups in APE are ‘apparent’ and as such follow the modified Henderson–Hasselbalch equation; as the degree of protonation ( α) of the whole macromolecule increases, the protonation of the amine nitrogens and carboxylate groups becomes increasingly more difficult and easier, respectively. While the APE, PB and CAS were found to be soluble in salt-free water, the corresponding PB and CAS of the SO 2 copolymers of the amine salt 1 were found to be insoluble in water.

2,4-dihydroxy-1,3-bis(methoxycarbonylmethoxy)calix[4]arene and 1,3-bis(ethoxycarbonylmethoxy)-2,4-dihydroxycalix[4]arene chloroform solvate.

The two title calix[4]arene compounds, C34H32O8, (I), and C36H36O8*CH3Cl, (II), respectively, which differ only in the size of the alkyl function on the pendant ester group, are compared. Compound (I) forms a novel supramolecular array, whilst (II) fails to do so due to accommodating a chloroform guest molecule in the lower-rim cavity.

Synthesis and solution properties of a new ionic polymer and its behavior in aqueous two-phase polymer systems

The amine salt, N,N-diallyl-N-carboethoxymethylammonium chloride was copolymerized in dimethyl sulfoxide using ammonium persulfate or azo-bis-isobutyronitrile (AIBN) to afford the cationic polyelectrolyte (CPE) having five-membered cyclic structure on the polymeric backbone. The CPE on acidic (HCl) hydrolysis of the pendent ester groups gave the corresponding cationic acid salt (CAS) having the equivalent of chloride salt of N,N-diallylammonio ethanoic acid as monomeric unit. The CAS was converted into an anionic polyelectrolyte (APE) and polybetaine (PB) [having the monomeric unit equivalent of sodium N,N-diallylaminoethanoate and N,N-diallylammonioethanoate] by treatment with two and one equivalent of base, respectively. The solution properties of APE were investigated by potentiometric and viscometric techniques. Basicity constant of the amine functionality in APE is found to be ‘apparent’ and as such follow the modified Henderson–Hasselbalch equation; the protonation of the APE becomes more and more difficult as the degree of protonation (α) of the whole macromolecule increases. The composition and phase diagram of the aqueous two-phase systems of APE and poly(ethyelene glycol) (PEG) has been studied for the first time for this class of ionic polymers. The CAS and PB were found to be virtually insoluble in water.

Synthesis and characterization of oligomeric silsesquioxane with pendent carboxylic acid groups

An oligomeric silsesquioxane with pendent carboxylic acid groups and with supposedly ladder structure was prepared by preaminolysis process followed by the controlled hydrolysis of pendent ester groups. A variety of characterization techniques including 1 H-NMR, 29 Si-NMR, FTIR, vapour pressure osmosis, X-ray diffraction, and DSC demonstrated the structure of the final product. The resulting oligomer exhibits excellent film-formability thanks to the formation of hydrogen-bonded network between the pendent carboxylic acid groups even though its molecular weight is low, which predicts its direct usage as coatings for a variety of purposes.

Synthesis and solution properties of a quaternary ammonium polyelectrolyte and its corresponding polyampholyte

The quaternary ammonium salt, N, N-diallyl- N-5-carbomethoxypentyl- N-methylammonium chloride (DACPMAC), on cyclopolymerization in aqueous solution using tert-butylhydroperoxide, afforded the polyelectrolyte poly(DACPMAC), having five-membered cyclic structure on the polymeric backbone, in excellent yield. The polyelectrolyte on acidic hydrolysis of the pendent ester groups gave the corresponding polyampholyte poly(DAMAH) having the equivalent of 6-( N, N-diallyl- N-methyl ammonio) hexanoate (DAMAH) as monomeric unit. The solution properties of these polymers as well as the polyelectrolyte, poly(DACMMAC), and its corresponding polyampholyte, poly(DAMAE), [having the monomeric unit equivalent of N, N-diallyl- N-carboethoxymethyl- N-methylammonium chloride (DACMMAC) and N, N-diallyl- N-methyl ammonio ethanoate (DAMAE)] are investigated by potentiometric and viscometric techniques. Basicity constants of the polyampholytes are found to be ‘apparent’ and as such follow the modified Henderson–Hasselbalch equation. While the protonation of the polyampholyte poly(DAMAH) becomes more and more difficult as the degree of protonation ( α) of the whole macromolecule increases, the polyampholyte poly(DAMAE), exhibits the reverse trend i.e. the protonation process becomes easier and easier with increasing α.

Dilational viscoelastic behaviors of homopolymer monolayers: surface light scattering analysis

This is to report a new set of viscoelastic analyses of common polymers that are surface active at the air/water interface (A/W). The materials are polyethers such as poly(ethyleneoxide) (PEO) and poly(tetrahydrofuran) (PTHF), and vinyl polymers with pendant ester groups such as poly(vinylacetate) (PVAc), poly(methylacrylate) (PMA), poly(methylmethacrylate) (PMMA) and poly( t-butylmethacrylate) (PtBMA). Experimentally the viscoelastic parameters are deduced from the propagation characteristics of spontaneously formed capillary waves obtained by surface light scattering in conjunction with surface pressure Π measurements by the Wilhelmy plate technique. The static features of polymer monolayers at A/W are delineated by the surface pressure dependence of the static dilational elasticity ε s. Two static limits are expected for the dependence, one being the good solvent condition and the other the theta condition. By sorting polymers according to their static features, these polymers fall into two groups, i.e. the good and poor solvent (not quite theta) groups. In this report, there is a clear correspondence between the static features and viscoelastic characteristics of these polymer monolayers, and each group has its own differentiative static and viscoelastic profiles. The polymer monolayers belonging to the good solvent condition exhibit a viscoelastic profile characterizable as nearly perfectly elastic behavior over a wide range of surface coverage from infinite dilution to Π≈4 mN m −1. In contrast, those polymer monolayers under poor solvent conditions, i.e. PMMA and PtBMA, show a viscoelastic profile of incompressible films with the dynamics approaching the limit of an infinite lateral modulus, ε*→∞.

Novel method for preparation of poly(benzoxazinone-imide)

A novel method was developed to prepare poly(benzoxazinone-imide) by the dealcoholization of poly(amide-imide), having pendent ethoxycarbonyl groups, which was prepared from poly(amide acid). The poly(amide acid) was prepared from the reaction of pyromellitic dianhydride and 4,4'-diamino-6-ethoxycarbonyl benzanilide. The curing behavior of the poly(amide acid) was monitored by DSC, which indicated the presence of two broad endotherms, one with maximum at 153 °C due to imide-ring formation and the other with maximum at 359 °C due to benzoxazinone-ring formation. The poly(amide acid) was thermally treated at 300 °C/1 h to get poly(amide-imide) with pendent ester groups, then at 350 °C/2 h to convert into poly(benzoxazinone-imide) by dealcoholization. Viscoelastic measurements of the poly(amide-imide) showed that the storage modulus dropped at about 280 °C with glass-transition temperature (T g ) at about 340 °C. The storage modulus of poly(benzoxazinone-imide), however, was almost constant up to 400 °C and no T g was detected below 400 °C. Also, the tensile modulus and tensile strength of the poly(benzoxazinone-imide was much higher than that of the poly(amide-imide). The 5% decomposition of poly(benzoxazinone-imide) film was at 535 °C, which reflects its excellent thermal stability. Also, poly(benzoxazinone-imide) showed more hydrolytic stability against alkali in comparison to polyimides.

Chemical Structure Effect of (Meth) Acrylic Ester Copolymers and Modified Poly (Etliylene-co-Vinyl Acetate) Copolymer on Paraffin Deposition Prevention in Crude Oil

ABSTRACT Acrylic and methacrylic esters copolymers in various compositions: were synthesized in order to study the chemical structure effect over their effectiveness as pour point reducers in crude oil. Copolymerization results data from octadecyl methacrylate, hexadecyl methacrylate with methyl methacrylate and octadecyl acrylate, hexadecyl acrylate with methyl acrylate revealed superior results for acrylate monomers compared to methacrylate ones. Copolymers of ethylene and vinyl acetate (EVA) containing 19, 31 and 40% of vinyl acetate were chemically modified aiming to improve their performance as pour point reducer in crude oil. Ester pendant groups were introduced in the copolymer main chains resulting in meaningful increase of their performance as additive.

Functionalized and degradable polymers of malic acid stimulate bone repair

A water soluble and hydrolysable polyester derived from malic acid has been synthesized by copolymerization of three different malolactonic acid esters. Functional pendant groups have been selected to interact with and protect heparin binding growth factors (HBGF). Three β-substituted β-lactones have been synthesized by using aspartic acid as a chiral precursor and benzyl, allyl and butyl alcohols in the formation of the ester pendant groups. The terpolymer has been subjected to three consecutive different chemical modifications. This modified terpolymer, able to induce new bone formation in an in vivo model, has the same property as carboxymethyl benzylamide sulfonate dextrans (CMDBS). Consequently, the distribution of the lateral functional groups is more essential than the glucidic nature of the backbone to acquire biological efficiency.

Characterization and preliminary evaluation of ester-modified technetium-99m SNS/S mixed ligand complexes as potential brain perfusion agents

Two novel [ 99mTc](SNS/S) mixed ligand complexes carrying a pendant ester function on the monothiolate coligand were synthesized. The corresponding oxorhenium and [ 99gTc]oxotechnetium complexes prepared at the macroscopic level and chemically characterized were used for structure assignment of [ 99mTc](SNS/S) complexes prepared at the nanomolar level. Enzymatic hydrolysis of the pendant ester group of [ 99mTc](SNS/S) mixed ligand complexes by esterase was investigated in vitro and compared with that of the ethyl cysteinate dimer, [ 99mTc]ECD. Preliminary biodistribution data in mice shows that the complexes are lipophilic and exhibit significant initial uptake in rodent brain.

Synthesis and structural characterisation of rhenium(V) oxo-thioether thiolate complexes with pendant ester or carboxylate groups

The preparation and characterisation of novel Re oxo-complexes derived from 2-oxo-1,4-dithiacyclohexane is reported. The direct reaction of [ReO 2py 4][Cl] with a cyclic thioester in water or methanol in presence of base resulted in the synthesis of the carboxylate complex [ReO(HL 1)(L 1)] ( 1) (HL 1 = SCH 2CH 2SCH 2COOH) and methyl ester rhenium complex [ReO(L 1)(L 2)] ( 2) (L 2 = SCH 2CH 2SCH 2COOMe) respectively. The ester complex was also prepared from [ReO 4] −, by using SnCl 2 as a reducing agent in methanolic solution at pH around 8. The complexes were characterised by IR, 1 H , 13 C NMR, FAB MS, crystallographic, and elemental analyses. The X-ray crystal structures of both 1 and 2 were determined by single crystal X-ray diffraction. In both complexes the coordination geometry around Re is pseudo octahedral and the carboxyl oxygen of the uncoordinated carboxylate or ester group is in an anti confirmation with respect to the oxo ligand.

Stereocontrolled polyol synthesis via CH insertion reactions of silicon tethered diazoacetates

The preparation and rhodium catalysed CH insertion reactions of (alkoxysilyl)diazoacetates are reported, leading to the diastereoselective synthesis of 3,4,5-trisubstituted l-oxa-2-silacyclopentanes. Reduction of the pendant ester group followed by oxidative CSi bond cleavage furnishes 1,2,4-triols.

Contribution of pendant ester group hydrolysis to the erosion of acrylic polymers in binders aimed at organotin-free antifouling paints

Specific polymeric material applications as bioactive molecules delivery systems involve a strictly controlled degradation of polymer matrixes. One possibility to obtain a zero-order kinetic for small molecules release consists in a simple hydrolysis of ester groups contained in the macromolecular structure. The chemical degradation can lead to the continuous surface erosion of the formulated resins without loss of their mechanical properties and to a permanent activity of the delivery systems. Hydrolysis is a very well-known reaction in the case of organic molecules containing ester groups. The mechanism seems to be more complicated when ester groups are located in macromolecular structures. With the aim of antifouling applications, acrylic acid polymers bearing lateral ester groups of different chemical structures (hydrophilic, hydrophobic, hydrolyzable) have been prepared, characterized, and immersed in water, at pH 8, and their hydrolysis has been studied. Experimental data display two parameters, at least, which must be taken into account: the reactivity of the ester groups toward hydrolysis and the hydrophilic/hydrophobic balance of the polymer. The susceptibility of the acrylic polymers to hydrolysis has been compared to the erosion characteristics of the corresponding films. The results confirm that hydrolysis is necessary to obtain a regular degradation of the films without loss of mechanical properties. A relationship has been observed between the characteristics of hydrolysis and erosion for each studied polymer.

Metal hydride mediated reduction of 3-(alkylthio)oxindoles containing other potentially reducible groups

The reduction of several 3-(methylthio)oxindoles bearing ester groups on the benzene ring has been studied. The reaction is very dependent on the substitution of the oxindole, and the position of the ester group. Deprotonation of the C3 center by the metal hydride is the major initial pathway. This deprotonation plays a role in the reduction of the pendant ester group. Ester groups ortho, and presumably para, to C3 are very difficult to reduce, reaction only occurring with excess LiAlH4 at elevated temperatures. Once reduction starts, it is very difficult to stop, with reduction of the ester to a methyl group being observed. When deprotonation at this center is blocked, ester reduction becomes straightforward and can be accomplished at room temperature with LiEt3BH. Keywords: oxindole, reduction, anion.

Amino acid based bioanalogous polymers. Synthesis of novel poly(urethane amide)s based on N,N′‐(trimethylenedioxydicarbonyl)bis(phenylalanine)

AbstractThe feasibility of synthesizing high‐molecular‐weight amino acid based bioanalogous polymers (AABBPs)‐poly(urethane amide)s (PUA) — via polycondensation (PC) of di‐p‐nitrophenyl ester of N,N′‐(trimethylenedioxydicarbonyl)bis(L‐phenylalanine) (3) with diamines or their derivatives under mild conditions in organic solvents was studied for the first time. A regular PUA (ηred = 1,53 dL/g) was obtained by PC of 3 with hexamethylenediamine. A dipeptide (Phe‐Phe) containing regular poly(ester urethane amide) (ηred = 0,58 dL/g) was synthesized by PC of 3 with p‐toluenesulfonic acid salt of bis(L‐phenylalanine) 1,4‐butylene diester. A tripeptide (Phe‐Lys‐Phe) containing PUA (ηred = 0,38 dL/g) with pendent ester groups was prepared via PC of 3 with N,N‐bis(trimethylsilyl)‐L‐lysine methyl ester. These novel AABBPs which may be considered as structural analogs of AB type bioanalogous polymers — conventional poly(amino acids) are of interest in enzymology, immunology, pharmacology, and biotechnology (as materials for biomedical applications).

Sodium Ion-Selective Electrodes Based on Dibenzo-16-crown-5 Compounds with Pendent Ester Groups

Selectivities of 21 dibenzo-16-crown-5 compounds with pendent ester groups for alkali metal, alkaline earth metal, and ammonium ions have been determined in solvent polymeric membrane electrodes. The ionophores include alkyl sym-R-dibenzo-16-crown-5-oxyacetates with R = hydrogen, linear alkyl, branched alkyl, fluoroalkyl, alkenyl, alkynyl, and phenyl groups. For lariat ethers with a hydrogen, linear alkyl group, or branched alkyl group attached to the ring carbon that bears the ester-containing side arm, the Na{sup +}/K{sup -} selectivity increases as the bulkiness of the geminal substituent is enhanced; whereas the Na{sup +}/Li{sup +} selectivity exhibits a weaker inverse relationship to the size of R. On the other hand, the Na{sup +}/K{sup +} and Na{sup +}/Li{sup +} selectivities are insensitive to variations in the size and shape of the ester alkyl groups. For eight of the lariat ether ester ionophores, very high Na{sup +}/Li{sup +} selectivities of 10{sup 3.8}-10{sup 3.9} are observed. 22 refs., 3 figs., 2 tabs.

Miscibility behavior of blends of poly(alkyl methacrylate)s with poly(p‐methylstyrene‐co‐methacrylonitrile)

AbstractThe miscibility behavior of various poly(p‐methylstyrene‐co‐methacrylonitrile) (pMSMAN)/poly(alkyl methacrylate)s blends was studied using differential scanning calorimetry. pMSMAN is miscible with poly(methyl methacrylate), poly(ethyl methacrylate), poly(n‐propyl methacrylate), poly(isopropyl methacrylate), and poly(n‐butyl methacrylate) over certain copolymer composition ranges, but is immiscible with poly(isobutyl methacrylate) and poly(n‐amyl methacrylate). The width of the miscibility window decreases with increasing size of the pendant ester group of the poly(alkyl methacrylate), and is wider than that of the corresponding poly(p‐methylstyrene‐co‐acrylonitrile) blend system. Various segmental interaction parameters are calculated using a binary interaction model. © 1995 John Wiley & Sons, Inc.

Characterization of the Network Structure o Epoxy Resins Cured with Active Esters

Abstract Epoxy resins cured with polyfunctional active esters have no pendant hydroxyl groups but pendant ester groups. Epoxy resins without hydroxyl groups are expected to have high electric resistance, low dielectric constant, and low hygroscopicity. In this paper, the thermal, viscoelastic, dielectric, and hygroscopic properties are described on the epoxy resins cured with active esters in comparison with those of the resins with pendant hydroxyl groups that are cured with conventional curing agents. The network structure of epoxy resins with pendant ester groups is much looser than that of the resins with pendant hydroxyl groups. This is attributed to the lack of hydrogen bonds and to steric hindrance and plasticization of more bulky ester groups in the resins cured with active esters.