热重法测定高马来酸酐含量苯乙烯-马来酸酐共聚物的组成

高马来酸酐含量苯乙烯-马来酸酐共聚物(SMA)是一种具有优良耐热性、刚性和尺寸稳定性的新型高分子材料.由于SMA分子中含有极性很强、反应活性很高的酸酐官能团,所以它被广泛应用于涂料、粘合剂的改性剂、地板抛光的乳化剂、复合材料和颜料的分散剂、水处理剂等领域[1-5].     

Amine-modified maleic anhydride containing terpolymers for the adsorption of uranyl ion in aqueous solutions

Maleic anhydride–styrene–methyl methacrylate (MA–S–MM) terpolymer was prepared. It was modified by ethylenediamine (EDA) and diethylenetriamine (DETA) in order to get cross-linked polymers bearing carboxyl and amine groups. Modified polymers used as an adsorbent for the removal of UO₂ ²⁺ from water. The characterizations of structures of all the polymers were performed by Fourier transform infrared. The adsorptive features of adsorbents were then investigated for UO₂ ²⁺ in view of dependency on ion concentration, pH, temperature and kinetics. Experimentally obtained isotherms were evaluated with reference to Langmuir, Freundlich and Dubinin–Radushkevich models. The maximum monolayer adsorption capacity for UO₂ ²⁺ was found to be 1.59 and 2.43 mol kg^?1 for EDA–MA–S–MM and DETA–MA–S–MM, respectively. It can be said that the new modified polymers prepared in our laboratory have been suggested as new adsorbents for uranyl ions.     

Structure study of the furan–maleic anhydride copolymer

A structural study of furan–maleic anhydride copolymer (F–MAH) was undertaken to confirm its alternating nature and to determine its microstructure. The spectral properties of a model compound representing the alternating repeat unit, 2-(2-tetrahydrofuranyl)succinic anhydride, were compared with those of F–MAH. Their infrared (IR), ¹H, and ¹³C nuclear magnetic resonance (NMR) spectra (after compensating for the absence of the olefinic double bond) were in good agreement with those of the copolymer. Furthermore, the observed splitting in the ¹H- and ¹³C-NMR spectra of F–MAH were assigned to cis–trans linkages on both the F and MAH units, with cis linkage being favored on both units, especially the former. The structure of 2,5-dimethylfuran (DMeF)–MAH copolymer is similar to that of F–MAH copolymer, except that the preference of cis linkages is less pronounced. The structure of 2-methylfuran (MF)–MAH copolymer is a complex structure with numerous 2,3-furandiyl units. A mechanistic study was undertaken to elucidate the roles of F–MAH Diels–Alder adduct, and the charge-transfer (CT) complex in the radical initiated copolymerization. The adduct reverted substantially to monomers under the reaction conditions; but, the amount of adduct remaining at equilibrium was quite appreciable; therefore, its participation could be ruled out on this basis alone. However, on polymerizing the adduct in the presence of F-d₄, the latter was incorporated into the copolymer to an extent indicative of free monomer exchange. Therefore, the adduct cannot be directly involved in the polymerization.     

Behavior of thermo- and pH-responsive copolymer of N-isopropylacrylamide and maleic acid in aqueous solutions

A thermo- and pH-responsive copolymer of N-isopropylacrylamide with maleic acid was studied using light scattering and turbidimetry methods. Aqueous solutions with pH values from 1.8 to 10.9 and in the concentration range from 0.001 to 0.015 g/cm³ were investigated. At all pH values and concentrations, phase separation was observed at temperatures T > 33°C. The temperatures of the start and the width of the phase separation interval increased with decrease of copolymer concentration and increase in pH. The redistribution of scattering entities, namely, macromolecular unimers, micelle-like structures, and loose aggregates, and growth of aggregate hydrodynamic radius took place during heating.     

Protonation equilibria of rauwolfia alkaloids in sulfuric acid solutions

The pK_a values for the indole ring protonation equilibria of the Rauwolfia alkaloids, yohimbine, ajmalicine, reserpine and reserpiline have been measured in strongly sulfuric acid solutions. The alkaloids obey the H_I acidity function stablished by Hinman and Lang for indole ring protonation, but they are considerably weaker bases than alkylindoles. Evidences indicating that these compounds behave as carbon bases are reported.     

RAFT radical copolymerization of beta‐pinene with maleic anhydride and aggregation behaviors of their copolymer in aqueous solution

RAFT copolymerization of beta‐pinene and maleic anhydride was successfully achieved for the first time, using 1‐phenylethyl dithiobenzoate as chain transfer agent in a mixed solvent of tetrehydrofuran and 1.4‐dioxane (1:9, v/v) at a feed molar ratio of beta‐pinene to maleic anhydride as 3:7, and the alternating copolymer was prepared with predetermined molecular weight and narrow molecular weight distribution. Furthermore, using former alternating copolymer as a macro‐RAFT agent, block copolymer poly(beta‐pinene‐alt‐maleic anhydride)‐b‐polystyrene was synthesized in a chain extending with styrene. Hydrolysis of this block copolymer under acidic conditions formed a new amphiphilic block copolymers poly(beta‐pinene‐alt‐maleic acid)‐b‐polystyrene whose self‐assembly behaviors in aqueous solution at different pH were investigated through SEM and DLS. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1422–1429     

Pulsed plasma polymerized maleic anhydride films in humid air and in aqueous solutions studied with optical waveguide spectroscopy

Optical waveguide spectroscopy (OWS) was employed to monitor the swelling behavior of pulsed plasma polymerized maleic anhydride (PPPMA) films in humid air and in aqueous solutions by measuring the film thicknesses and refractive indices. With the relative humidity of air increasing, both the thickness and the refractive index of the PPPMA films increased, indicating water penetration into and uptake by the films. The swelling of the hydrated PPPMA films in humid air is reversible. In aqueous media, the thickness and the refractive index of the washed PPPMA film increased with an increase of pH and ionic strength, respectively. On the basis of the present data, a hypothesis concerning the structure of the PPPMA film is proposed. Our model suggests that the unique structure of the PPPMA films originates from the cyclic structure of maleic anhydride and depends on parameters of the plasma deposition process, and the interaction between H(2)O and the carboxylic groups.     

Preliminary study of extractable protein binding using maleic anhydride copolymer

A preliminary study of using maleic anhydride copolymer for protein binding has been carried out.The polymeric films were prepared by compression of the purified resin and annealing the film to induce efficient back formation of the anhydride groups.The properties of the film surface were analyzed by attenuated total reflection Fourier transforms infrared spectroscopy and water contact angle measurements.The protein content was determined by Bradford assay.To obtain optimum conditions,immersion time for protein binding was examined.Results revealed that proteins can be successfully immobilized onto the film surface via covalent linkage.The efficiency of the covalent binding of the extractable protein to maleic anhydride-polyethylene film was estimated at 69.87μg/cm~2,although the film had low anhydride content(3%) on the surface.     

Stereochemistry of alternating methacryloyl-L-valine methyl ester–maleic anhydride copolymer

The stereochemical composition of an alternating methacryloyl-L -valine methyl estermaleic anhydride (L-MAVM/MAn) copolymer which was prepared by the photocopolymerization of L-MAVM and MAn in dioxane at 25°C without initiator was investigated by proton magnetic resonance spectroscopy. The resonance of the ester methyl protons of the L-MAVM unit appeared as three split peaks at 3.65, 3.76, and 3.82 ppm, which could be assigned to those of the coisotactic (di-threo-tri-isotactic), coheterotactic and cosyndiotactic triads, respectively. The triad cotacticity determined according to these assignments indicated that the copolymer was composed predominantly of di-threo-tri-isotactic triad. Similarly PMR spectroscopic investigation of the acryloyl-L -valine methyl ester–maleic anhydride (L-AVM/MAn) copolymer with a 1:1 molar ratio of the monomers showed that the main tactic fraction of the copolymer was also di-threo-tri-isotactic one. Nevertheless, the circular dichroic investigation of the L-AVM/MAn copolymer before and after hydrolysis denied asymmetric induction into the polymer main chain. These results suggest that the propagation step in the photocopolymerization of L-MAVM or L-AVM with MAn proceeds by the trans-trans opening of the complexmer composed of a 1:1 molar ratio of L-MAVM or L-AVM and MAn.     

Chemical initiation mechanism of maleic anhydride grafted onto styrene-butadiene-styrene block copolymer

The mechanism of grafting styrene-butadiene-styrene (SBS) tri-block copolymer with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2^′-azo-bis-isobutyronitrile (AIBN) was studied by FTIR and ¹H NMR spectroscopies. The variation of CC (double bond) content in SBS-g-MAH was used to verify the different graft mechanisms of BPO and AIBN, indicating that the chemical initiation mechanisms of MAH grafted onto SBS of AIBN is different from that of BPO. The graft reaction occurs by addition on CC for AIBN, while by removal of an allylic hydrogen atom from SBS and by addition on CC at the same time for BPO. The graft efficiency of AIBN is higher than that of BPO in this system.     

Surface modification of fine colloidal silica with copolymer silane-coupling agents composed of maleic anhydride

The reactivity of copolymer silane composed of maleic anhydride in the modification of fine colloidal silica was studied. The reaction of colloidal silica of 10 and 45-nm diameter with trimethoxysilyl-terminated poly(maleic anhydride-co-styrene) [P(MA-ST)] and poly(MA-co-methyl methacrylate) in tetrahydrofuran resulted in effective surface modification without particle aggregation. From the results that the reaction using the polystyrene silane of low molecular weight led to partial aggregation, it was suggested that the steric interaction between relatively rigid copolymer chains having a maleic anhydride moiety adsorbed on the silica prevented the aggregation in the reaction. The ²⁹Si cross-polarization magic-angle-spinning NMR spectra of P(MA-ST)-modified silica showed that the polymer silane was bound to the silica surface by the direct reaction with silica hydroxyl groups and via the polymerization. Received: 27 June 2001 Accepted: 6 September 2001     

Alternating polyampholytes prepared by hydrolysis of copolymer of maleic anhydride and N-vinylsuccinimide

Alternating polyampholytes (MA-VA) containing two acidic groups and one basic group were prepared by the copolymerization of maleic anhydride (M₁) and N-vinylsuccinimide (M₂) at 60°C with AIBN as the initiator, followed by acid hydrolysis with 1N hydrochloric acid at 140°C for 24 hr. The monomer reactivity ratios r₁ and r₂ are 0.025 and 0.06, respectively. The structure of polymers was discussed on the basis of the data of their elementary, infrared (IR), and thermal analyses and the binding ability of heavy metal ion. Polyampholytes were soluble in strong acidic and basic media but were precipitated in the pH range 3–4. An isoelectric point at pH 3 was determined by potentiometric titration and the turbidimetric method. By thermal treatment above 205°C the polyampholyte turned quantitatively into a cyclized lactam. This suggests that the polyampholyte MA–VA has an intramolecular hydrogen bond between the amino and γ-carboxyl groups. The binding of Cu²⁺ and Hg²⁺ by the polyelectrolyte was evaluated by equilibrium dialysis.     

Controlled phase separations in solutions of soluble polyelectrolyte complex of DIVEMA (copolymer of divinyl ether and maleic anhydride)

Copolymer of divinyl ether and maleic anhydride (DIVEMA) is known to possess some anti-tumor and immune-stimulating activity and use as a drug carrier in anti-tumor drug delivery systems. Samples of DIVEMA of different degrees of polymerization were synthesized and characterized. Interaction of the hydrolyzed water-soluble DIVEMA polyanions with poly(N-ethyl-4-vinylpyridinium) cations (PEVP) has been studied. According to the potentiometry data, almost all carboxylic groups of the polyanions were able to form ion pairs with PEVP. In aqueous and water-salt solutions, formation of either soluble or insoluble polyelectrolyte complexes occurred depending on pH, ratio of the oppositely charged groups, and degree of polymerization of PEVP and/or DIVEMA. The phase separations followed general rules revealed by studying mixtures of PEVP and polycarboxylic acids. However in the case of DIVEMA, a significant broadening of the region for insoluble complexes at the expense of the region of soluble complexes was established. The data obtained demonstrate plausible advantages of the complex formation as the non-covalent modification of the polymeric carrier that endow DIVEMA with the ability for reversible soluble-insoluble transformation, in particular at physiological pH and ionic strength.     

Protolytic equilibria in aqueous sodium deoxycholate solutions

Protolytic equilibria taking place in aqueous solutions of sodium deoxycholate (DCNa) have been studied at 25°C using 0.5M NaCl as ionic medium. Electromotive force measurements of a galvanic cell were carried out by means of a glass electrode.The reagent necessary to change the acidity of the solutions was produced in situ by supplying a constant small current.Solubility and acid constant of deoxycholic acid (HDC) have been determined for the chosen experimental conditions. Experimental data obtained in less acid solutions have been explained by assuming the presence of the species H(DC)₂. The relative stability constant has been determined. At higher deoxycholate concentration the presence of a polymeric micellar species has been assumed.

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Protolytische Gleichgewichte in wäßrigen Natriumdesoxycholat-Lösungen

Zusammenfassung Die Protonierung von Natrium-Desoxycholat (DCNa) in wäßrigen Lösungen mit 0.5M NaCl wurde bei 25°C mit Hilfe von E.M.K. Messungen mit einer Glaselektrode untersucht.Das notwendige Reagens für die Umwandlung der Säure in den untersuchten Lösungen wurde in situ durch einen konstanten schwachen Strom erzeugt.Löslichkeit und Dissoziationkonstante von Desoxycholsäure (HDC) wurden unter den gewählten experimentellen Bedingungen bestimmt. Die experimentellen Daten in schwach sauren Lösungen konnten mit der Annahme der Existenz von H(DC)₂ erklärt werden. Die entsprechende Konstante wurde bestimmt. Zur Erklärung der Daten in stärker konzentrierten Lösungen von Desoxycholat ist die Annahme einer polynuklearen Spezies nötig.

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Symbols H analytical excess of hydrogenions, if negative it corresponds to OH^–; - h free concentration of hydrogen ions; - A total concentration of deoxycholate; - a free concentration of deoxycholate; - K _a acid constant of deoxycholic acid (HDC) defined as follows: [HDC]K _a =ha; - _q,p stability constant of a speciesH _p (DC) _q defined as follows: [H _p (DC) _q ]= _q,p h ^p a ^q ; - C ⁰ solubility of HDC; - formation function representing the average number of H⁺ bonded to deoxycholate.     

Charge transfer complex formation in in-situ maleic anhydride and N-vinyl caprolactam copolymer and copolymer/organo-montmorillonite nanoarchitectures

The binary copolymerization of maleic anhydride (MA) and N-vinyl caprolactam (VCL) or considered as acceptor (A)?donor (D) monomer systems were used (MA:VCL) 50:50 in BPO (0.5%) as an initiator at 70°C under nitrogen atmosphere. The functional copolymers, having a combination of rigid/flexible linkages and an ability of complex-formation with interlayered surface of organo-silicate, and their nanocomposites have been synthesized. Interlamellar in situ complex-radical copolymerization of intercalated monomer complexes of MA and VCL undergoes with stearyl amine surface modified montmorillonite (O-MMT) and monomer mixtures. Charge transfer complex formation was followed and identified by UV-Vis-NIR spectroscopy. Equilibrium constant (K_AD) molar absorption coefficient (?^AD)) of the complex were determined by the Benesi-Hildebrand, Scott and Ketaalar equations respectively. The results show that copolymerization of MA:VCL system was preceded via alternating copolymerization mechanism. Obtained functional alternating copolymer and copolymer/O-MMT nanostructures were characterized by XRD and TEM.     

Conformational transition of the copolymer of maleic acid and styrene in aqueous solution

The pH-induced conformational transition of maleic acid–styrene copolymer in aqueous NaCl solutions has been investigated by potentiometric titration, viscosimetry, and dilatometry. The dependence of the intrinsic viscosity on the degree of neutralization of the primary carboxyl group indicates that the transition is from a compact to a loosely coiled form. From titration data, the standard free energy change ΔG° per monomole, for the transition from the uncharged compact from to the hypothetical uncharged loosely coiled one is estimated to be about 370–280 cal/monomole for concentrations ranging from 0.0092 to 0.2739N in NaCl. The value of ΔG° decreases slightly with increasing temperature in the temperature range from 15 to 30°C. The volume change associated with the transition was found to be ?0.6 ml in 0.01N NaCl and ?0.9 ml in 0.09N NaCl per monomole, respectively. From viscosity data, changes of molecular dimensions and the long-range interaction parameter through the transition region have been discussed.     

Increase in the content of maleic anhydride units in a copolymer with methyl methacrylate in the presence of 1,3,5-trithiane

The use of 1,3,5-trithiane as agent controlling copolymerization of maleic anhydride with methyl methacrylate allows preparation of the copolymer with increased content of anhydride units because of the radical complex mechanism of the process under these conditions.