M. Mercedes Pastor-Blas

• Professor
• University of Alicante

The catalytic hydrogenation of the toxic and harmful p-chloronitrobenzene to produce the value-added p-chloroaniline is an essential reaction for the sustainable chemical industry. Nevertheless, ensuring satisfactory control of its chemoselectivity is a great challenge. In this work, a N/S co-doped metal-free carbon catalyst has been fabricated by...

Metal-free catalysts based on nitrogen-doped porous carbons were designed and synthesized from mixtures of melamine as nitrogen and carbon sources and calcium citrate as carbon source and porogen system. Considering the physicochemical and textural properties of the prepared carbons, a melamine/citrate ratio of 2:1 was selected to study the effect...

Polypyrrole (PPy) has been prepared by oxidative polymerization of pyrrole and used as a raw material for the preparation of N-doped activated carbons. Thus, PPy has been pyrolyzed at 900 °C and then activated with steam under different activation conditions (time and temperature). This has allowed for the preparation of activated carbons with diff...

The catalytic reduction of nitrites over Pt-In catalysts supported on activated carbon has been studied in a semi-batch reactor, at room temperature and atmospheric pressure, and using hydrogen as the reducing agent. The influence of the indium content on the activity and selectivity was evaluated. Monometallic Pt catalysts are very active for nitr...

In-situ hydrodeoxygenation of guaiacol over Ni-based nitrogen-doped activated carbon supported catalysts is presented in this paper as an economically viable route for bio-resources upgrading. The overriding concept of this paper is to use water as hydrogen donor for the HDO reaction, suppressing the input of external high-pressure hydrogen. The ef...

The hydrogenation of nitroarenes to produce the corresponding amines using dihydrogen as reductant has an important industrial role since it allows to obtain important added-value products. This reaction needs the...

“H2-free” HDO is a revolutionary route to circumvent the limitations of H2-fed HDO reactors for biomass upgrading. This work demonstrates the viability of this economically appealing route when an adequate catalyst is implemented. Herein, we have developed a new family of Pt catalysts supported on N-doped activated carbons for the H2-free HDO proce...

A mechanism for the reduction of aqueous nitrate with metal-free polypyrrole (PPy) is proposed. The activity and selectivity of the polymer has been compared to those of metal catalysts supported on polypyrrole, activated carbon or titania (TiO2). The role of formic acid (FA) and hydrogen (H2) as reductants, and carbon dioxide (CO2) as buffer of th...

Materials able to produce the reduction of nitrate from water without the need of a metal catalyst and avoiding the use of gaseous hydrogen have been developed by combining the synergistic properties of titania and two conducting polymers. Polymerization of aniline and pyrrol on titanium dioxide in the presence of two different oxidants/dopants (ir...

Platinum nanoparticles have been synthesized on polyaniline (PANI) and polypyrrole (PPy) as supports using H2PtCl6 as metal precursor and a reducing treatment with cold Ar plasma. The catalytic activity of the polymer-supported catalysts in the reduction of aqueous nitrate with H2 at room temperature was evaluated. These systems are able to conside...

The Cover Feature shows the application of an easily prepared ultrafine ruthenium nanocatalyst to both the organosilane oxidation and the oxygen evolution reactions. In their Communication, E. S. Gnanakumar et al. describe the facile and general preparation of monodispersed superior ruthenium metal catalysts by using a plasma-assisted synthesis at...

The effect of Ar plasma treatment on the catalytic performance of Pt/CeO2 has been studied. The catalyst was activated using different procedures separately or in combination: calcination, reduction under pure H2 and cold Ar plasma treatment. The resulting materials were characterized by X-ray photoelectron pectroscopy, X-ray adsorption near edge s...

We report a facile and general approach for preparing ultrafine ruthenium nanocatalysts by using a plasma-assisted synthesis at <100 °C. The resulting Ru nanoparticles are monodispersed (typical size 2 nm) and remain that way upon loading onto carbon and TiO2 supports. This gives robust catalysts with excellent activities in both organosilane oxida...

Three different conducting polymers, polythiophene (PT), polypirrol (PPY) and polyaniline (PANI) have been synthesized via oxidative chemical polymerization in aqueous media, in such a way that the synthesis protocol did not involve any toxic solvents. They have been tested in the abatement of nitrates from an aqueous solution without the need of a...

Pt and Pt/Sn catalysts supported on polypyrrole (PPy) have been prepared using Ar plasma to reduce the metal precursors dispersed on the polymer. The PPy support was synthesized by chemical polymerization of pyrrole with FeCl3·6H2O, this leading to the conducting form of the polymer (conductimetric measurements). The Ar plasma treatment produced a...

Supported metals are traditionally prepared by impregnating a support material with the metal precursor solution, followed by reduction in hydrogen at elevated temperatures. In this study, a polymeric support has been considered. Polypyrrole (PPy) has been chemically synthesized using FeCl3 as a doping agent, and it has been impregnated with a H2Pt...

CO2 plasma treatment modifies the surface of VR rubber but due to some ingredients in the rubber formulation that migrate to the adhesive joints preventing adhesion, a reinforcement of the adhesive joint by isocyanate has been considered. Thus, an isocyanate wipe has been performed right after plasma treatment and isocyanate has also been incorpora...

The grafting of natural halloysite nanotubes (HNT) with aminosilanes exhibiting two (DAS) and three (TAS) amino groups has been investigated and compared to the physisorption of both silanes on halloysite nanotubes. Halloysite nanotubes were used as solid support for the heterogeneous Atom Transfer Polymerization of methyl methacrylate (MMA) into p...

A parent activated carbon (C-0) was subjected to four different treatments: (i) heat treatment at 1273K in Ar (C-1); (ii) heat treatment at 473K in air (C-2); (iii) oxidation with H2O2 (C-3) and, (iv) oxidation with HNO3 (C-4). These materials were evaluated as supports of CuBr–[1,1,4,7,10,10-hexamethyltriethylenetetramine] (CuIBr–HMTETA), a cataly...

En el nuevo Grado en Química, la asignatura Introducción a la Ciencia de los Materiales prestará la mayor parte de sus contenidos a la asignatura del segundo curso Sólidos Inorgánicos. El trabajo colaborativo es una metodología docente que permite al alumnado aprender no solo contenidos relacionados con las asignaturas, sino también desarrollar hab...

The effectiveness of nitrogen, oxygen and air Radio Frequency (RF) plasma treatments on two styrene-butadiene vulcanized rubbers with a different formulation has been studied. The presence of an antiadherent surface layer containing low-molecular weight ingredients (sulfur-rich vulcanization agents and wax) from SW (Sulfur-Wax) rubber formulation r...

Three activated carbons exhibiting different textural characteristics were considered as support for CuBr–HMTETA catalyst in the Atom Transfer Radical Polymerization (ATRP) of methyl methacrylate. The pore distribution of the activated carbons played an important role in the control of the polymerization reaction: polydispersity index always failed...

Nanotubes of natural halloysite (HNTs) were used as a solid support for the heterogeneous atom transfer polymerization of methyl methacrylate (MMA) into poly(methylmethacrylate) (PMMA) using adsorbed CuBr–[1,1,4,7,10,10-hexamethyltriethylenetetramine] (CuBr–HMTETA) and CuBr–[3-(2-aminoethylamino)propyltrimethoxysilane] (CuBr–AEAPTS) as catalysts. C...

Traditionally, it has been believed that there is an incompatibility between the chlorinated rubber surface and polychloroprene adhesives resulting in a lack of adhesion. However, in this study it has been shown that a polychloroprene adhesive (PCP30P) produces similar T-peel strength values when using a polyurethane (PU) adhesive in joints produce...

The effect of addition of isocyanate to a polyurethane adhesive has been investigated. Polyurethane adhesive was used for bonding a thermoplastic (TR) and a vulcanized (VR) synthetic butadiene‐styrene rubber. CO 2 plasma treatment has oxidized the rubber surfaces, increasing surface energy (wettability), roughness, and favoring mechanical interlock...

The interface produced between a chlorinated thermoplastic styrene-butadiene-styrene rubber and a polychloroprene (PCP) adhesive has been studied and compared to the interface produced using a polyurethane (PU) adhesive. Chlorination of the rubber was produced by spin coating solutions of trichloroisocyanuric acid in methyl ethyl ketone. The adhesi...

The surface modifications produced by a RF plasma treatment on a thermoplastic styrene–butadiene–styrene rubber–SBS—with a considerable amount of processing oils in its formulation (TRO) have been studied and compared to the modifications produced on an oil-free SBS rubber (TRF). The modifications produced by the plasmas on the rubber surface depen...

As environmental friendly alternative to the halogenation treatment with trichloro isocyanuric acid solutions in organic solvents (TCI/MEK), in this study a water-based surface treatment for rubber materials based in chloramine T aqueous solutions has been proposed. It was found that the effectiveness of chloramine T (CT) (N-chloro-sodium-p-toluene...

IntroductionExperimental MaterialsExperimental TechniquesResults and DiscussionConclusions MaterialsExperimental Techniques

The effect of exposure to different ozone concentrations, in conjunction with UV radiation, on the surface modification and adhesion properties of a block synthetic styrene-butadiene-styrene (S6) rubber was studied. The treatment time varied between 10 s and 30 min. Three different surface treatments were investigated: ozone only (O3), UV radiation...

Corona discharge and ultraviolet (UV) radiation treatments have been used as environmental friendly alternatives to the common surface treatment of halogenation for a styrene–butadiene–styrene (S6) rubber. The corona energy and the length of treatment under UV radiation of the S6 rubber have been studied and the surface modifications produced have...

Solutions of trichloroisocyanuric acid (TCI) in different organic solvents are commonly employed in the footwear industry to improve the adhesion of SBS (styrene-butadiene-styrene) rubber soles to polyurethane adhesive. To avoid the use of organic solvents in the chlorinating solutions, several water-based chlorinating treatments were investigated...

To improve the adhesion properties of styrene–butadiene–styrene (SBS) rubber sole to polyurethane adhesive, surface treatments are required, of which halogenation with trichloroisocyanuric acid (TCI) solutions in organic solvents is the most commonly used treatment in the footwear industry. Calcium carbonate filler is commonly added to improve the...

The surface modifications produced by treatment of a synthetic vulcanized styrene-butadiene rubber (R1) with oxidizing (oxygen, air, carbon dioxide) and nonoxidizing (nitrogen, argon) RF plasmas have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the treatment depended on the gas atmosphere u...

Avoidance of solvents in bonding operations is a current demand in the footwear industry. Halogenation of rubber soles with solutions of trichloroisocyanuric acid (TCI) in different solvents has been successfully used to improve bonding to the leather uppers. In this study, the use of chlorine bleach as an alternative water surface treatment for a...

A styrene–butadiene–styrene (S6) rubber was treated with corona discharge to increase its surface energy and adhesion to polyurethane (PU) adhesive. The influence of the length of treatment (the speed of the upper plate was varied from 80 to 900cm/min) during corona discharge was analyzed. The corona energy applied to S6 rubber surface ranged from...

The chlorine concentration in trichloroisocyanuric acid (TCI) solutions depended on the solvent used to apply the chlorination agent on the rubber surface and on the time after preparation of the solutions. In this study, methyl ethyl ketone (MEK) and ethyl acetate (EA) have been used as solvents for 2 wt% TCI in the treatment of a difficult-to-bon...

The effectiveness of the treatment with ultraviolet light (UV) on several polymeric surfaces has previously been established. In this study, a low pressure mercury vapour lamp was used as a source of UV radiation for the surface treatment of a difficult-to-bond block styrenebutadiene-styrene rubber (S6), the treatment time ranging from 10 s to 30 m...

Chlorination of a thermoplastic styrene-butadiene-styrene rubber (S0) with a solution of 2 wt% trichloroisocyanuric acid (TCI) in ethyl acetate improved its adhesion to polyurethane adhesives. The analysis of the failed surfaces (obtained after T-peel test of S0/PU joints) showed that the locus of failure in the rubber/polyurethane joints progresse...

The effectiveness of chlorination as surface treatment to improve the adhesion of synthetic vulcanized styrene-butadiene rubber (SBR) depends on several experimental variables. Solutions of trichloroisocyanuric acid (TCI) in methyl ethyl ketone (MEK) have been used as effective chlorination agents for several rubbers. In this study, the influence o...

A water-based chemical treatment based on sodium dichloroisocyanurate (DCI) solutions for rubber soles of different natures was studied. The effects produced by treatment of the rubber soles with DCI were compared with the standard halogenation method using trichloroisocyanuric acid (TCI) solutions in an organic solvent. It is found that the aqueou...

The surface modifications of a synthetic vulcanized styrene-butadiene rubber (R1) using a chemical treatment [halogenation with trichloroisocyanuric acid (TCI)] and a treatment with oxygen plasma were compared. Treatment of R1 rubber with 2 wt% TCI produced greater surface modification than the oxygen plasma and the modification was extended over a...

Chlorination of a thermoplastic styrene-butadiene-styrene rubber (S0) with different amounts of trichloroisocyanuric acid (TCI) solutions in ethyl acetate improved its adhesion to polyurethane adhesives. A strong interaction of the PU (polyurethane) adhesive and the chlorinated S0 rubber chains is produced at the interface. The increase in the conc...

In this study, it was shown that the degree of effectiveness produced by halogenation with trichloroisocyanuric acid (TCI) was influenced by previous methyl ethyl ketone (MEK) wiping of a synthetic vulcanized styrene-butadiene rubber (R2) surface. The MEK wiping of the R2 rubber surface prior to chlorination with TCI removed the paraffin wax layer...

Chlorination of a synthetic vulcanized styrene–butadiene rubber with 0.5 wt% trichloroisocyanuric acid (TCI) solutions in butanone was carried out. The durability of the halogenation treatment on the surface properties of rubber was assessed using contact angle measurements, attenuated total multiple reflection method (ATR-IR) spectroscopy and SEM....

Ethyl, propyl and butyl acetates (EA, PA, BA, respectively) were used as solvents for trichloroisocyanuric acid (TCI) to chlorinate styrene–butadiene rubber (SBR). Characterization of the treated surfaces was carried out using ATR-IR spectroscopy, scanning electron microscopy (SEM), and contact angle measurements. Stress-strain measurements were al...

Two different surface treatments have been applied to a synthetic vulcanized styrene-butadiene rubber (R1): corona discharge and UV treatment. Corona discharge treatment has been carried out on R1 rubber by varying the electrode-sample distance (2–4 mm), the duration (1 to 11 sec) and several parameters in the treatment of R1 rubber with UV treatme...

A low-pressure gas RF plasma-treatment has been used to improve the adhesion of a synthetic vulcanized rubber to polyurethane adhesive as an environmentally friendly alternative surface treatment to the conventional chemical treatments. A sulfur vulcanized styrene-butadiene rubber (R2) containing a noticeable amount of zinc stearate and paraffin wa...

Three thermoplastic block styrene–butadiene–styrene (TR) rubbers were treated with sulfuric acid to improve their adhesion to polyurethane adhesives. T-peel test, scanning electron microscopy (SEM), contact-angle measurements (water, ethane diol), infra red spectroscopy (ATR-IR) and stress–strain experiments were used to analyze the nature of surfa...

A synthetic vulcanized styrene-butadiene rubber (R2) was used in this study. The presence of paraffin wax and zinc stearate in the rubber composition prevented the adhesion of R2 rubber to solvent-based polyester-urethane adhesive. To increase the adhesion properties of R2 rubber, a surface treatment with sulfuric acid (cyclization) was applied, an...

The effectiveness of the chlorination treatment of synthetic vulcanized styrene-butadiene rubbers is determined by several experimental variables. In this study, trichloroisocyanuric acid (TCI) solutions in butanone have been used as chlorinating agents for a difficult-to-bond vulcanized styrene-butadiene rubber (R2). The influence of the TCI conce...

The peel strength of oxygen plasma-treated rubber/polyurethane adhesive joints was measured as a function of the length of the treatment. The trend obtained did not obey the expected mechanisms of adhesion and therefore the precise determination of the locus of failure of the joints was carried out using XPS and infrared attenuated total reflectanc...

Modifications produced on a vulcanized styrene –butadiene rubber surface by treatment with sulfuric acid were studied and several experimental variables were considered.The treatment of R1 rubber with sulfuric acid produced a noticeable decrease in contact angle which was mainly ascribed to an increase in surface energy due to the formation of sulf...

The chlorination of vulcanized styrene-butadiene rubbers (SBRs) with trichloroisocyanuric acid (TCI) has been studied. The solvent used to apply the TCI chlorinating solutions on the rubber plays an important role in the effectiveness of the treatment since the solvent determined the degree of penetration of TCI into the rubber and also different c...

In order to improve their adhesion to polyurethane adhesives, three unvulcanized block styrene-butadiene-styrene (SBS) rubbers with styrene contents between 33% and 55% were surface-treated with solutions of 2 wt% trichloro-isocyanuric acid (TCI) in ethyl acetate. The joint strength was estimated using T-peel tests and the failed surfaces were anal...

The surface of a synthetic vulcanized styrene–butadiene rubber (R2) was treated in an oxygen plasma to improve adhesion in joints prepared with a one-component solvent-based polyester–urethane adhesive. The modifications produced on the rubber surface by plasma treatment were assessed using advancing and receding contact angle measurements, x-ray p...

Three polyurethane elastomers (PU) containing different hard/soft (h/s) segment ratios were prepared. The PUs were characterized using Gel Permeation Chromatography (GPC), DSC, Wide Angle X-ray Diffraction (WAXD). Dynamic Mechanical Thermal Analysis (DMTA), and Stress-controlled rheometry. The surface properties were evaluated from contact angle me...

The surface of a sulfur-vulcanized synthetic styrene-butadiene rubber (SBR) was treated with ethyl acetate solutions containing different amounts of trichloroisocyanuric acid (TCI). The chlorinated SBR surfaces were characterized using contact angle measurements (water, ethane diol, n-hexadecane), infra-red (IR) spectroscopy and XPS. Chlorination p...

The surface of an unvulcanized styrene-butadiene-styrene (SBS) rubber (S0) was chlorinated with 0.5–7wt% trichloroisocyanuric acid (TCI) solutions. The adhesion strength of surface-treated SO rubber/polyurethane adhesive joints was obtained from T-peel tests. The failed surfaces after peeling were characterized by ATR-IR spectroscopy, contact angle...

A sepiolite silicate was heat-treated at 550 and 1000°C to modify its structure, and was used as a filler in a solvent-based polyurethane (PU) adhesive. The treated sepiolites were characterized by X-ray diffraction and infra-red spectroscopy, and it was observed that the water was irreversibly removed from the structure and pores of the sepiolite,...

A synthetic vulcanized styrene-butadiene rubber (R) was treated with a halogenation agent (TCI = trichloroisocyanuric acid) to produce improved adhesion (i.e. high T-peel strength) in joints prepared with a one-component, solvent-based polyester urethane adhesive. Several amounts (0.5 to 7 wt%) of TCI solutions in ethyl acetate were applied to the...

Three elastomeric polyurethanes were obtained by reacting MDI (diphenylmethane-4,4′-diisocyanate) with ϵ-caprolactone macroglycols of different molecular weight (1000–3000 daltons); the chain extender used was 1,4-butane diol. The increase in the molecular weight of the macroglycol modified the degree of phase separation and the interactions betwee...

Fumed silica is a well-known mineral filler of epoxy and polyurethane adhesives. Although effective, the small particle size and the relative high cost of fumed silicas suggest the need for an alternative filler. In this study, the usefulness of adding a natural hydrated magnesium silicate (sepiolite) as a new filler in solvent-based polyurethane (...

Different amounts (5-30 wt% with respect to the polyurethane content in the adhesive) of a new filler, a partially defibrillated natural hydrated magnesium silicate (sepiolite), were added to solvent-based polyurethane (PU) adhesive formulations. The rheological, mechanical, surface, and adhesion properties of the PU adhesives obtained were measure...

The nature and formulation of two synthetic sulfur-vulcanized styrene-butadiene rubbers affected the extent, but not the nature, of the surface modification produced by halogenation with different amounts (1-7 wt%) of trichloroisocyanuric acid (TCI) solutions in ethyl acetate. R1 rubber had a low oil and plasticizer content, whereas R2 rubber conta...

Oxalic acid (OA) solutions in butanone/alcohol mixtures were used as surface treatment of synthetic vulcanized styrene-butadiene rubber (SBR). Several experimental variables were considered (OA concentration, nature and amount of the alcohol in the solvent mixture, roughening of rubber). The treatment with oxalic acid increases the T-peel strength...

In this paper two kinds of weak boundary layers (WBL) in synthetic vulcanized styrene-butadiene rubber are described. i) WBL produced by the presence of antiadhesion compounds of the rubber formulation (zinc stearate, microcrystalline paraffin wax). These WBL cannot be effectively removed by solvent wiping, whether followed by washing with an ethan...

Five one-component solvent-based adhesives (series C) prepared from ε-polycaprolactone polyurethane (PU) polymers were used to join unchlorinated and chlorinated synthetic vulcanized styrene-butadiene rubber. PU films were characterized by infra-red (i.r.) spectroscopy, differential scanning calorimetry (d.s.c.), wide angle X-ray diffraction (WAXD)...

Surface modifications produced by treatments (mainly halogenation) of synthetic vulcanized styrene-butadiene rubber (SBR) leading to increased adhesion properties with polyurethane adhesives have been studied. T-peel tests, scanning electron microscopy (SEM), advancing contact angle measurements, infra-red (IR) spectroscopy, X-ray photoelectron spe...