Epoxy groups on grafted polypropylene. I. Reaction with acids

Epoxy groups on isotactic polypropylene, to which 2,3-epoxypropylmethacrylate was grafted, were reacted with low molecular carboxylic acids. The reaction proceeds under heterogeneous conditions in the presence of organic solvents and it may be catalysed by tertiary amines. The rate constants of this reaction are correlated with the dissociation constant of the bonded acid and with the character of the used catalyst. The reactivity of polymer-bonded epoxy groups is not changed when comparing with reactions performed under homogeneous conditions.     

Modification of poly(octadecene‐alt‐maleic anhydride) films by reaction with functional amines

Thin films of poly(octadecene‐alt‐maleic anhydride) on top of Si wafers and glass plates were modified by reactions with different functional amines to be used in future studies on the relevance of certain molecular surface properties for the covalent immobilization of proteins. For that aim, a strategy was developed and applied to convert the anhydride moieties of the copolymer by functional amines into side chains bearing hydrophilic groups of acidic (carboxylic acid, sulfonic acid), basic (amines), or neutral (poly(ethylene oxide) (PEO), glucose) character. The modification of the copolymer films was achieved through the two‐step formation of a cyclic imide, which was very stable in aqueous solution. Depending on the reactivity of the applied amine, the adjustment of the reaction time was suitable for the preparation of partially converted surfaces of the polymer film. Degrees of modification between 5 and 30% (according to X‐ray photoelectron spectroscopy data) were obtained. Annealing the modified polymer films induced efficient back‐formation of the anhydride groups. By reaction of the layered polyanhydrides with highly crosslinked diamines, amine‐functionalized polymer films were produced that were capable of binding secondary polyanhydride layers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1255–1266, 2003     

The polyurea structure and the role of Amine-Terminated Polyethers and Polyesters in Polyurethanes

The Reaction Injection Molding (RIM) technology has made it possible to master the fast reaction of di- and polyamines with di- and polyisocyanates, leading to the preferred polyurea structure. Telechelics with amino end groups are gaining increased interest for the manufacture of polyurethane-polyurea materials by this technology. They make it possible to substitute all urethane groups in the elastomers with urea groups. The telechelics which are considered are amine-terminated polyethers (ATPE) and polyesters based on the typical soft-segment forming polycondensation polymers which are widely used in polyurethane chemistry. Isocyanate-terminated prepolymers of toluene diisocyanate and polyether polyols can be hydrolyzed in aqueous alkaline media via the carbamate intermediate to the amineterminated prepolymers. The reactivity of these aromatic ATPEs was ideally fit for the RIM process. ATPEs by the hydrolysis process are somewhat limited if products with low viscosities are required. In the reaction of chloro-nitrobenzenes with polyether polyols followed by the hydrogenation of the nitro groups of the terminal phenoxy moieties, we found a path for the synthesis of low viscosity aromatic ATPEs. Capping of polyether polyols with acetoacetate groups and subsequent reaction of the acetoacetylated polyethers with amines, leads to polyethers with terminal imine or enamine groups, which are derivates of aminocrotonic acid. We determined that this approach is a universal method for the synthesis of a large variety of aromatic as well as aliphatic ATPEs with low viscosities. Trifluoroacetic acid turned out to be the ideal catalyst for the reaction of the acetoacetylated polyethers with aromatic diamines, one amino group forming the imine link, the second one remaining intact and providing the desired reactivity towards isocyanates. Aliphatic diamines do not require a catalyst for this reaction. They lead to aminocrotonates with aliphatic amino groups that have high reactivity towards isocyanates, which is to be expected from aliphatic amines. The reaction of the chloroformates of polyether polyols with diamines can also be used to synthesize a variety of ATPEs. We recently developed an approach to low viscosity ATPEs having secondary amino end groups. The hydroxyl groups of the polyether polyols are converted to chloride or methanesulfonyl. The polyethers terminated with these leaving-groups are reacted with primary aliphatic or aromatic amines to give the secondary ATPEs in very good yields.     

Nachweis von ω-Aminocarbonsäuren und Carbonylverbindungen in thermooxidativ abgebautem Polycaprolactam

After oxidation and subsequent hydrolysis homologous series of alkyl amines and ω-amino carboxylic acids were proved to be further degradation products of polycaprolactam. The formation of these substances cannot be explained by an attack on the N-vicinal methylene group which is the most reactive site of this polymer. Considering the low and nearly equal amount of nitrogen containing degradation products a statistical attack on the remaining methylene groups takes place besides the preferred N-vicinal reaction. The CO-vicinal site is not particularly activated. The formation of likewise isolated substances with carbonyl groups cannot be explained by a uniform mechanism.     

Changes in graphite oxide texture and chemistry upon oxidation and reduction and their effect on adsorption of ammonia

Two graphite oxides were prepared by a subsequent two-step oxidation of commercial graphite. The samples were then reduced with hydrazine hydrate. Surface characterization before and after exposure to ammonia was carried out using X-ray diffraction, Fourier-transform infrared spectroscopy, potentiometric titration, X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, thermal analysis and nitrogen adsorption. The results indicated significant differences in the texture and chemistry of the materials, which had effects on their ammonia adsorption capacity. Strong oxidation led to relatively amorphous samples with a developed porosity owing to the treatment. Acidity is governed by the presence of sulfonic and carboxylic groups. Even though these groups react with ammonia, the significant adsorption capacity is linked to the presence of surface epoxides, which can react with ammonia leading to the formation of amines. While treatment with hydrazine expanded the surface area of the mildly oxidized sample, in the case of strongly oxidized graphite only surface chemistry was affected and a significant amount of nitrogen was introduced to it. Creation of porosity after reduction did not enhance ammonia adsorption due to the absence of reactive oxygen (epoxides) sites.     

Synthesis of thermo- and pH-responsive polysilsesquioxane with carboxylic acid group

The thermoresponsive polysilsesquioxanes containing N-(methoxyethyl)methylamide structures with carboxylic acid groups were newly prepared. In the syntheses of the polysilsesquioxanes, the silane coupling reagent, obtained from the reaction of (3-isocyanatopropyl)trimethoxysilane and (2-methoxyethyl)methylamine, was used for the co-condensation with (3-mercaptopropyl)trimethoxysilane to give the polysilsesquioxane with mercapto group (MMEPSQ). MMEPSQ was employed as the intermediary compound to introduce carboxylic acid group through thiol-ene reaction. The polysilsesquioxane, which was prepared from the reaction of MMEPSQ and methacrylic acid showed the expected amphiphilic and thermoresponsive properties in an aqueous solution with addition of sodium hydroxide. The lower critical solution temperature (LCST) owing to hydrophobic aggregation increased with pH value of the aqueous solution. Furthermoe, the use of MMEPSQ for the reactions with maleic anhydride and successive ring-opening reaction by the amines, which contained pyridine or 15-crown-5-ether ring, enabled the formations of multi-functionalized polysilsesquioxanes. In the case of the polysilsesquioxane containing carboxylic acid groups and pyridine rings, the pyridinium salt structure was favorable to keep an enough solubility in water and the reversible thermoresponsive behavior. The polysilsesquioxane containing the crown ether and carboxylic acid groups, the selective ion recognition property to alkali metal ion was observed.     

Thermal condensation of fatty acids and amines with proteins

Useful, potentially low cost, polypeptide surfactants were prepared directly from the thermal condensation (ca. 240 C, ca. 1 hr) of proteins (wool, vegetable protein, gelatin, and chicken feather) with long chain fatty acids (undecylenic, lauric, and stearic) or fatty amines (dodecylamine and N-[γ-aminopropyl] dodecylamine). Dilute aqueous solutions of these surfactants, at appropriate pHs, exhibit good foaming characteristics and low surface tensions. The condensation reaction is envisioned as a transamidification in which terminal anionic groups (carboxylic acid from fatty acids) or cationic groups (primary amino from fatty amines) are produced according to the following reactions     

Hochreaktive Trialkylsilylierungsreagentien aus Bis(trifluormethansulfonyl)imid – Silylierung von funktionellen Gruppen,alkinen und reaktiven Aromaten

Highly Reactive Trialkylsilylation Reagents Derived from Bis(trifluoromethanesulfonyl)imide – Silylation of Functional Groups, Alkines and Reactive Aromatics The synthesis of trialylsilyl-bis(trifluormethane-sulfonyl)imides 3 is described. Compounds 3 with bulky trialkylsilyl groups 3a,b only exist in the silatautomeric form 3a′, b′ under usual conditions, 3c in the N-trimethylsilyl structure. Despite of the bulky silyl substituents in 3a′, b′ their reactivity is higher than of trimethylsilyltriflate. Alcohols, carbonyl compounds, nitroalkanes and carboxylic acid esters are silylated in good yields, especially by the more reactive triisopropylsilyl derivative 3b ′ in presence of tertiary amines. tert.-Butyl carboxylates and benzylcarboxylates are cleaved. Monosubstituted alkines and electron-rich (hetero) aromatics are carbosilylated in presence of N-ethyl-diisopropylamine.     

Synthesis of polyfunctional fatty amines from sophorolipid-derived 17-hydroxy oleic acid

A series of mono- and diamines and one triamine have been prepared using methyl 17-hydroxy oleate as the common starting material. The 17-hydroxy oleate is an abundant bioderived material obtained from acid alcoholysis of sophorolipids, which in turn are produced by fermentation of agricultural by-products. Incorporation of the amino unit(s) can be selectively performed at either end of the chain or at its middle. The chief synthetic reactions used are allylic bromination, Curtius rearrangement, and the Mitsunobu reaction. These fatty amines also possess functionality such as hydroxy groups, carboxylic acids, and C−C double bonds. The amines are isolated in protected form using a variety of protecting groups, the identities of which can be selected on the basis of the intended use of the amine. These novel compounds will be of interest in the preparation of highly functionalized polymers and surfactants, among other areas.     

Comparison of the kraft paper crosslinked by polymeric carboxylic acids of large and small molecular sizes: Dry and wet performance

Polycarboxylic acids have been used as crosslinking agents for wood pulp cellulose for improving paper wet strength. Our previous research showed that low‐molecular‐weight polymeric carboxylic acids are effective in improving paper wet strength retention and reducing its flexibility. In this research, we compared two polymeric carboxylic acids, that is, poly(maleic acid) (PMA) with M_n of 800 and poly(methyl vinyl ether‐co‐maleic acid) (PMMA) with M_n of 1,130,000 for improving paper wet strength. The kraft paper sheets were treated at a 2% acid level and cured at different temperatures. The dry strength, wet strength, and folding endurance of the treated sheets were measured. We found that PMA and PMMA have comparable effectiveness in improving paper wet strength and wet stiffness. However, the treatment with PMA increases paper brittleness and severely diminishes paper folding endurance, whereas the treatment with PMMA increases both the dry strength and folding endurance by enhancing the paper's toughness. This striking difference in the performance of the treated paper is attributed to the different nature of the crosslinkages formed on the sheets. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 907–912, 1999     

Functionally‐modified egg white albumen hydrogels

Hydrogels were prepared by using egg white albumen (EWA) before and after chemical modification of its lysyl residues with ethylenediamine tetraacetic dianhydride (EDTAD) to incorporate carboxylic groups. This resulted in an increase in swelling ratio of the EWA hydrogels. The swelling ratio increased dramatically in deionized water substantially, more than in pH 7.4 buffer solution. The effects of medium pH, temperature and swelling were investigated, along with crosslinking of the gel network by glutaraldehyde (GLA), as well as acetone treatment. The gels denatured by acetone showed an insignificant increase in swelling ratio for the gels crosslinked with GLA during gel preparation, which is in contrast to the gels crosslinked subsequent to gel formation. The swelling behavior was positively affected by temperature and time. However, an insignificant effect of pH was observed due to electrostatic screening of the carboxylic groups by sodium ions in the buffer solution. Availability of various functional groups on EWA has resulted in adsorption of metals (Cu⁺² ions) and non‐metals (PO₄^?2 anions). Copyright © 2004 Society of Chemical Industry     

Poly(n-butyl methacrylate) with primary amine end groups for supporting cell adhesion and proliferation of renal epithelial cells

Polymer coatings that support epithelial cell culture have been developed. Ozonolysis and subsequent workup of poly(butyl methacrylate-co-butadiene) copolymers is used to form oligomers with carboxylic acid end groups, which are then further reacted with diamines to provide poly(butyl methacrylate)s with primary amine end groups. The polymers are cast as films and used as cell culture substrates for human dermal fibroblasts and human renal epithelial cells. Fibroblast and epithelial cells adhere and proliferate on acid functional materials but on amine functional films epithelial cells show greater viability than fibroblasts.     

Method for the determination of primary,secondary, and tertiary amino groups in star‐shaped polyamide 12 with a poly(ethylene imine) core

A star‐branched poly(ethylene imine)‐g‐polyamide 12 with a high concentration of primary amino end groups is an object of interest for future chemical modifications. In many cases, the concentration of primary amino groups, which are also the end groups of the polyamide 12 arms, and the concentrations of secondary and tertiary amino groups in a sample need to be known independently. Because of the difference in the reactivity of phthalic acid toward amino groups, its reaction with poly(ethylene imine)‐g‐polyamide 12 can be used for the analytical determination of these groups. With primary amino groups, phthalic acid forms phthalimido moieties, which are detectable by IR spectroscopy. The IR bands can be used for quantitative analysis with an appropriate calibration procedure. The concentration of primary amino groups can also be calculated as the difference between the concentration of all types of amino groups before the reaction with phthalic acid and the final concentration of amino and carboxylic groups after the reaction. The final concentration of the amino groups is equal to the concentration of unreacted tertiary amino groups after the reaction with phthalic acid anhydride. The difference between the final concentration of carboxylic groups and the initial concentration of carboxylic groups is equivalent to the concentration of secondary amino groups, which react with phthalic acid to form phthalamido acid moieties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 556–563, 2005     

Improvement of plybond strength of paperboard by corona treatment

It was found that the treatment of the surfaces of wet pulp sheets (moisture content; up to 85%) in a corona discharge improved greatly the plybond strength of the paperboard obtained when the treated wet pulp sheets were laminated together, pressed, and then dried. Treatment was carried out by use of a corona apparatus which had variable driven roll electrodes for transporting the wet pulp sheets through a corona field and was attached to a high-voltage generator (～ max 500 W, ～ 16 kV at 5 kHz). The plybond strengths of the paperboards were examined by means of Tappi RC-273 and JIS P8139 methods. Some experiments regarding the chemical effects of the corona treatment on the surface modification of wet pulp sheets were made with the aid of dye adsorption methods. Both untreated and corona-treated pulps adsorbed basic dyes, methylene blue, etc., with the same extent of dyeing. This indicates that no measurable acidic sites (carboxyl groups) increased on the surfaces of the pulp sheets during the corona treatment. To detect aldehyde groups, the dyeing examination of the pulps with Schiff's reagent was made, and the results showed a higher dyeing ability for the corona-treated pulps compared to the untreated, indicating that aldehyde groups on the pulp surfaces increased with an increase in the degree of corona treatment. The corona treatment seems to produce on the surface layer lightly oxidized and fairly degraded polysaccharide chains, which will tend to swell in water and thus act as an adhesive in plybonding the pulp sheets.     

Thermal reactions of fatty acids with diethylene triamine

The relative reactivities of the primary and secondary amino groups of diethylene triamine with fatty acids depend on the thermal reaction conditions. Without solvents, the primary amines are more reactive than the secondary amine for steric reasons, and the reaction results mainly in the 1,3-diamide. However, in dilute solution, the secondary amine shows higher reactivity than the primary amines, and the reaction proceeds probably by way of the 1,2-diamide, which forms imidazolines under much milder conditions than from the 1,3-diamide. The hydrolysis of imidazoline to the 1,2-diamide as the major product confirmed the higher reactivity of the secondary amine.     

Functionalization of surfactant wrapped graphene nanosheets with alkylazides for enhanced dispersibility

A facile and simple approach for the covalent functionalization of surfactant wrapped graphene sheets is described. The approach involves functionalization of dispersible graphene sheets with various alkylazides and 11-azidoundecanoic acid proved the best azide for enhanced dispersibility. The functionalization was confirmed by infrared spectroscopy and scanning tunneling microscopy. The free carboxylic acid groups can bind to gold nanoparticles, which were introduced as markers for the reactive sites. The interaction between gold nanoparticles and the graphene sheets was followed by UV-vis spectroscopy. The gold nanoparticle-graphene composite was characterized by transmission electron microscopy and atomic force microscopy, demonstrating the uniform distribution of gold nanoparticles all over the surface. Our results open the possibility to control the functionalization on graphene in the construction of composite nanomaterials.     

Linseed Oil‐Based Thermosets by Aza‐Michael Polymerization

Aza‐Michael addition on acrylated linseed oil (AELO) is performed to synthetize biobased bulk thermosets without any catalyst. First, acrylation of epoxidized linseed oil (ELO) allows to obtain acrylate functions with vicinal hydroxyl groups which enhance the reactivity of acrylates. The autocatalytic effect of hydroxyl groups on acrylate monomers is highlighted by kinetic studies monitored by NMR and FTIR analyses on model molecules. Then, Priamine 1071, amine terminated poly(propyleneoxide) (PPO) and meta‐xylylenediamine (MXDA) are used as cross‐linkers with AELO. Curing kinetics are studied by DSC analyses to compare the reactivity of these structures. Priamine 1071 shows the highest reactivity; curing at room temperature is performed and high conversion is reached. Two enthalpies are observed with MXDA and only one at high temperature for PPO‐based materials. Thermosets with a large range of mechanical properties are finally obtained from soft materials with PPO‐diamine to hard materials with MXDA. Practical Applications: Thermosets are obtained by curing AELO with various diamines via aza‐Michael reaction. Model reaction allows to demonstrate catalytic effect of hydroxyl groups on Aza‐Michael reaction of acrylated oil with amines. Hence, linseed oil is a promising resource in terms of sustainable development in polymer science.     

Paper wet performance and ester crosslinking of wood pulp cellulose by poly(carboxylic acid)s

Poly(carboxylic acid)s have been used as crosslinking agents for wood pulp cellulose to increase the wet strength of paper. In this research, we evaluated the effects of two multifunctional carboxylic acids, i.e., 1,2,3,4-butanetetracarboxylic acid (BTCA) and poly(maleic acid) (PMA), on the wet strength retention, dimensional stability, wet stiffness, and folding endurance of the treated paper. We observed that the wet strength retention, dimensional stability, and wet stiffness of the treated sheets increase, whereas the folding endurance decreases as the poly(carboxylic acid) concentration applied to those sheets increases. We measured the ester carbonyl band absorbance in the spectra of the treated paper. The linear correlation between the ester carbonyl band absorbance and wet strength, dimensional stability, and wet stiffness indicates that the improvement in the wet performance of the treated paper is directly attributed to the ester crosslinking of the wood pulp cellulose by poly(carboxylic acid)s. The data presented in this article also indicate that FTIR spectroscopy can be used for predicting the performance of the paper crosslinked by poly(carboxylic acid)s. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 649–658, 1998     

Lineare Tensidalkohole aus Olefinen mit innenständiger Doppelbindung

Linear Tenside Alcohols from Olefines with Inner Double Bond The reaction of olefines with carbon monoxide and methanol in presence of the catalyst system cobalt/pyridine, called hydrocarboxymethylation, leads to carboxylic acid methylesters with a fatty acid rest which is 1 C-atom longer in comparison to the initial olefine. The influence of various reaction parameters on space-time yield and selectivity and linearity or distribution of the products is demonstrated in the example of linear and branched olefines with terminal and internal double bond. The hydrocarboxymethylation procedure which easily gives access to alcohols, carboxylic acids and amines of the tenside range (C₁₂-C₁₈) by the carboxylic acid methyl esters, is compared with other methods for production of tenside raw materials (Ziegler-Alfol process, conventional and modified hydroformylation, process on native basis).     

苯乙烯臭氧化一步法合成苯甲醛的研究

两性离子是臭氧化反应过程的活性中间体,本实验采用水或有机胺捕获苯乙烯臭氧化生成的两性离子,不经臭氧化物中间体及传统的还原分解反应一步法合成苯甲醛。考察了溶剂种类、溶剂用量、反应温度、臭氧流量和添加剂种类等因素对反应的影响。实验结果表明,水捕获两性离子的活性大于有机胺,不同有机胺的反应活性不同：三乙胺>三正丁胺>三正辛胺,叔胺>仲胺。较佳的反应条件(以0.05 mol苯乙烯计)为：溶剂丙酮25.0 mL,反应温度0~5℃,臭氧流量200 mL•min-1,n(水)：n(苯乙烯)=3:1。在该条件下,重复实验三次,所得苯甲醛的平均收率为96.5%。