Addition of thiol-ended polystyrene to acrylates

Polystyrene containing end thiol groups has been prepared via the aminolysis or alcoholysis of its trithioester under conditions established previously for the model reaction of bis(1-phenylethyl) trithiocarbonate. The aminolysis of polystyrene with M _n = 8.2 × 10³ by n-hexylamine at 100°C in toluene led to the formation of a polymer with M _n = 4 × 10³ and a polydispersity coefficient of 1.13. The unimodal molecular-mass distribution of the polymer and its narrow polydispersity that is nearly equal to the initial polydispersity suggest that all trithiocarbonate groups of the starting polystyrene are involved in hydrolysis. The addition of 1-phenylethylthiol and thiol-ended polystyrene to methyl acrylate and methyl methacrylate via the Michael hydrolysis has been studied, and it has been demonstrated that the addition proceeds quantitatively at room temperature. The addition may be directly implemented with the use of dithioesters in the presence of the catalytic amount of a base; therefore, the stage of thiol synthesis can be eliminated. For the quantitative addition to acrylates, the preliminary hydrolysis of the polymer is however preferable.     

Molecular weight standards from sulfonation of polystyrene

Polystyrene was sulfonated with sulfur trioxide–triethyl phosphate complexes in dichloroethane, the object being to prepare polystyrene sulfonates substantially free of sulfone links between polymer chains. Variations in the sulfone content with reaction conditions were conveniently followed by exclusion chromatography, the sulfone peak appearing at about twice the molecular weight of the main peak. The desired products were obtained from polystyrenes with molecular weights between 1.1 × 10⁵ and 8.7 × 10⁵ by using (at ?20 to +25°C) a 5:1 excess of a 1.5:1 complex, the last at a concentration of 0.5M. Completely soluble polystyrene sulfonate was also obtained from polystyrene of molecular weight 2.05 × 10⁶. Requirements for the successful use of the 1.5:1 complex include careful purification of the dichloroethane and, if 2 g or more polystyrene is to be sulfonated, formation of the complex at ?20°C. A method is given for measuring the sulfonating capability of the reagent before adding the polymer.     

Synthesis and Characterization of a Water‐Soluble Carboxylated Polyfluorene and Its Fluorescence Quenching by Cationic Quenchers and Proteins

We have developed a new intermediate monomer, 2,7‐[bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)‐9,9‐bis(3‐(tert‐butyl propanoate))]fluorene, that allows the easy synthesis of water‐soluble carboxylated polyfluorenes. As an example, poly[9,9′‐bis(3′′‐propanoate)fluoren‐2,7‐yl] sodium salt was synthesized by the Suzuki coupling reaction, and the properties of the polymer were studied in aqueous solutions of different pH. Fluorescence quenching of the polymer by different cationic quenchers (MV²⁺, MV⁴⁺, and NO₂MV²⁺; MV=methyl viologen) was studied, and the quenching constants were found to be dependent on the charge and electron affinity of the quencher molecule and the pH of the medium. The largest quenching constant was observed to be 1.39×10⁸ M ^?1 for NO₂MV²⁺ at pH 7. The change in polymer fluorescence upon interaction with different proteins was also studied. Strong fluorescence quenching of the polymer was observed in the presence of cytochrome c, whereas weak quenching was observed in the presence of myoglobin and bovine serum albumin. Lysozyme quenched the polymer emission at low protein concentrations, and the quenching became saturated at high protein concentrations. Under similar experimental conditions, the polymer showed improved quenching efficiencies toward cationic quenchers and a more selective response to proteins relative to other carboxylated conjugated polymers.     

Metal Ion Removal from Aqueous Solution by Liquid Phase Polymer-Based Retention Technique

Summary: Water-soluble poly[3-(dimethylamino)propylacrylate] is synthesized by radical polymerization with a yield of 87%. The polymer structure is confirmed by FT-IR and ¹H-NMR spectroscopies. The polymer lost only 3% of weight up to 100 °C. The narrowest molecular weight distribution is observed with the fraction between 3,000 and 10,000 Da. P(DAPA) presents a high affinity for the metal ions Pb²⁺ and Cu²⁺, while the other metal ions are not significantly retained. By increasing the filtration factor, Z, metal ion affinity decreases, indicating a very weak ligand-metal interaction and the possibility of its destruction when washed with water at the filtration cell's pH. For Z = 10, the retention values of Pb²⁺ and Cu²⁺ at pH 5 are 76.5% and 48.5%, respectively, while the values for Cu²⁺ and Cd²⁺ at pH 7 are 89.5% and 40.4%, respectively.     

Sorption of a complex of europium (III) with acetylacetone on hydrophobized hexadecyl silica gel and hyper crosslinked polysterene

The sorption of a complex of europium (III) with acetylacetone on silica gel chemically modified with hexadecyl groups (SiO₂-C₁₆) and hyper crosslinked polystyrene (HLPS) was studied. Maximum extraction was observed at pH 5–7 when SiO₂-C₁₆ was used as the sorbent and at pH 4–7 in the case of crosslinked polystyrene. The partition coefficients for HLPS and silica gel were calculated as 7 × 10³ and 1 × 10² cm³/g, respectively. Quantitative extraction of the europium (III) complex was possible in dynamic conditions using a microcolumn (length, 10 mm; internal diameter, 3mm) packed with HLPS at pH 5 (10–50 mL sample volume). Desorption of europium using solutions of nitric acid at different concentrations was investigated. Quantitative desorption was achieved using 5 mL of 1 M HNO₃. A linear range of detection was observed at an amount of europium from 5 to 25 μg in a 10-mL sample (650 nm).     

All‐Polystyrene 3D‐Printed Electrochemical Device with Embedded Carbon Nanofiber‐Graphite‐Polystyrene Composite Conductor

Carbon nanofibres (CNFs) and graphite flake microparticles were added to thermoplastic polystyrene polymer with the aim of making new conductive blends suitable for 3D‐printing. Various polymer/carbon blends were evaluated for suitability as printable, electroactive material. An electrically conducting polystyrene composite was developed and used with commercially available polystyrene (HIPS) to manufacture electrodes suitable for electrochemical experiments. Electrodes were produced and evaluated for cyclic voltammetry of aqueous 1,1’‐ferrocenedimethanol and differential pulse voltammetry detection of aqueous Pb²⁺ via anodic stripping. A polystyrene/CNF/graphite (80/10/10 wt%) composite provides good conductivity and a stable electrochemical interface with well‐defined active geometric surface area. The printed electrodes form a stable interface to the polystyrene shell, give good signal to background voltammetric responses, and are reusable after polishing.     

Studies on some radical transfer reactions by entrapping the radicals as polymer end groups. II. Reactions of ȮH radicals with amino acids

The reaction of ?H radicals with a number of aliphatic amino acids has been studied by entrapping the resultant radicals as end groups of poly(methyl methacrylate) that have been detected and estimated by the sensitive dye partition technique. The rate constants of the reaction (in mol^?1 L S^?1) of 7 amino acids at 25°C and at pH 1.00 have been determined as 8.33 × 10⁸ for glycine, 2.56 × 10⁹ for β-alanine, 2.01 × 10⁹ for β-alanine, 3.99 × 10⁹ for 4-amino butyric acid, 7.56 × 10⁹ for (1+) valine, 1.42 × 10¹⁰ for (1?) leucine, and 5.98 × 10¹⁰ for 6-amino caproic acid. Glycine, α-alanine, β-alanine, and 4-amino butyric acid produced radicals that underwent deamination and incorporated only carboxyl-bearing end groups in the polymer. The other amino acids, leucine, valine, and 6-amino caproic acid, produced at least two types of radicals, radicals that underwent deamination and those that remained intact, and incorporated in the polymer both carboxyl- and amine-bearing end groups but in different amounts. The latter type of radicals were about 29% from 6-amino caproic acid, 23% from leucine, and 18% from valine. The change of pH from 0.80 to 2.72 did not produce any significant change in the end group profile of the polymer obtained, indicating no appreciable change in the rate of the reaction of ?H radicals with the simplest amino acid glycine in the pH range studied.     

Acoustic absorption and dynamic compressibility studies of dilute and concentrated solutions of polystyrene in toluene and cyclohexane

Acoustic absorption and adiabatic compressibility measurements are reported on solutions of polystyrene (M_n = 89,000) in toluene and cyclohexane. The data in toluene cover a temperature range from 293 to 343°K and a concentration range of 10–400 Kg m^?3 (1–40 wt%). The dependence of acoustic absorption on concentration was found to be linear up to 100 kg m^?3, which corresponds to the concentration at which polymer–polymer interactions cause significant changes in the specific viscosity-concentration relationship. Up to 200 kg m^?3 the data could be fitted to computations based on an artificial separation of the dispersion into contributions from viscoelastic and segmental processes, using parameters obtained from a study of narrow molecular weight distribution samples at 25 kg m^?3. However, neither approach was capable of describing dispersions in the 300, 400 kg m^?3 solutions. The modification of the relaxation spectrum observed at the highest concentrations is ascribed to volume and entropy changes associated with alterations of the local environment around a segment of the polymer chain. These changes have their origin in interchain penetration and polymer–polymer contacts, and indicate that ‘entanglement’ is primarily entropic in effect. The adiabatic compressibility exhibited similar deviations from a simple concentration dependence, and allowed estimation of an incompressible volume increment associated with polymer–polymer interactions in the high-concentration entangled matrix. However, the adiabatic compressibilities of solutions of polystyrene, 10–15 kg m^?3, in cyclohexane showed no deviations from simple behavior in the region of the theta temperature. Measurements of the adiabatic compressibility of polystyrene in mixtures of cyclohexane-toluene have been used to obtain the relative magnitude of solvent and polymer contributions to the excess compressibility.     

Synthesis of dihydroxamic acid chelating polymers and the adsorptive property for uranium in sea water

Preparation of new chelating polymers bearing dihydroxamic acid groups and the adsorptive ability for uranium in sea water are described. Chloromethylated polystyrene crosslinked with divinylbenzene was treated with diethyl malonate in N, N-dimethylformamide to give the polymer having diethyl malonate groups. This polymer was then treated with hydroxylamine in methanol to afford the dihydroxamic acid polymer. The presence of hydroxamic acid groups was confirmed by the appearance of IR absorption band at 1680 cm^?1. The dihydroxamic acid polymer contained carboxylic acid groups as well as hydroxamic acid ones, and the contents of carboxylic acid and hydroxamic acid groups were estimated from elemental analysis to be 2–3 and 2–4 mmol/g, respectively. The polymer showed the adsorptive ability of 40 μg-U/g in 8 days for uranium in sea water. In addition, the polymer showed the selective adsorptivity for iron, nickel, copper, and zinc as well as uranium. The macroreticular-type polymer showed much higher adsorption rate for uranium in sea water than the gel-type ones did, suggesting that the rate depends on the diffusion of the uranium in the polymer support.     

COMPARISON OF GPC AND THERMAL FIELDFLOW FRACTIONATION METHODS FOR LINEAR AND STAR BRANCHED POLYSTYRENE SAMPLES

The Thermal Field-Flow Fractionation (TFFF) method was used to determine the elution volumeof a series of star branched polystyrene having different number of arms but the same arm molecularweigh and polystyrene standards with narrow distribution whose molecular weight ranged from5.0×10~4 to 8.6×10~5. Results were obtained by measuring at two temperature difference (△T=30℃and △T=50℃in THF. The same star branched samples were measured by means of GPC method.Comparison of Vr-Mrelationships obtained from TFFF and GPC showed that the displacement of V_r-M curves for star and linear polystyrene is larger than that in GPC. This difference is caused by theentirely different mechanism of separation for these two methods. As the controlling factor is hy-drodynamic volume of the polymer chain in solution for GPC, it is the diffusion coefficient of polymermolecules for TFFF. The experimental results indicate that the influence of variance of chain struc-ture on diffusion coefficient is stronger than that on the hydrodynamic volume and that TFFF tech-nique may be used as a method for characterizing branching of polymer molecules. For this pur-pose a proper theoretical model and more accurate experiments are needed.     

Synthesis and characterization of novel nano size electroactive poly 4,4′‐diaminodiphenyl sulphone

The modification of electrodeposited polyaniline film by subsequent electrodeposition of 4,4′‐diaminodiphenyl sulfone (DDS) leads to a new material having nanostructure. The coated polymer films were treated with various pH solutions. The film adherent characteristics and surface morphology were studied using SEM. The electrochemically synthesized polyDDS revealed good redox behavior. The DDS was also polymerized by the chemical oxidation method using potassium persulphate. The polymer was characterized by UV‐Vis and FTIR spectral studies. The formation of polymer through the N? H group was understood from the single N? H stretching vibrational frequency at 3459 cm^?1. The X‐ray diffraction studies revealed the formation of nano sized (28 nm) crystalline polymer. The conductivity of the polymer was determined to be 1.07 × 10^?4 S.cm^?1. The solubility of the chemically polymerized powder was ascertained, and polyDDS showed good solubility in DMF and DMSO. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1702–1707, 2005     

Tapered copolymers of styrene and 4-vinylbenzocyclobutene via carbanionic polymerization for crosslinkable polymer films

Well-defined polystyrene homopolymers with surface-adhesive triethoxysilyl end group were synthesized via living carbanionic polymerization, epoxide end-functionalization and subsequent hydrosilylation with triethoxysilane. Grafting-to performance of polymers with various molecular weight (M_n = 3000–14,000 g mol⁻¹) to a silicon surface was examined in dependence of reaction time, polymer concentration, solvent and number of alkoxysilyl end groups. Crosslinkable polymers for surface modification were synthesized by statistical carbanionic copolymerization of 4-vinylbenzocyclobutene (4-VBCB) and styrene, followed by epoxide end-functionalization and triethoxysilane modification (M_n = 4000–14,000 g mol⁻¹). The copolymers were characterized by ¹H-NMR, THF-SEC, and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. In situ ¹H-NMR kinetic studies in cyclohexane-d₁₂ provided information regarding the monomer gradient in the polymer chains, with styrene being the more reactive monomer (r_s = 2.75, r_4-VBCB = 0.23). Thin polymer films on silicon wafers were prepared by grafting-to surface modification under conditions derived for the polystyrene homopolymer. The traceless, thermally induced crosslinking reaction of the benzocyclobutene units was studied by DSC in bulk as well as in 3–6 nm thick polymer films. Crosslinked films were analyzed by atomic force microscopy, ellipsometry, and nanoindentation, showing smooth polymer films with an increased modulus. © 2019 The Authors. Journal of Polymer Science published by Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 181–192     

Studies on some radical transfer reactions by entrapping the radicals as polymer end groups. I. Reaction of hydroxyl radicals with amines

The reaction of OH radicals with a number of amines has been studied by entrapping the resultant radicals as polymer end groups which have been detected and estimated by the sensitive dye partition technique. Expressions have been developed relating the average amounts of end groups per polymer molecule to the rate constant of the radical transfer reaction, the rate constants determined for reaction with n-butyl, n-hexyl, and n-octyl amine being 1.00 × 10¹⁰, 1.31 × 10¹⁰, and 1.46 × 10¹⁰ mol^?1 L s^?1, respectively, at 25°C. The order of reactivity for amines of different classes has been found to be as primary < secondary > tertiary, the rate constants for reaction with n-butyl, dibutyl, and tributyl amine being 1.00 × 10¹⁰, 1.81 × 10¹⁰, and 1.67 × 10¹⁰ mol^?1 L s^?1, respectively, at 25°C. The change in the reactivity of the amine with chain length and amine class has been explained by activation and deactivation of the CH₂ group from which H abstraction by OH radicals occurs, respectively, by the alkyl group and by the protonated amino nitrogen under the acidic condition of the medium. Between pH 1.00 and 2.17, the rate of the reaction with n-butyl amine remains practically unchanged, but from pH 2.20 to 2.72 the rate constant increases with increasing pH, indicating that deprotonation of the positively charged nitrogen starts at about pH 2.20. The method is simple and accurate and can be applied to detect and estimate very reactive radicals.     

Phase equilibrium study of the ternary system composed of two monodisperse polystyrenes and cyclohexane

Mixtures of two “monodisperse” samples of polystyrene (M₁ = 4.53 × 10⁴, M₂ = 10.3 × 10⁴; M_w/M_n < 1.01) in cyclohexane were allowed to separate into two phases at different polymer concentrations and temperatures. The compositions in the two phases were measured by gel permeation chromatography, and used to determine isothermal binodals. From the binodal data the critical temperature and concentration were estimated as functions of the composition of the polymer mixture, and the separation factor σ for each polymer component was calculated. In contrast with typical results in the literature, σ was almost independent of molecular weight of the polymer. It is shown by deriving a general expression for σ that theoretical prediction of σ requires accurate knowledge about the Flory–Huggins interaction parameter as a function of the concentrations of individual polymer components.     

Poly(N‐acetyl‐α‐acrylic acid): Synthesis,Characterization and Chelation Properties through Liquid Phase Polymer‐Based Retention Technique

The synthesis and characterization of the water‐soluble poly(N‐acetyl‐α‐acrylic acid) by radical polymerization were carried out. The polymer was characterized by Fourier Transform Infrared (FT‐IR), ¹H NMR and ¹³C NMR spectroscopies, and thermogravimetric analysis (TGA). The metal ion binding properties for the metals Cu(II), Co(II), Ni(II), Cd(II), Zn(II), Pb(II), Hg(II), Cr(III) in the aqueous phase were studied using the liquid‐phase polymer‐based retention technique. The metal ion interactions with the hydrophilic polymer were determined as a function of pH and of the filtration factor. The polychelatogen showed a high affinity for metal ions and higher selectivity for Cr(III) at pH = 3.     

Addition polymerization of 2-cyano-1, 4-benzenedithiol to 1,4-diethynylbenzene and properties of polymers

A novel addition polymerization of 2-cyano-1,4-benzenedithiol to 1,4-diethynylbenzene was carried out by UV irradiation in toluene at 50°C under nitrogen atmosphere. The polymerization proceeded readily, and a pale-yellowish conjugated polymer contain-ing sulfur atoms and cyano groups (M?_n = 20,400–80,800) was obtained in a 60–80% yield for 120–250 min. The polymer was found to be 1 : 1 alternating structure of anti-Markownikoff's type and was insolu-ble in conventional organic solvents. Since the polymer having molecular weight of the order of 10⁴ had a softening point at 115°C, a thin polymer film was obtained by heat press. TG analysis of the polymer indicated its decomposition point at about 620°C under argon atmosphere. The electrical conductivity of the polymer pellet was 10^?10 S/cm at 300 K without doping and on the order of 10^?5 S/cm on I₂ doping. Fur-thermore, the electrical conductivity of the undoped polymer pellet reversibly changed from the order of 10^?10 S/cm at 300 K to 10^?7 S/cm at 435 K with temperature variation, accompanying with increasing carrier density and mobility. The polymer pellet (M?ⁿ = 80,800) aged at 250°C for 5 min under nitrogen atmosphere exhibited the order of 10^?7 S/cm at 300 K. Thermal treatment of the polymers was thought to cause spreading of conjugated system through molecular rearrangement supported by x-ray diagrams. An absorption edge of diffuse reflectance spectra of the polymer (M?ⁿ = 80,800) was 635 nm and shifted to 880 nm by heat treatment of the polymer. © 1995 John Wiley & Sons, Inc.     

A new chelating resin containing azophenolcarboxylate functionality: synthesis, characterization and application to chromium speciation in wastewater

The synthesis of a new stable chelating resin from the polystyrene divinylbenzene copolymer is reported. The polystyrene is first functionalized with a phenolic group and then allowed to couple with diazotized anthranilic acid through the NN bond. The resulting polymer containing azophenolcarboxylate with an ONO chelating environment has been characterized by elemental analysis, hydrogen ion capacity, and water regain value. Its stability towards thermal and different chemical environments has been evaluated. The sorption capacity of the chelating resin for Cr(III) and Cr(VI) as a function of pH has been studied. The interesting point is that chromium(III) is selectively retained at ca. pH 5.0 and chromium(VI) at ca. pH 2.0. When packed in a column, the new material is able to separate Cr(III) from Cr(VI). Five replicate determinations of 10 μg Cr(III) and 10 μg Cr(VI) present in 100 mL solution gave recoveries of 96.9 ± 2.9% (for Cr(III)) and 96.2 ± 2.1% (for Cr(VI)) at the 95% confidence level. Calibration graph was linear over the concentration range of 0-250 μg L⁻¹ of chromium species with correlation coefficient (R) of 0.99994. The detection limits based on 3σ criterion were determined to be 0.6 μg L⁻¹ for Cr(III) and 0.9 μg L⁻¹ for Cr(VI). The developed method was successfully used for the speciation of chromium in wastewater.     

Chemically modified nylons as supports for enzyme immobilization

An isocyanide derivative of nylon, polyisonitrile-nylon (1,2), was used as a starting material whereby, through a series of modification reactions, different chemically reactive functional groups could be introduced on the polyamide backbone. The chemistry employed allowed for considerable flexibility in the choice of procedures for covalent fixation of proteins, all starting from the same chemically reactive parent polymer, polyisonitrile-nylon. Thus, polyisonitrilenylon could be used directly for the immobilization of enzymes via fourcomponent condensation reactions. The isocyanide functional groups of the parent polymer could be transformed, by treatment with bromine, into the strongly electrophilic dibromoisocyanide (—N=CBr^b2) groups. The selectivity of the —N=CBr^b2 group toward the various functional groups present in proteins could be regulated by appropriate control of the pH of the coupling reaction. Dibromoisocyanide-nylon was also further modified into other types of chemically reactive nylon derivatives.     

Carboxylic‐functionalized water soluble π‐conjugated polymer: Highly selective and efficient chemosensor for mercury(II) ions

Here, we report a new carboxylic‐functionalized water soluble π‐conjugated polymer for selective detection of highly toxic Hg²⁺ in neutral pH condition. carboxylic‐functionalized thiophene containing oligophenylenevinylene was synthesized and polymerized under oxidative route to obtain water soluble polymer. Free carboxylic groups present in the π‐conjugated materials provide opportunity to use pH as external stimuli for studying secondary interaction such as hydrogen bonding and aromatic π‐stacking of the chromophores. The pH changes strongly influence on the molecular interactions in the monomer, whereas the long chain polymer was less disturbed. The polymer showed high selectivity for detecting Hg²⁺ ions compared with any other transition metal ions in water. The detection efficiency of the polymer was found almost 40 times higher than that of its monomeric unit. Stern‐Volmer constant for the Hg²⁺ ion sensing was determined through concentration dependent studies as 6.4 × 10⁵ M^?1. The carboxylic‐functionalized polymer showed reversibility in the metal‐ion detecting capabilities which was further investigated by NaCl complexation with Hg²⁺ complex. Both funneling of excitation energy to the Hg²⁺ center and also excitation energy migration through chain π‐conjugated backbone were correlated to the superior sensing characteristics of the polymer compared to its monomeric counterpart. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5144–5157, 2009     

Improve the physical and chemical properties of biocompatible polymer material by MeV He ion beam

There is a high interest in improving the hydrophilicity of polymer surfaces due to their wide use for technological purposes. In this study Ultra High Molecular Weight Polyethylene (UHMWPE) as a biocompatible material was bombarded with 1 MeV He ions to the fluences ranging from 1×10¹³ to 5×10¹⁴ cm^?2. The pristine and ion beam modified samples were investigated by photoluminescence (PL), ultraviolet–visible (UV–vis) spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The changes of wettability and surface free energy were determined by the contact angle measurements. The obtained results showed that the ion bombardment induced decrease in integrated luminescence intensity and decrease in the transmittance with increase of ion fluence as well. This is might be attributed to degradation of polymer surface and/or creation of new electronic levels in the forbidden gap. The FTIR spectral studies indicate that the ion beam induces chemical modifications within the bombarded UHMWPE. Formation of carbonyl groups (C=O) on the polymer surface was studied. Direct relationship of the wettability and surface free energy of the bombarded polymer with the ion fluences was observed.