马来酸酐聚合反应动力学的回归模拟

本文从函数变量相关内函规律出发，引用动力学物理概念，用数值逼近方法，对马来酸酐聚合反应的实验结果进行了模拟，得到了一符合实验规律的动力学方程。     

Preparation of copolymer of acetylene and butadiene

Conditions for preparation of acetylene–butadiene random copolymers were investigated. Only a combination of organonickel compound and dialkylaluminum halide was able to copolymerize acetylene and butadiene to give soluble, linear, random copolymers in high yield. Toluene and xylene were the preferred solvents for the copolymerization. The catalyst activity and copolymer composition were influenced by the Al/Ni molar ratio, polymerization temperature, polymerization time, and conditions of preparation of catalyst.     

Hydrolysis study of organic acid anhydrides by differential thermal analysis--II. Maleic anhydride and trimellitic anhydride

Differential thermal analysis has been used to follow the hydrolysis of maleic anhydride (MA) and trimellitic anhydride (TMA). On exposure of MA to an atmosphere of 96 % relative humidity, maleic acid is produced, hydrolysis being complete in 21 hr at 22 degrees, but no hydrolysis occurs at a relative humidity of 50%. When exposed to an atmosphere of 96% relative humidity, TMA is quite stable for short periods, but hydrolyses slowly, the production of trimellitic acid being complete in 113 hr at 22 degrees.     

New catalytic systems for oxidative carbonylation of acetylene to maleic anhydride

A classification of polyfunctional catalytic systems based on discrimination of the main component (the catalyst participating in all stages of the formation of the product of catalytic reaction) and elucidating the functions of additional components of a catalytic system is suggested. The role of additional components in a number of new palladium-based catalytic systems used in the synthesis of maleic anhydride by oxidative carbonylation of acetylene was studied. It was established that the functions of Co and Fe phthalocyanine complexes (PcCo and Pc^*Fe, respectively) in the mechanism of the process are different. Translated fromIzvestia Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1899–1905, October, 1999.     

Maleic anhydride as a reagent for the determination of hydroxyl groups in organic compounds

The reaction of esterification by maleic anhydride in methyl ethyl ketone in the presence of triethylamine is proposed for the determination of alcohol hydroxyl groups. The equivalent amount of maleic anhydride that entered into the reaction is determined spectrophotometrically by the reaction with 2-methylimidazole. In the determination of hydroxyl groups in epoxy-dian resins, maleic anhydride is determined by the potentiometric titration with alkali after hydrolysis with water by the first potential jump.     

Studies of photochemical transformations in polystyrene and styrene-maleic anhydride copolymer

Thin films of polystyrene (PS) and styrene-maleic anhydride copolymer (St-MAn) were exposed to monochromatic UV radiation (254 nm) for varied time intervals. The course of photochemical transformations was monitored by absorption spectroscopy (FT-IR, UV-vis) and thermogravimetry, which were also applied for the estimation of the thermal stability of samples studied. The changes of surface properties were monitored by contact angle measurements.Changes in chemical structure were found in irradiated films (inside and at the surface). The efficiency of photooxidative degradation in St-MAn copolymer was slightly lower than that in PS homopolymer but photo-crosslinking and chromophore formation were enhanced. An increase of hydrophilicity and oxidation degree in UV-irradiated samples was accompanied by destruction processes. The thermal stability of St-MAn was lower in comparison to polystyrene alone.The mechanism of photochemical reactions in the copolymer is proposed.     

Maleic anhydride and chromone derivatives from the endophytic fungus BCC 54265 (Botryosphaeriaceae)

A maleic anhydride derivative, botryoanhydride (1), and a chromone derivative, botryochromone (2), together with three known chromones, eugenitin (3), 6-hydroxymethyleugenin (4) and 6-methoxymethyleugenin (5), were isolated from cultures of the endophytic fungus BCC 54265 of the family Botryosphaeriaceae. The structures were elucidated on the basis of NMR, HRMS and CD data. Compound 2 showed weak cytotoxic activity to cancer cell-lines.     

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.     

Model potential energy surfaces for approach of an electrophile to acetylene and fluoroacetylene

Non-empirical LCAO MO SCF calculations have been made on cross sections through prototype potential energy surfaces for the initial approach of an electrophile to acetylene and fluoroacetylene. The electrophile has been simulated by a unit positive charge and this is shown to give a computationally inexpensive means of providing information on such processes.     

Diblock copolymer lamellae on sinusoidal and fractal surfaces

A scaling analysis of equilibrium orientation of diblock copolymer molecules on fractal surfaces and a brief comparison with a particular experiment is presented in this paper. This work is motivated by a recent experimental finding that a diblock copolymer film of polystyrene-PMMA, when deposited on a rough substrate, can orient its lamellae from a parallel to a perpendicular configuration depending on the topographical characteristics of the substrate surface. It was found that the RMS height itself is not enough to effect the equilibrium configuration, but the fractal dimension of the surface is also important. In general, the orientation of lamellae is a function of the the power spectral density (PSD) curves of the underlying substrate surface. Assuming the diblock lamellae to behave like an Alexander-deGennes brush, we obtain the free energy expressions for this brush in both parallel and perpendicular orientations in various asymptotic regimes. Comparison of their free energy expressions predicts the equilibrium configuration. By examining the PSD curves and using our scaling results, we are able to qualitatively explain some aspects of the experimental observations regarding the equilibrium orientation of the diblock copolymer lamellae on rough surfaces.     

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.     

Maleic anhydride incorporated onto cellulose and thermodynamics of cation-exchange process at the solid/liquid interface

This investigation explores the chemical modification of cellulose by using a quasi solvent-free procedure, in which the biopolymer was added to molten maleic anhydride, producing a mixture of maleated and fumarated celluloses. Using this pathway mainly surface modifications are observed and more than 2.82 ± 0.05 mmol of modifier per gram of synthesized polymer were obtained. These chemically modified materials were characterized by elemental analysis, solid-state ¹³C NMR CP/MAS, FTIR, XRD, TG and SEM. The chemically modified polysaccharides are able to adsorb cations. The data were adjusted to a modified Langmuir equation to give 1.75 ± 0.09 and 2.40 ± 0.12 mmol/g of Co²⁺ and Ni²⁺, respectively. The net thermal effects obtained from calorimetric titration measurements were also adjusted to a modified Langmuir equation and the enthalpy of the interaction was calculated to give the endothermic values of 0.29 ± 0.02 and 0.87 ± 0.02 kJ/mol for Co²⁺ and Ni²⁺, respectively. The thermodynamic data for these systems are favorable for cation adsorption from aqueous solutions at the solid/liquid interface, suggesting the use of this anchored biopolymer for cation removal from the environment.     

Analysis of copolymer surfaces by surface reactions and XPS

Summary The adsorption of polar groups at the polymer melt/mould interface is detected by chemical analysis. Vinyl alcohol groups and vinyl acetate groups (after hydrolysis) react with heptafluoro-butanoic acid chloride to attach a fluorine-containing molecular group to the surface. By measuring fluorine and other elements with XPS the surface composition is determined. On a gold substrate vinyl alcohol groups are adsorbed in a copolymer of vinyl chloride, vinyl acetate and vinyl alcohol. If a vinyl chloride-vinyl acetate copolymer is compression moulded against gold, the polymer surface energy is increased by adsorption of vinyl acetate groups. Subsequent relaxation, after removal of the substrate, leads to slow desorption of vinyl acetate groups. At the interface of the vinyl chloride-vinyl acetate copolymer with nickel or aluminium the polymer is oxidized.

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Zusammenfassung Die Adsorption von polaren Gruppen an der Polymerschmelze/Substrat — Grenzfläche wird chemisch analysiert. Vinylalkohol- und Vinylazetatgruppen in Oberflächen von Copolymeren reagieren (nach Hydrolyse) mit Heptafluorbuttersäurechlorid. Mit XPS (X-ray-Photoelectron-Spectroscopy) messen wir die Fluormenge, um die Oberflächenzusammensetzung zu bestimmen. In PVC/Ac/Alc Copolymerem adsorbieren Vinylalkoholgruppen an ein Goldsubstrat. Die Zunahme der Oberflächenenergie von PVC/Ac durch Schmelzen auf einer Goldoberfläche und die spätere Relaxation, werden verursacht durch Adsorption und Desorption von Vinylazetateinheiten. Bei Gebrauch von Nickel oder Aluminium wird die Polymeroberfläche oxydiert.

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With 3 tables     

Reactor design and energy concepts for a plasma process of acetylene black production

Acetylene black can be produced from methane decomposition in a plasma reactor. Different types of plasma reactor are designed for this purpose and a parametric analysis of the system is made. Carbon yield in the reactor seems to be dependent on methane flow rate and plasma power. The results obtained from various types of material analysis of the product obtained show that in some conditions carbon produced under plasma has qualities similar to acetylene black obtained by classical processes.     

Side-chain-grafted random copolymer brushes as neutral surfaces for controlling the orientation of block copolymer microdomains in thin films

Random copolymers of P(S-r-MMA-r-HEMA)s with a distribution of surface reactive hydroxyl groups were synthesized to formulate neutral surface layers on a SiO2 substrate. The layers were designed to drive vertical orientation of lamellar microdomains in a top P(S-b-MMA) thin film. Copolymers with a styrene weight fraction (f(St)) of 0.58 and a HEMA fraction (f(HEMA)) ranging from 0.01 to 0.03, with a corresponding MMA fraction (f(MMA)) ranging from 0.41 to 0.39, in the P(S-r-MMA-r-HEMA) copolymer showed neutral surface characteristics. The morphology of block copolymer thin films was studied by scanning electron microscopy (SEM). P(S-r-MMA-r-HEMA) copolymers prepared by both living and classical free-radical polymerizations were equally effective in demonstrating the neutrality of the surface. These side-chain-grafted random copolymer brushes showed faster grafting kinetics than the end-chain-grafted P(S-r-MMA) because of multipoint attachment to the surface. The modified surfaces had a very thin layer of random copolymer brush (5-7 nm), which is desirable for effective pattern transfer. Furthermore, neutral surfaces could be obtained even when the grafting time was reduced to 3 h. These results indicate that the composition of the random copolymer brush, rather than its PDI or molecular weights, is the most important factor in controlling the neutrality of the surface. These results also demonstrate the feasibility of using a third comonomer (C) in the random copolymer brush P(A-r-B-r-C) to alter the interfacial and surface energies of a diblock copolymer (A-b-B).     

Cationic ester-containing gemini surfactants: adsorption at tailor-made surfaces monitored by SPR and QCM

Adsorption of a series of ester-containing cationic surfactants at a surface containing 90% methyl groups and 10% carboxyl groups was studied by two surface analysis techniques, surface plasmon resonance (SPR) and quartz crystal microbalance (QCM). Such a surface, which is at the same time hydrophobic and negatively charged, is of interest as a model for many polymeric surfaces. Two different types of ester gemini surfactants and their monomeric counterparts were included together with nonester containing surfactants of similar structure. The results show that the gemini surfactants give the same adsorbed amount at the surface as the monomeric surfactants when compared at the same bulk concentration normalized to the critical micelle concentration (cmc) in bulk. Since the cmc of the geminis is around 20 times lower than the cmc of the corresponding monomeric surfactants, the gemini surfactants are much more effective in covering the surface. The two techniques gave similar relative values but the QCM values were always higher than those from SPR, which is due to the former method taking also adsorbed water into account. The adsorption, as measured by both methods, was found to follow closely the Langmuir adsorption model.     

Wettability of tri-block copolymer coated hydrophobic surfaces Predictions and measurements

Hydrophobic surfaces with adsorbed tri-block copolymers are wetted by oil in spite of the hydrophilic buoy groups of the block copolymer that are present near the surface. The effect of the buoy group length of the adsorbed molecules on the wettability of hydrophobic surfaces is studied by contact angle measurements and by computer modelling.

The computer model predicts an increase in interfacial free energy with increasing buoy group length for equilibrium adsorption of block copolymer from water. Molecules with large buoy groups occupy more lateral space; therefore the “bare” surface gets more exposed and the anchor groups contribute less to the interfacial free energy which thus increases with the buoy group length.

The calculations showed that the variation of the interaction parameter between solvent and buoy group hardly influences the interfacial free energy. In contrast the interaction parameter between solvent and surface influences the interfacial free energy to a large extent because the oil/surface interactions have a lower energetic value as compared to water/surface interactions and therefore the interfacial free energy is lower than in water. The interfacial free energy varies slightly with increasing buoy group length, depending on the value chosen for the solvent/surface interaction parameter.

Advancing and receding contact angles of hexadecane, sunflower oil and hydrolysate (partly hydrolysed sunflower oil) were measured on hydrophobic surfaces. All oil/water contact angles were small, indicating a hydrophobic apolar surface character. It was found that, for oils with a “good” interaction with the surface (hexadecane and sunflower oil), the contact angle has a minimum value at a certain buoy group length. For hydrolysate (less-strong interaction with the surface) the contact angle decreases monotonically with increasing buoy group length. The results for hexadecane, sunflower oil and hydrolysate are in reasonable agreement with the model predictions. The effect of increasing buoy group length is weak; both decreasing and increasing angles are found, depending on the type of oil used.     

Rapid polymer brush growth by TEMPO-mediated controlled free-radical polymerization from swollen plasma deposited poly(maleic anhydride) initiator surfaces

Pulsed plasma-chemical deposition of poly(maleic anhydride) is shown to be a substrate-independent method for functionalizing solid surfaces with initiator sites for nitroxide-mediated controlled free-radical graft polymerization. Swelling of the initiator film via aminolysis can lead to grafted polymer brushes that are 1 order of magnitude thicker than those obtained by existing methods on solid surfaces.