Interpolymer complex formation between form I helical and form II helical poly(l-proline) and poly(carboxylic acids)

Interpolymer complex formations between Form II helical poly(l-proline) [PLP(II)] and Form I helical poly(l-proline) [PLP(I)] and poly(carboxylic acids) such as polyacrylic acid (PAA), atatic polymethacrylic acid (at-PMAA), and syndiotatic polymethacrylic acid (st-PMAA) have been studied by FT-IR, X-ray diffraction, and light scattering measurements. It was found that the interpolymer complexes were formed via hydrogen bonding. The helical PLP(II) formed polymer complex more favorably with PAA and at-PMAA having a disordered structure than with st-PMAA having a ordered structure. In contrast, the helical PLP(I) formed polymer complex more favorably with st-PMAA than with PAA and at-PMAA. In addition, PLP(II) helix was destroyed on the complexation with PAA and at-PMAA, but the PLP(II) helix was perserved on the complexation with st-PMAA. However, the PLP(I) helix was all perserved on the complexation with poly(carboxylic acids). These findings could be explained in terms of molecular conformation of the complementary polymers associated with the complex formation. Received: 4 March 1997/Revised: 21 April 1997/Accepted: 28 April 1997     

Interpolymer complexes of poly(acrylamide) and poly(N-isopropylacrylamide) with poly(acrylic acid): a comparative study

The interpolymer complexation, through successive hydrogen bonding, between poly(acrylamide) (PAAm) and poly(N-isopropylacrylamide) (PNiPAAm) with poly(acrylic acid) (PAA) in aqueous solution has been viscometrically and potentiometrically investigated. The stoichiometry of the complexes formed was determined. By comparing the strength of the two complexes the very important contribution of the hydrophobic interaction in their formation has been indicated.     

Thermal degradation of poly(2-methylphenylene oxide), poly(2,5-dimethylphenylene oxide) and poly(1,4-phenylene oxide)

Polyoxyphenylenes were obtained from phenol, 2-methylphenol, 2,5-dimethyl-phenol in oxidative polycondensations using dimethylpyridineCuCl complexes as catalysts. Samples of polymers from polycondensations were not completely linear as found by i.r. analysis. The m.s. and c.c.—m.s. analysis of degradation products of poly(2-methylphenylene oxide) (PMPO) and poly(2,5-dimethylphenylene oxide) (P2, 5DMPO) have shown that both polymers undergo Fries-type rearrangement prior to statistical scission of benzyl bonds. Ether linkages of poly(1,4-phenylene oxide) (PPO) decompose without rearrangement though cyclization to benzofurane systems has been observed.     

Formation of interpolymer complexes between poly(monoethyl itaconate) and poly(N-vinyl-2-pyrrolidone)

This paper reports on the interpolymer complex formation and polymer blends between poly(monoethyl itaconate) (PMEI) and poly(N-vinyl-2-pyrrolidone) (PVP). The formation of the interpolymer complex was found to depend upon the solvent medium. Stoichiometry of the complexes prepared from methanol solutions, as calculated from elemental analysis, is close to 1 : 1. Specific interactions of PMEI/PVP complexes and blends of these polymers have been characterized by FTIR. Strong hydrogen bonding for complexes and blends has been found. A calorimetric study of the complexes and blends has been performed over a wide temperature range.     

Synthesis and characterization of complexes between poly(itaconic acid) and poly(ethylene glycol)

Summary Interpolymer complexes of poly(itaconic acid) and poly(ethylene glycol) (PIA/PEG) were prepared by two different procedures: simple mixing of preformed PIA and PEG and by polymerization of itaconic acid on poly(ethylene glycol) as a template. Complex formation was attributed to hydrogen bond formation between the carboxyl group of PIA and the ether group of PEG. The two types of complexes were characterized by viscometric measurements, thermogravimetric analysis (TGA), Fourier-transform infrared (FTIR) spectroscopy and adhesive force measurements. The results indicate that complexes prepared by template polymerization have a stronger hydrogen bonding and hence more ordered structure and better mucoadhesive properties.     

Influence of solvent on thermodynamic parameters and stability of some multicomponent polymer complexes involving an acrylic polymer,poly (ethylene imine) and poly (vinyl pyrrolidone)

Summary Stability constant and thermodynamic parameters (e.g. ΔH⁰ and ΔS⁰) have been determined at several temperatures for some multicomponent complexes of varying composition involving poly (acrylic acid) (PAA), poly (vinyl pyrrolidone) (PVP) and poly (ethylene imine) (PEI) in aqueous medium and water-DMSO mixture. It has been observed that the stability constant and thermodynamic parameters of the interpolymer complexes change due to presence of organic solvent in the medium. Some of these observations have been attributed to the change in the degree of solvation of component polymers, reduced hydrophobic interaction and dielectric constant of the medium.     

Density functional complexation study of metal ions with poly(carboxylic acid) ligands. Part 1. Poly(acrylic acid) and poly(α-hydroxy acrylic acid)

We have studied metal ion complexation with poly(carboxylic acid) ligands using density functional methods and a continuum-solvation model (COSMO). Geometry optimisations have been carried out for metal complexes of poly(acrylic acid-co-maleic acid), poly(methyl vinyl ether-co-maleic acid), and poly(epoxy succinic acid) oligomers. The complexation energies for Mg²⁺, Ca²⁺, Mn²⁺, and Fe³⁺ have been calculated and they have been corrected with previously determined metal specific correction parameters. The most effective ligand for all the metal ions was found to be poly(epoxy succinic acid). With Ca²⁺, poly(epoxy succinic acid) was found to form 6-coordinated complex with three metal-coordinating carboxylate oxygen, two ether oxygens, and one hydroxyl oxygen atom. All the other metals favoured 5-coordinated complexation geometry with four metal-coordinating carboxyl oxygens and one ether oxygen atom.     

Star-shaped poly(lactic acid) with carboxylic acid terminal groups via poly-condensation

A series of star-shaped poly(lactic acid)s with carboxylic acid terminal groups have been synthesized by direct poly-condensation of lactic acid in the presence of a poly-carboxylic acid core molecule with triphenylphosphonium trifluoromethanesulfonate (TPP-T) catalyst.These star-polymers had thermal properties not very much different from those of star-shaped poly(lactic acid) with hydroxyl terminal groups and linear poly(lactic acid), irrespective of the structure of the core molecule and number of polymer arms. Solubility and degradability of these star-polymers were, however, greatly enhanced compared to those of star-polymers with hydroxyl terminal groups and increased depending on the number of polymer arms. From the star-shaped polymers, a variety of ammonium salts and the corresponding carboxyamides were successfully prepared.     

Synthesis and characterization of poly(lactic acid) based graft copolymers

This review summarizes recent developments in the preparation and characterization of grafting of poly(lactic acid) or polylactide (PLA). PLA is the most expansively researched and utilized biodegradable, biocompatible, compostable, recyclable and renewable thermoplastic polyester. The graft copolymers of PLA have been synthesized and characterized by different spectroscopic techniques, including FTIR spectra and NMR data. The graft copolymers of PLA have been analyzed critically by taking different monomers/polymers; such as chitosan, cellulose, starch, polyethylene glycol, vinyl based polymers, lignin, dextran, methyl methacrylate, maleic anhydride and graphene oxide. In the first part of this review, the grafting of PLA and applications of grafted PLA has been discussed briefly. The second part, the major objective of this paper, focuses on the synthesis and characterization of different PLA based graft copolymers. For few cases, where useful properties, such as high molecular weight, narrow PDI, or stereocontrol, have been observed, a more detailed examination of the graft copolymers is provided.     

Infrared spectroscopy and electrical properties of ternary poly(acrylic acid)–metal–poly(acrylamide) complexes

Fourier transform infrared spectroscopy (FTIR) and electrical measurements were used for the characterization of the interpolymer complexation between poly(acrylic acid) (PAA) and poly(acrylamide) (PAAm) and also the ternary PAA–metal–PAAm complexes. The interpolymer complexes were prepared by adjusting the pH value of the mixture solutions at different PAA weight fractions (W_PAA). The ternary complexes were prepared by mixing metal chloride solutions (such as ErCl₃ and LaCl₃) with different concentrations to PAA–PAAm mixtures and adjusting the pH value for different W_PAA. It was found that the IR spectra of the interpolymer complexes showed absorption bands at shifted positions and of intensities different from those of the parent polymers. Also, the examination of the spectra of the ternary metal–polymer complexes revealed that they depend on the nature, lency, ionic radius, and concentration of the added metal chlorides. Analysis of the electrical results showed that the electrical conductivity of the interpolymer complexes are always lower than those of PAA and PAAm, which was attributed to the decrease in the mobility of the polymer chains as a result of the complexation. Also, the conductivity of the ternary metal complexes showed a dependence on the properties of the additives and were found to decrease with increasing their concentrations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2699–2705, 2002     

Thermal properties of poly(N-maleyl glycine), poly(N-maleyl glycine-co-acrylic acid), and their metal complexes

The thermal properties of two water-soluble polymers; poly(N-maleyl glycine) and poly(N-maleyl glycine-co-acrylic acid) as well as their metal complexes with Co(II), Zn(II), Ni(II), Cu(II), Fe(III), Cd(II), Pb(II), and Hg(II) ions were investigated. The copolymer-metal ion complexes were obtained in aqueous phase by using the Liquid Phase Polymer-Based Retention (LPR) technique in conjunction with membrane filtration. The water-soluble P(MG) and P(MG-co-AA) are shown to be useful for the retention of different metal ions and their separation from elements not bound to the polymeric reagent. The thermal stability of the copolymer-metal ion complexes under nitrogen atmosphere at 20–500°C was also investigated. The complexes with different transition were characterized with FT-IR and thermogravimetry (TGA). From the TGA data the thermal decomposition temperature (TDT) and kinetic parameters such as activation energy (Ea) and reaction order (n) were determined. Received: 21 April 1998/Revised version: 16 July 1998/Accepted: 22 July 1998     

Template polymerization of sodium methacrylate onto poly(allylamine) hydrochloride

The radical polymerization in aqueous solution of sodium methacrylate in the presence of poly(allylamine) hydrochloride as a template was studied using dilatometry. The properties of the polyelectrolyte complexes resulting from these template polymerizations were investigated and compared with those of the poly(sodium methacrylate)/poly(allylamine) hydrochloride complexes obtained by simple mixing of the preformed polymers. The kinetic study provides evidence for the presence of a strong template effect and indicates that the polymerization occurs by a zip mechanism. The results of the different characterization analyses have shown that the complexes obtained by template polymerization have a more ordered structure than the complexes prepared by mixing the two polymers.     

Coating of carbon fibers with adhesion-promoting thin poly(acrylic acid) and poly(hydroxyethylmethacrylate) layers using electrospray ionization

Thin coatings of poly(acrylic acid) (PAA) and poly(hydroxyethylmethacrylate) (PHEMA) were deposited onto carbon fibers by means of the electrospray ionization (ESI) technique in ambient air. These high-molecular weight polymer layers were used as adhesion promoters in carbon fiber–epoxy resin composites. Within the ESI process, the carbon fibers were completely enwrapped with polymer in the upper 10 plies of a carbon fiber roving. As identified with scanning electron microscopy also shadowed fibers in a bundle as well as backsides of fiber rovings were pinhole-free coated with polymers (‘electrophoretic effect’). Under the conditions used, the layers have a granular structure. Residual solvent was absent in the deposit. PAA and PHEMA films did not show any changes in composition and structure in comparison with the original polymers as analyzed by X-ray photo-electron spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Single-fiber pullout tests of coated fibers embedded in epoxy resin showed significantly increased interfacial shear strength. It is assumed that chemical bonds between carbon fiber poly(acrylic acid) and epoxy resin contribute significantly to the improved interactions.     

Synthesis,characterization, and degradation of poly(ester-anhydride) for particulate delivery

A series of poly(ester-anhydride) from poly(lactic acid) and poly(sebacic acid) have been synthesized and characterized. Poly(lactic acid) of molecular weight 2,550 Da has been synthesized from pharmaceutical grade lactic acid. The copolymers are in the molecular weight range of 3,000-15,000 Da, with the higher molecular weights obtained for the polymers with higher sebacic acid content. With increase in sebacic acid content, the melting point is also found to increase. The polymers with 50% or more poly(sebacic acid) content melt between 80 and 84 °C. These polymers have been formulated into microspheres and their degradation studied. Due to their biodegradability and the flexibility to alter their degradation profile, they find a wide application in drug delivery.     

Interpolymer complexes between hydrophobically modified poly(methacrylic acid) and poly(N-vinylpyrrolidone)

The formation and structure of interpolymer complexes between amphiphilic multi-block copolymers—poly(dimethylsiloxane-N-vinylpyrrolidone) and poly(dimethylsiloxane-methacrylic acid)—were studied using potentiometric and conductometric titration, viscometry and fluorescence spectroscopy. The ratio of hydrophobic/hydrophilic groups in the copolymer and the molecular weight of each sequence were varied in order to establish the influence of these parameters on the interactions between the components. The complexation between pairs of block copolymers, of block copolymers and homopolymers as well as between homopolymer pairs was considered. The complexes were formed through the hydrogen bonding. They have a compact structure with a non-stoichiometric composition of pyrrolidone to methacrylic acid groups ratio around 0.6-0.7, with the exception of complexes formed between pairs of homopolymers and of copolymers with the shortest siloxane block. The difference between the new complexes and the ones formed from homopolymers, with equimolar composition, is explained by the spatial non-complementarity of the copolymers having a ‘flower-like’ structure in aqueous solutions.     

Thermal analysis of poly(1,3,4-oxadiazole-2,5 diyl-1,2-ethenediyl) and poly(1,4-phenylene-1,3,4-oxadiazole-2,5 diyl-1,2 ethendiyl)

Poly(1,3,4-oxadiazole-2,5-diyl-1,2-ethendiyl) and poly(1,4-phenylene-1,3,4-oxadiazole-2,5 diyl-1,2-ethenediyl) have been prepared by condensation polymerization using fuming sulfuric acid and different quantities of terephthalic acid (T), fumaric acid (F), and hydrazine sulfate (HS). Homopolymers of F and T and various copolymers of F:T have been prepared. The polymer structure was investigated by IR and visible-range spectra and elemental analysis. The existence of poly(1,3,4-oxadiazole-diylphenylene) and poly(hydrazoterephthaloyl) structures was revealed by these studies. These polymers were thermally stable, and most of them did not show a weight loss below 350°C. The relative thermal stabilities of the various polymers have been evaluated by “integral procedural decomposition temperature” and activation energy measurements.     

On the cytotoxicity of poly(4-aminodiphenylaniline) powders: Effect of acid dopant type and sample posttreatment

Thanks to their unique properties, as intrinsic conductivity and simple preparation, conducting polymers are highly applicable in tissue engineering, regenerative medicine, and biosensors. Pristine polymers often include residual precursors or other low molecular impurities, which have a negative impact on their biocompatibility. Concerning poly(4-aminodiphenylaniline), its cytotoxicity and biocompatibility have not yet been investigated. Herein, the cytotoxicity of poly(4-aminodiphenylaniline), prepared by an innovative green approach, as well as the effect of samples’ posttreatment and kind of dopant acid used, are reported for the first time. The results show that not only the type of used dopant but also polymers’ washing in phosphate saline buffer and material’s morphology has a significant impact on materials’ cytotoxicity. After a proper posttreatment or when salicylic acid is used as the doping agent the cytotoxicity of poly(4-aminodiphenylaniline) seem to be lower than those obtained for traditional PANI.     

Viscosimetric study of poly(vinyl alcohol)/poly(styrenesulfonic acid) miscibility in dilute aqueous solution

The miscibility of poly(vinyl alcohol) (PVA) and poly(styrenesulfonic acid) (PSSA) in dilute aqueous solutions was studied by a viscosimetric method. At a constant molecular weight of PSSA, it was found that the miscibility of both polymers increases with the molecular weight and the number of acetate groups of the PVA samples (1 and 12% unhydrolyzed sites). Moreover, this miscibility increases slightly with the total mixture concentration in the interval 1–2 g/dL. By comparison of the results of reduced viscosity of PVA/PSSA and PVA/poly(sodium styrenesulfonate) (PSSNa) mixtures, it has been deduced that the miscibility of two polymers is due mainly to intermolecular interactions between the hydroxyl and sulfonic groups of PVA and PSSA, respectively. These groups act as acceptors and donors of hydrogen bonds which are the responsible for polymers' miscibility. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of coordination polymers of Hg(II) with poly(thiooxamides)

Coordination polymers of Hg(II) with dithiooxamide, poly(ethylene thiooxamide), poly(butane thiooxamide), and poly(hexane thiooxamide) have been synthesized. All coordination polymers are solid compounds insoluble in common organic solvents. Coordination polymers have been characterized by elemental analysis, IR spectra, and thermogravimetric analysis and structures have been proposed leading to coordination of metal through S alone as well as N and S both. Thermal stability of the polymers has also been discussed.     

Kinetics and reaction mechanism of template polymerization investigated by conductimetric measurements. Part 3. Radical polymerization of acrylic acid in the presence of poly(N‐vinylpyrrolidone)

Conductimetry was used for monitoring the radical polymerization of a weak electrolyte (acrylic acid) in aqueous solution and for determination of the kinetic parameters of the reaction (reaction order with respect to monomer, activation energy). The results obtained were consistent with those determined by other techniques (such as dilatometry) or expected from theory. Dilatometric and conductimetric measurements were also used to study the template polymerization of acrylic acid onto poly(N‐vinylpyrrolidone). Results indicate that the reaction proceeds according to a pick‐up mechanism. Complexes between poly(acrylic acid) and poly(N‐vinylpyrrolidone) were always isolated in equimolar composition of the two polymers, regardless of the polymerization mixture composition. Spectroscopic evidence of the existence of strong interaction and intimate mixing of the two polymers in the complexes was found. An influence of the template molecular weight on the chain length of the forming poly(acrylic acid) was detected by means of viscometry. © 2000 Society of Chemical Industry