Synthesis,characterization, and comparison of self‐doped,doped, and undoped forms of polyaniline,poly(o‐anisidine), and poly[aniline‐co‐(o‐anisidine)]

Polyaniline (PANI), poly(o‐anisidine), and poly[aniline‐co‐(o‐anisidine)] were synthesized by chemical oxidative polymerization with ammonium persulfate as an oxidizing reagent in an HCl medium. The viscosities, electrical conductivity, and crystallinity of the resulting polymers (self‐doped forms) were compared with those of the doped and undoped forms. The self‐doped, doped, and undoped forms of these polymers were characterized with infrared spectroscopy, ultraviolet–visible spectroscopy, and a four‐point‐probe conductivity method. X‐ray diffraction characterization revealed the crystalline nature of the polymers. The observed decrease in the conductivity of the copolymer and poly(o‐anisidine) with respect to PANI was attributed to the incorporation of the methoxy moieties into the PANI chain. The homopolymers attained conductivity in the range of 3.97 × 10^?3 to 7.8 S/cm after doping with HCl. The conductivity of the undoped forms of the poly[aniline‐co‐(o‐anisidine)] and poly(o‐anisidine) was observed to be lower than 10^?5 J/S cm^?1. The conductivity of the studied polymer forms decreased by the doping process in the following order: self‐doped → doped → undoped. The conductivity of the studied polymers decreased by the monomer species in the following order: PANI → poly[aniline‐co‐(o‐anisidine)] → poly(o‐anisidine). All the polymer samples were largely amorphous, but with the attachment of the pendant groups of anisidine to the polymer system, the crystallinity region increased. The undoped form of poly[aniline‐co‐(o‐anisidine)] had good solubility in common organic solvents, whereas doped poly[aniline‐co‐(o‐anisidine)] was moderately crystalline and exhibited higher conductivity than the anisidine homopolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

A Pan Photoaffinity Probe for Detecting Active Forms of Matrix Metalloproteinases

A photoaffinity probe based on the scaffold of a potent broad‐spectrum phosphinic peptide inhibitor of matrix metalloproteinases (MMPs) has been developed. A photolabile diazirine group for covalent modification of MMP active forms was incorporated at the P₁′ position, and a tritium radioactive label for the sensitive detection of MMP covalent adducts by radioimaging was attached. The probe was characterized on seven catalytic domains of human MMPs (MMP‐2, ‐3, ‐8, ‐9, ‐12, ‐13 and ‐14) and was found to display nanomolar affinities towards this set of MMPs, covalently modifying them with crosslinking yields varying from 12 to 58 %, thus leading to highly sensitive detection of these MMPs. In a complex proteome complemented with four recombinant MMPs (MMP‐2, ‐9, ‐12 and ‐13), this probe enabled their simultaneous detection with a threshold of few femtomoles and low background labelling. Those properties should make this new pan‐activity‐based MMP probe a valuable tool for the detection of MMP active forms from biological fluids or tissue extracts.     

Oxidative Stability of Microencapsulated Kenaf Seed Oil Using Co-extrusion Technology

This study investigates the effect of microencapsulation (via co‐extrusion technology using high methoxyl pectin‐enhanced alginate as a shell formulation) on the storage stability and antioxidant properties of kenaf seed oil. Microencapsulated kenaf seed oil (MKSO) and unencapsulated oil were stored at 25 °C for 28 days and at 65 °C for 24 days. The oils were then subjected to stability and quality evaluation based on peroxide, p‐anisidine, and total oxidation values, conjugated diene and triene levels, thiobarbituric acid reactive substances, free fatty acids, total phenolic content, and the radical scavenging activity assays of 2,2‐diphenyl‐1‐picrylhydrazyl and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid). The results showed that there was a significant increase (p < 0.05) in oxidation and a significant decrease (p < 0.05) of antioxidant activity in the unencapsulated oil while oxidation changes generally occurred more slowly in MKSO. It was demonstrated that the current microencapsulation method is a feasible approach to enhance oxidative stability of kenaf seed oil.     

Stereoselective HDAC Inhibition from Cysteine‐Derived Zinc‐Binding Groups

A series of small‐molecule histone deacetylase (HDAC) inhibitors, which feature zinc binding groups derived from cysteine, were synthesized. These inhibitors were tested against multiple HDAC isoforms, and the most potent, compound 10 , was determined to have IC₅₀ values below 1 μM . The compounds were also tested in a cellular assay of oxidative stress‐induced neurodegeneration. Many of the inhibitors gave near‐complete protection against cell death at 10 μM without the neurotoxicity seen with hydroxamic acid‐based inhibitors, and were far more neuroprotective than HDAC inhibitors currently in clinical trials. Both enantiomers of cysteine were used in the synthesis of a variety of novel zinc‐binding groups (ZBGs). Derivatives of L ‐cysteine were active in the HDAC inhibition assays, while the derivatives of D ‐cysteine were inactive. Notably, the finding that both the D ‐ and L ‐cysteine derivatives were active in the neuroprotection assays suggests that multiple mechanisms are working to protect the neurons from cell death. Molecular modeling was employed to investigate the differences in inhibitory activity between the HDAC inhibitors generated from the two enantiomeric forms of cysteine.     

Identifying Unknown Enzyme–Substrate Pairs from the Cellular Milieu with Native Mass Spectrometry

The enzyme–substrate complex is inherently transient, rendering its detection difficult. In our framework designed for bisubstrate systems—isotope‐labeled, activity‐based identification and tracking (IsoLAIT)—the common substrate, such as S‐adenosyl‐l ‐methionine (AdoMet) for methyltransferases, is replaced by an analogue (e.g., S‐adenosyl‐l ‐vinthionine) that, as a probe, creates a tightly bound [enzyme ? substrate ? probe] complex upon catalysis by thiopurine‐S‐methyltransferase (TPMT, EC 2.1.1.67). This persistent complex is then identified by native mass spectrometry from the cellular milieu without separation. Furthermore, the probe's isotope pattern flags even unknown substrates and enzymes. IsoLAIT is broadly applicable for other enzyme systems, particularly those catalyzing group transfer and with multiple substrates, such as glycosyltransferases and kinases.     

Comparison of poly(o‐anisidine) and poly(o‐anisidine‐co‐aniline) copolymer synthesized by chemical oxidative method

In this study, poly(o‐anisidine) [POA], poly(o‐anisidine‐co‐aniline) [POA‐co‐A], and polyaniline [PANi] were chemically synthesized using a single polymerization process with aniline and o‐anisidine as the respective monomers. During the polymerization process, p‐toluene sulfonic acid monohydrate was used as a dopant while ammonium persulfate was used as an oxidant. N‐methyl‐pyrolidone (NMP) was used as a solvent. We observed that the ATR spectra of POA‐co‐A showed features similar to those of PANi and POA as well as additional ones. POA‐co‐A also achieved broader and more extended UV–vis absorption than POA but less than PANi. The chemical and electronic structure of the product of polymerization was studied using Attenuated Total Reflectance spectroscopy (ATR) and UV–visible spectroscopy (UV–vis). The transition temperature of the homopolymers and copolymers was studied using differential scanning calorimetry and the viscosity average molecular weight was studied by using dilute solution viscometry. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A Thioether‐Stabilized d‐Proline–l‐Proline‐Induced β‐Hairpin Peptide of Defensin Segment Increases Its Anti‐Candida albicans Ability

We report a β‐hairpin dual stabilizing strategy: a d ‐proline‐l ‐proline (d ‐Pro‐l ‐Pro) dipeptide as the nucleating turn, and a thioether tether as a side‐chain linkage at a precisely designed position to stabilize the β‐hairpin. This method was used to modify the C‐terminal β‐hairpin moiety of the plant defensin, pv‐defensin, in order to obtain a stabilized peptide with enhanced anti‐Candida albicans activity (MIC 84–3.0 μm ), high serum stability (50 % remaining after 48 h) and low hemolysis (<10 % at 152 μm ). This modified peptide penetrated the C. albicans cell membrane within 5 min and showed high activity against clinically isolated antibiotic‐resistant C. albicans and Candida glabrata strains.     

A highly selective electrochemical sensor for l‐tryptophan based on a screen‐printed carbon electrode modified with poly‐p‐phenylenediamine and CdS quantum dots

A new highly selective electrochemical sensor for the determination of l ‐tryptophan was proposed by modifying the surface of screen‐printed carbon electrodes (SPCEs). The surface of SPCE was firstly modified by electropolymerization of p‐phenylenediamine (PPD). The polymer film was then covalently linked with cysteamine capped cadmium sulfide quantum dots (Cys‐CdS QDs) by using glutaraldehyde (GA) as a cross‐linker resulted in an organic–inorganic hybrid composite film (QDs/GA/PPD/SPCE). The modified electrode was applied as a working electrode for detecting various amino acids. It was found that the modified electrode gave an electrochemical response selectively to l ‐tryptophan over other amino acids. The experimental parameters, including pH of solution, buffer types, electropolymerization cycles, scan rate, and accumulation time, were studied and optimized. The proposed sensor can be used to detect l ‐tryptophan with a low detection limit of 14.74 µmol L^?1 with good precision and the relative standard deviation less than 3.7%. The modified electrode was used to detect l ‐tryptophan in beverage samples and gave satisfactory recoveries from 91.9 to 104.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40356.     

Synthesis and dissociation of amine‐blocked diisocyanates and polyurethane prepolymers

Substituted N‐methylanilines are shown to act as blocking agents for toluenediisocyanate. N‐methylaniline‐, N‐methyl‐p‐anisidine‐ and N‐methyl‐p‐nitroaniline‐blocked toluene diisocyanates have been prepared and characterized by FTIR, ¹H NMR and ¹³C NMR spectroscopies, and nitrogen content analysis. A new method for determining the minimum deblocking temperature of the blocked isocyanate is described. The method has advantages in that it can be used to find the minimum deblocking temperature of even non‐volatile blocking agents. The minimum deblocking temperature of the adducts is found to be in the following order: N‐methyl‐p‐anisidine–TDI adduct < N‐methyaniline–TDI adduct < N‐methyl‐p‐nitroaniline–TDI adduct. The anilines exhibit the same trend when they block a polyurethane prepolymer prepared using polypropylene glycol of molecular weight 2000 g mol^?1 and tolylene‐2,6‐diisocyanate. The deblocking temperatures are lower in the case of blocked prepolymers than in the blocked adducts. The blocked adducts and prepolymers are reacted with pyromellitic dianhydride (PMDA) in dimethylpropylene urea (DMPU) and the evolution of carbon dioxide is monitored to study the completion of imidization. The reaction time is in accordance with the deblocking ability of the adducts. The regeneration of the blocking agent is confirmed by gas chromatography. © 2002 Society of Chemical Industry     

Incorporation of manganese complexes into xylanase: new artificial metalloenzymes for enantioselective epoxidation

Here we report the best artificial metalloenzyme to date for the selective oxidation of aromatic alkenes; it was obtained by noncovalent insertion of Mn^III‐meso‐tetrakis(p‐carboxyphenyl)porphyrin [Mn(TpCPP), 1 ‐Mn] into a host protein, xylanase 10A from Streptomyces lividans (Xln10A). Two metallic complexes—N,N′‐ethylene bis(2‐hydroxybenzylimine)‐5,5′‐dicarboxylic acid Mn^III [(Mn‐salen), 2 ‐Mn] and 1 ‐Mn—were associated with Xln10A, and the two hybrid biocatalysts were characterised by UV–visible spectroscopy, circular dichroism and molecular modelling. Only the artificial metalloenzyme based on 1 ‐Mn and Xln10A was studied for its catalytic properties in the oxidation of various substituted styrene derivatives by KHSO₅: after optimisation, the 1 ‐Mn ‐ Xln10A artificial metalloenzyme was able to catalyse the oxidation of para‐methoxystyrene by KHSO₅ with a 16 % yield and the best enantioselectivity (80 % in favour of the R isomer) ever reported for an artificial metalloenzyme.     

Surface modification of halloysite nanotubes with l‐lactic acid: An effective route to high‐performance poly(l‐lactide) composites

To improve the interfacial bonding between halloysite nanotubes (HNTs) and poly(l ‐lactide) (PLLA), a simple surface modification of HNTs with l ‐lactic acid via direct condensation polymerization has been developed. Two modified HNTs were obtained: HNTs grafting with l ‐lactic acid (l‐HNTs) and HNTs grafting with poly(l ‐lactide) (p‐HNTs). The structures and properties of l‐HNTs and p‐HNTs were investigated. Then, a series of HNTs/PLLA, l‐HNTs/PLLA and p‐HNTs/PLLA composites were prepared using a solution casting method and were characterized by polarized optical microscopy (POM), field scanning electron microscopy, and tensile testing. Results showed that l ‐lactic acid and PLLA could be easily grafted onto the surface of HNTs by forming an Al carboxylate bond and following with condensation polymerization, and the amounts of the l ‐lactic acid and PLLA grafted on the surface of the HNTs were 5.08 and 14.47%, respectively. The surface‐grafted l ‐lactic acid and PLLA played the important role in improving the interfacial bonding between the nanotubes and matrix. The l‐HNTs and p‐HNTs can disperse more uniformly in and show better compatibility with the PLLA matrix than untreated HNTs. As a result, the l‐HNTs/PLLA and p‐HNTs/PLLA composites had better tensile properties than that of the HNTs/PLLA composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41451.     

Targeting Cystalysin,a Virulence Factor of Treponema denticola‐Supported Periodontitis

Cystalysin from Treponema denticola is a pyridoxal 5′‐phosphate dependent lyase that catalyzes the formation of pyruvate, ammonia, and sulfide from cysteine. It is a virulence factor in adult periodontitis because its reaction contributes to hemolysis, which sustains the pathogen. Therefore, it was proposed as a potential antimicrobial target. To identify specific inhibitors by structure‐based in silico methods, we first validated the crystal structure of cystalysin as a reliable starting point for the design of ligands. By using single‐crystal absorption microspectrophotometry, we found that the enzyme in the crystalline state, with respect to that in solution, exhibits: 1) the same absorption spectra for the catalytic intermediates, 2) a close pK_a value for the residue controlling the keto enamine ionization, and 3) similar reactivity with glycine, L ‐serine, L ‐methionine, and the nonspecific irreversible inhibitor aminoethoxyvinylglycine. Next, we screened in silico a library of 9357 compounds with the Fingerprints for Ligands and Proteins (FLAP) software, by using the three‐dimensional structure of cystalysin as a template. From the library, 17 compounds were selected and experimentally evaluated by enzyme assays and spectroscopic methods. Two compounds were found to competitively inhibit recombinant T. denticola cystalysin, with inhibition constant (K_i) values of 25 and 37 μM . One of them exhibited a minimum inhibitory concentration (MIC) value of 64 μg mL^?1 on Moraxella catarrhalis ATCC 23246, which proves its ability to cross bacterial membranes.     

Defining the Potential of Aglycone Modifications for Affinity/Selectivity Enhancement against Medically Relevant Lectins: Synthesis,Activity Screening,and HSQC‐Based NMR Analysis

The emerging significance of lectins for pathophysiological processes provides incentive for the design of potent inhibitors. To this end, systematic assessment of contributions to affinity and selectivity by distinct types of synthetic tailoring of glycosides is a salient step, here taken for the aglyconic modifications of two disaccharide core structures. Firstly we report the synthesis of seven N‐linked‐lactosides and of eight O‐linked N‐acetyllactosamines, each substituted with a 1,2,3‐triazole unit, prepared by copper‐catalyzed azide–alkyne cycloaddition (CuAAC). The totally regioselective β‐D ‐(1→4) galactosylation of a 6‐O‐TBDPSi‐protected N‐acetylglucosamine acceptor provided efficient access to the N‐acetyllactosamine precursor. The resulting compounds were then systematically tested for lectin reactivity in two binding assays of increasing biorelevance (inhibition of lectin binding to a surface‐presented glycoprotein and to cell surfaces). As well as a plant toxin, we also screened the relative inhibitory potential with adhesion/growth‐regulatory galectins (total of eight proteins). This type of modification yielded up to 2.5‐fold enhancement for prototype proteins, with further increases for galectins‐3 and ‐4. Moreover, the availability of ¹⁵N‐labeled proteins and full assignments enabled ¹H,¹⁵N HSQC‐based measurements for hu‐ man galectins‐1, ‐3, and ‐7 against p‐nitrophenyl lactopyranoside, a frequently tested standard inhibitor containing an aromatic aglycone. The measurements confirmed the highest affinity against galectin‐3 and detected chemical shift differences in its hydrophobic core upon ligand binding, besides common alterations around the canonical contact site for the lactoside residue. What can be accomplished in terms of affinity/selectivity by this type of core extension having been determined, the applied combined strategy should be instrumental for proceeding with defining structure–activity correlations at other bioinspired sites in glycans and beyond the tested lectin types.     

Stability of horseradish peroxidase immobilized on different cinnamic carbohydrate esters

Four types of organic polymer were used to cover 3 mm diameter glass beads for subsequent use in immobilizing horseradish peroxidase (HRP). These supports were the totally cinnamoylated derivatives of D ‐glucosone (GSOCN), D ‐sorbitol (SOTCN), ethyl‐D ‐glucopyranoside (EGSCN) or inuline (INCN). In some assays, a partially cinnamoylated derivative, 2,3,4,6‐tetracinnamoyl‐D ‐glucopyranoside (GPSTCN) (obtained from the EGSCN derivative by hydrolysis in acidic medium) was used. Polymerization and cross‐linking of the derivatives obtained initially was carried out by irradiation in the ultraviolet region, where these polymers show the greatest degree of sensitivity. The enzyme was immobilized by adsorption to the support. Immobilized enzymatic activity varied with the incubation time used (2–21 h), depending on the chemical nature of the immobilization support. The affinity of HRP for H₂O₂ and 2,2′‐azinobis(3‐ethylbenzothiazolinesulfonic acid) (ABTS) was slightly lower in the case of the enzyme immobilized on the GSOCN, SOTCN and EGSCN derivatives than in the case of the soluble enzyme, as can be seen from the corresponding apparent kinetic constants ( and ). However, the affinity of HRP immobilized on the INCN derivative for these substrates was higher than that shown by the enzyme in solution. In turn, the enzyme immobilized on all the supports was more resistant than the soluble form to inactivation by H₂O₂ and by heat at neutral pH. When the stability and durability of the immobilized HRP were analysed, the cinnamoylated derivatives prepared were seen to function as suitable supports for immobilizing peroxidase and to be suitable for industrial application of the enzyme. Copyright © 2004 Society of Chemical Industry     

Design of a Highly Selective and Potent Class of Non‐planar Estrogen Receptor β Agonists

Selective activation of the estrogen receptor β (ERβ) could be a safe approach to hormone replacement therapy for both women and men, in contrast to the estrogens currently used for women which activate both ERβ and ERα, occasionally causing severe side effects. The selective ERβ agonist AC‐131 has shown efficacy in animal models of Parkinson’s disease and neuropathic pain. With the use of AC‐131 as template, herein we report the discovery, synthesis, and structure–activity relationship (SAR) study of a new class of dihydrobenzofurans as potent and selective ERβ agonists. The SAR was established by enantioselective synthesis, molecular modeling, and whole‐cell‐based functional assays. The most potent diastereomer, cis‐ 10 ‐SR, was shown to have an EC₅₀ value of <1 nM , potency 100‐fold higher than that of AC‐131. Even more interestingly, compound trans‐ 10 ‐SS exhibited 1000‐fold ERβ/ERα selectivity while still maintaining good potency (～10 nM ). In addition, trans‐ 10 ‐SS showed only partial agonist activity (30–60 % Eff.) toward ERα at 10 μM . This unprecedented selectivity could be rationalized by molecular modeling. Compound trans‐ 10 ‐SS appears to be the first molecule to take advantage of both conservative amino acid differences found in the α‐ and β‐faces of the binding cavities of ERα and ERβ.     

Synthesis and Biological Evaluation of Purine 2′‐Fluoro‐2′‐deoxyriboside ProTides as Anti‐influenza Virus Agents

2′‐Fluoro‐2′‐deoxyguanosine has been reported to have potent anti‐influenza virus activity in vitro and in vivo. Herein we describe the synthesis and biological evaluation of 6‐modified 2′‐fluoro‐2′‐deoxyguanosine analogues and their corresponding phosphoramidate ProTides as potential anti‐influenza virus agents. Whereas the parent nucleosides were devoid of antiviral activity in two different cellular assays, the 5′‐O‐naphthyl(methoxy‐L ‐alaninyl) ProTide derivatives of 6‐O‐methyl‐2′‐fluoro‐2′‐deoxyguanosine, 6‐O‐ethyl‐2′‐fluoro‐2′‐deoxyguanosine, and 2′‐deoxy‐2′‐fluoro‐6‐chloroguanosine, and the 5′‐O‐naphthyl(ethoxy‐L ‐alaninyl) ProTide of 6‐O‐ethyl‐2′‐fluoro‐2′‐deoxyguanosine displayed antiviral EC₉₉ values of ～12 μM . The antiviral results are supported by metabolism studies. Rapid conversion into the L ‐alaninyl metabolite and then 6‐modified 2′‐fluoro‐2′‐deoxyguanosine 5′‐monophosphate was observed in enzymatic assays with yeast carboxypeptidase Y or crude cell lysate. Evidence for efficient removal of the 6‐substituent on the guanine part was provided by enzymatic studies with adenosine deaminase, and by molecular modeling of the nucleoside 5′‐monophosphates in the catalytic site of a model of ADAL1, thus indicating the utility of the double prodrug concept.     

Physico‐chemical composition,fractionated glycerides and fatty acid profile of chicken skin fat

Skin is one of the several co‐products of chicken meat industries, considered as waste, being rarely utilized or underutilized. Brazil is the world leader in chicken exports (3.6 million tons) and the third largest producer with 10.9 million tons, from which 440 000 ton/year are residues. This work aimes at characterizing chicken skin fat (CSF), comparing it with soybean oil, a well‐known and abundant compound, evaluating the physico‐chemical composition, fractionated glycerides and fatty acid profile, searching for CSF use in interesterification reactions. For that, determination of peroxide and p‐anisidine values, as well as thiobarbituric acid, iodine, saponification, acidity, unsaponified matter and refraction indexes were accomplished, besides the glycerides fractionation, followed by FAME derivatization and identification by GC. The nutritional quality indexes were calculated from the lipid profile. CSF showed satisfactory quality due to low acidity (0.65 g oleic acid/100 g), peroxide (2.14 meq/kg), p‐anisidine (0.70 absorbance units/g) values, besides presenting high proportion of MUFA (40%). However, due to CSF low hypocholesterolemic/hypercholesterolemic value (HH = 2.72), it may be difficult to use it for nutritional purposes the way it is found, once it tends to increase cholesterol. CSF it is a promising residue for different purposes including interesterification reactions and biodiesel production.     

Synthesis and characterization of conducting copolymers from aniline and o‐anisidine in HCl solutions

Conducting poly(aniline‐co‐o‐anisidine) (PAS) films with different ratios of aniline units in the polymer chain were prepared by oxidative polymerization of different molar ratios of aniline and o‐anisidine in 1 M HCl using cyclic voltammetry. Due to the much higher reactivity of o‐anisidine, the structure and properties of PASs were found to be dominated by the o‐anisidine units. The polymerization of poly‐o‐anisidine and PASs followed zero‐order kinetics with respect to formation of the polymer (film thickness) and the autocatalytic polymerization of aniline was completely inhibited. In contrast to polyaniline, a decrease in the polymerization temperature was found to increase the amount of copolymer formed and its redox charge. The presence of aniline units in PASs led to a pronounced increase in the molecular weight and conductivity, and a decrease in the solubility in organic solvents. Repetitive charging/discharging cycles showed that PASs resist degradation more than polyaniline. Copyright © 2003 Society of Chemical Industry     

Aniline and some of its derivatives as corrosion inhibitors for nickel in 1 M HCl solution

The inhibiting action of aniline and some of its derivatives (o‐, m‐ and p‐anisidine) towards the corrosion behaviour of nickel in 1 M HCl solution has been studied using weight loss and polarization techniques. These compounds were found to retard the corrosion rate of nickel. At constant temperature, the corrosion rate decreases with increasing inhibitor concentration. On the other hand, at any inhibitor concentration, the increase in temperature leads to an increase in the corrosion rate. The activation energy, ΔE_a, the equilibrium constant, k, as well as the other thermodynamic parameters (ΔG, ΔH and ΔS) for inhibitor process were calculated and analysed. The inhibitor efficiencies calculated from both weight loss and polarization methods are in good agreement and were found to be in the order: p‐anisidine > o‐anisidine > m‐anisidine > aniline. The inhibitive action of these compounds was attributed to the adsorption of molecular species and their inhibitive efficiencies depend on the relative position of the  OCH₃ group in the aniline ring. © 1999 Society of Chemical Industry     

Synthesis and characterization of ABA type tri‐block copolymers derived from p‐dioxanone,L‐lactide and poly(ethylene glycol)

A series of triblock co‐polymers, consisting of a poly(ethylene glycol) (PEG) central block joined to two blocks of random p‐dioxanone‐co‐L ‐lactide copolymers were synthesized by ring‐opening polymerization of p‐dioxanone (PDO) and L ‐lactide (LLA) initiated by PEG in the presence of stannous 2‐ethylhexanoate catalyst. The resulting copolymers were characterized by various techniques including ¹H and ¹³C NMR and FTIR spectroscopies, gel permeation chromatography, inherent viscosity, wide‐angle X‐ray diffractometry (WAXD) and differential scanning calorimetry (DSC). The conversion of PDO and L ‐lactide into the polymer was studied various mole ratios and at different polymerization temperature from ¹H NMR spectra. Results of WAXD and DSC showed that the crystallinity of PEG macroinitiator was greatly influenced by the composition of PDO and L ‐lactide in the copolymer. The triblock copolymers with low molecular weight were soluble in water at below room temperature. © 2003 Society of Chemical Industry