Crosslinking of cotton cellulose in the presence of serine and glycine. I. Physical properties and reaction kinetics

Serine and glycine were used to combine with dimethyloldihydroxyethyleneurea (DMDHEU) as crosslinking agents to study the physical properties of the crosslinked fabrics and the reaction kinetics, and find that the bound nitrogen is in the series of DMDHEU ? DMDHEU‐serine > DMDHEU‐glycine at the same resin concentration. The results also show that the wet crease recovery angle (WCRA) value of the treated fabrics for the three crosslinking agent systems is in the series of DMDHEU‐serine > DMDHEU‐glycine > DMDHEU alone at a given dry crease recovery angle (DCRA). The DCRA values of the treated fabrics for DMDHEU alone are higher than those for DMDHEU‐α‐amino acids for a given value of tensile strength retention (TSR). WCRA values for the various treated fabrics is in the rank of DMDHEU‐serine > DMDHEU alone > DMDHEU‐glycine at the same TSR. Rate constants for the various crosslinking agents are in the series of DMDHEU‐glycine > DMDHEU‐serine > DMDHEU alone at the given heated temperatures. Energies needed to crosslink and the values of enthalpies and entropies of activation are all DMDHEU‐glycine > DMDHEU‐serine > DMDHEU alone. Infrared ray (IR) spectra strongly suggest the reaction between DMDHEU and serine and the reaction between the hydroxyl group (cellulose) and serine can occur in the pad‐dry‐cure process, but only a little for the latter. The reaction between the functional groups of serine and the aluminum ion to form a complex also confirm with IR spectrum. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 595–603, 2005     

Degree of crosslinked cotton cellulose with prereacted DMDHEU–AA

Dimethyloldihydroxyethyleneurea (DMDHEU) and acrylic acid (AA) were used to synthesize the dimethyloldihydroxyethyleneurea–acrylic acid product (DMDHEU–AA, mole ratios of DMDHEU/AA = 1/0, 1/1, and 1/2, respectively). Cotton fabrics were treated with the various prereacted DMDHEU–AA products by changing resin concentrations in the bath. We found that the dry crease recovery angle (DCRA) and wet crease recovery angle (WCRA) of the treated fabrics increased with the increase of acrylic acid in the prereacted DMDHEU–AA at the same value of resin concentration in the bath, whereas the tensile strength retention (TSR) showed the inverse tendency. For a given value of number of crosslinks per anhydroglucose unit (CL/AGU), the DCRA and WCRA values of the DMDHEU–AA‐treated fabrics were higher than those for DMDHEU‐treated fabrics. Additionally, agent distribution and the reaction between –COOH of the crosslinking agent and cellulose molecule were also investigated in this study. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1580–1586, 2001     

Physical properties of crosslinked cellulose catalyzed with nano titanium dioxide

Four different carboxylic acids, 1,2,3,4‐butane tetracarboxylic acid (BTCA), maleic acid (MA), succinic acid (SUA), and citric acid (CA), were used as crosslinking agents to treat cotton fabrics in the presence of nanometer titanium dioxide (TiO₂) as a catalyst under UV irradiation. The dry crease recovery angle (DCRA) and wet crease recovery angle (WCRA) values of the treated fabrics were ranked BTCA > MA > CA > SUA and the tensile strength retention (TSR) values were ranked BTCA < MA < CA < SUA at a given resin concentration, catalyst concentration, and irradiation time period. The physical properties of the treated fabrics for nanometer silver/nanometer titanium dioxide (Ag/TiO₂) catalyst showed the same tendency. At a given DCRA, the WCRA values were ranked in the order BTCA ≒ MA > CA ≒ SUA; and at a given value of the TSR, the WCRA and DCRA values were both ranked in the order BTCA > MA > CA > SUA. The softness values of the carboxylic acid treated fabrics in the presence of nanometer TiO₂ catalyst were all better than that of the untreated fabric. Surface deposition of the treated fabrics for BTCA, which contains one vinyl double bond and four carboxylic acid groups, was higher than that for CA, which contains no vinyl double bond. IR spectra and electron spectroscopy for chemical analysis survey spectra showed the ester bond crosslink between the cellulose molecule and the various acids used in this study. The values of DCRA, WCRA, and add‐on of the CA crosslinked fabrics for the mixed catalysts were in the order ZrO₂/TiO₂ < SiO₂/TiO₂ < Ag/TiO₂. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2450–2456, 2005     

Crosslinking of cotton cellulose in the presence of alkyl diallyl ammonium salts. I. Physical properties and agent distribution

We used three kinds of alkyl diallyl ammonium salts (methyl, ethyl, and propyl) in combination with dimethyloldihydroxyethyleneurea (DMDHEU) as crosslinking agents. The nitrogen content, dry crease recovery angle (DCRA), moisture regain, and wicking height for the DMDHEU/alkyl diallyl ammonium salts were in the order of ? CH₃ > ? C₂H₅ > ? C₃H₇, but the wet crease recovery angle (WCRA) and tensile strength retention (TSR) were in the opposite order at the same resin concentration. For the same DCRA and TSR, the WCRA values for only DMDHEU were lower than those for DMDHEU/alkyl diallyl ammonium salts, and the WCRA values for DMDHEU/alkyl diallyl ammonium salts were in the order of ? C₃H₇ > ? C₂H₅ > ? CH₃. Both the ? OH group of the cellulose and DMDHEU could react with the vinyl or epoxy groups of the alkyl diallyl ammonium salts during the pad–dry–cure process. The surface migration for DMDHEU/alkyl diallyl ammonium salts was in the order of ? CH₃ > ? C₂H₅ > ? C₃H₇. Fabrics treated with DMDHEU/alkyl diallyl ammonium salts showed good antibacterial properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1662–1669, 2003     

Pore and crosslinking structures of cotton cellulose crosslinked with DMDHEU‐maleic acid

Two dicarboxylic acids (maleic acid and tartaric acid) were used in conjunction with DMDHEU as the crosslinking agents to treat cotton fabric samples. The treated fabrics then were dyed with direct red 81. The results show that the values of the dye absorption, equilibrium absorption, rate constants, and the pore index of structural diffusion resistance constant for the various crosslinking agents are ranked as DMDHEU‐tartaric acid > DMDHEU‐maleic acid > DMDHEU alone at the same dyeing temperature. The activation energies for the three crosslinked fabrics are in the rank of DMDHEU > DMDHEU‐maleic acid > DMDHEU‐tartaric acid. The CL length values for the various crosslinking agent systems are in the series of DMDHEU‐tartaric acid > DMDHEU‐maleic acid > DMDHEU alone for a given number of CL/AGU. The values of the pore index of structural diffusion resistance constant and dyeing rate constant are increased with the increase of CL length. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 143–148, 2005     

Crosslinking of cotton cellulose in presence of alkyl di‐allyl ammonium salts. III. Study on pore structure of treated fabrics from dyeing kinetics

Two kinds of alkyl di‐allyl ammonium salts (alkyl groups = methyl and propyl) as crosslinking agents are combined with dimethyloldihydroxyethyleneurea (DMDHEU) to study rate constants, structural diffusion resistance constants, and other parameters of dyeing. The dye absorptions for the various crosslinking agents are ranked DMDHEU–propyl di‐allyl ammonium salt > DMDHEU–methyl di‐allyl ammonium salt > DMDHEU, and the equilibrium absorption values are ranked DMDHEU–propyl di‐allyl ammonium salt > DMDHEU–methyl di‐allyl ammonium salt > DMDHEU. The dyeing rate constants and structural diffusion resistance constants of the finished fabrics are in the order DMDHEU–methyl di‐allyl ammonium salt > DMDHEU–propyl di‐allyl ammonium salt > DMDHEU; however, the activation energies are ranked inversely. The treated fabrics for DMDHEU–alkyl di‐allyl ammonium salts have a larger pore structure than those for DMDHEU. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 862–866, 2005     

Absorption of metal cations by modified B. mori silk and preparation of fabrics with antimicrobial activity

Silk fabrics were modified by treatment with tannic acid (TA) solution or by acylation with ethylenediaminetetraacetic (EDTA) dianhydride. Kinetics of modification with TA and acylation with EDTA–dianhydride was investigated. The physico‐mechanical properties of silk fabrics acylated with EDTA–dianhydride remained unchanged regardless of chemical modification. The absorption of metal cations (Ag⁺, Cu²⁺) by untreated and modified silk fabrics was studied as a function of the kind of modifying agent, weight gain, and pH of the metal solution. The absorption of Cu²⁺ at alkaline pH was not significantly influenced by chemical modification of the silk substrate. The absorption of Ag⁺ by acylated silk remained at a level as low as untreated silk, while was enhanced by TA. The higher the content of TA, the higher the absorption of Ag⁺. With respect to the pH of the metal solution, the acylation with EDTA–dianhydride enabled silk to absorb and bind metal cations even in the acidic and neutral pH range, where tannic acid had no effect. Medium to high levels of metal desorption were exhibited by untreated and modified silk fabrics towards the metal cations, with the only exception of the silk–tannic acid–Ag complex, which displayed an extraordinary stability. All metal‐containing silks exhibited significant antibacterial activity. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 297–303, 2001     

Physical properties and reaction kinetics of cotton cellulose crosslinked with dimethyloldihydroxyethyleneurea–maleic acid

Two dicarboxylic acids were used to join with dimethyloldihydroxyethyleneurea (DMDHEU) as crosslinking agents to treated cotton fabrics. These results reveal that the dry crease recovery angle values of the treated fabrics for DMDHEU–maleic acid are higher than those for DMDHEU–tartaric acid at a given wet crease recovery angle and tensile strength retention. The IR spectra show that the reaction between the –OH of DMDHEU and cellulose and the vinyl groups of maleic acids occurred. The cross section of the DMDHEU–maleic acid and DMDHEU–tartaric acid treated fibers and the energies of activation and other data of reaction kinetics for DMDHEU–maleic acid and DMDHEU–tartaric acid strongly suggest that the reaction of vinyl groups of maleic acid with cellulose molecules can take place during the pad/dry‐cure process. Additionally, the surface distribution of crosslinking agent on the finished fabrics for DMDHEU–maleic acid is slightly lower than that for DMDHEU–tartaric acid. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3886–3893, 2004     

Complexation studies of some newly synthesized precursors for substituted dibenzo and dibenzodiaza crown ethers

This study represents the synthesis of dibenzo and dibenzodiaza crown ether precursors with various functional groups in good yield by employing four different methods using polar protic and aprotic solvents with high boiling points. Also the complexation abilities of all synthesized ligands with Cu²⁺, Zn²⁺, and Ag⁺ were studied by conductometry; thus the conductometric behavior of Cu(NO₃)₂, ZnCI₂, and AgNO₃ in 80% dioxane–water mixture was investigated in the presence of these ligands. The order of formation constant for complexes of the ligands with Cu²⁺, Zn²⁺, and Ag⁺ ions was found to be: Cu²⁺ > Zn²⁺ > Ag⁺ for the ligands of VI , VII , XI , and XII ; Cu²⁺ > Ag⁺ > Zn²⁺ for the ligands of III and VIII ; and Zn²⁺ > Cu²⁺ > Ag⁺ for the ligands of I , II , IV , V , IX , and X . © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2497–2501, 2004     

Crosslinking of cotton cellulose in the presence of serine and glycine. II. Pore structures and agent distribution

Serine and glycine are selected as coreactants to combine with dimethylol‐dihydroxyethyleneurea (DMDHEU). We found that the pore structures of DMDHEU‐crosslinked cottons are changed. DMDHEU alone has lower values of equilibrium absorption, structural diffusion resistance constant, and rate constant, but higher value of activation energy than do DMDHEU–serine and DMDHEU–glycine. On the other hand, DMDHEU–serine has higher values of structural diffusion resistance constant and lower values of equilibrium absorption and rate constant than does DMDHEU–glycine; however, the hydroxyl group contained in serine has the higher affinity toward direct dye resulting in the decrease in the value of activation energy. The expansion patterns of cross section show that the degree of the expansion of the DMDHEU‐crosslinked fiber is lower than that of the DMDHEU–serine‐ and DMDHEU–glycine‐crosslinked fibers. The distribution of crosslinking agents on the crosslinked fabrics reveals the slightly higher surface distribution of DMDHEU–serine and DMDHEU–glycine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1578–1584, 2006     

Preparation and adsorption selectivity for Hg(II) and Ag(I) of chelating resin immobilizing benzothiazolyl group on crosslinked polystyrene via hydrophilic sulfur‐containing PEG spacer

A new chelating resin incorporating 2‐mercaptobenzothiazole (MBZ) into macroporous chloromethylated polystyrene via hydrophilic spacer of polyethylene glycol containing sulfur was synthesized. The resin was characterized by elementary analysis and infrared spectra. The adsorption capacity of the resin for Ag⁺, Hg²⁺, Cu²⁺, Zn²⁺, and Pb²⁺ as a function of pH was determined. The effects of interference ions, such as Na⁺, Mg²⁺, Ca²⁺, Ba²⁺, Cu²⁺, Zn²⁺, and Pb²⁺, on percent recovery were also investigated. The results showed that the resin could effectively remove Hg²⁺ and Ag⁺ from solutions containing a large excess of Na⁺, Mg²⁺, Ca²⁺, Ba²⁺, Cu²⁺, Zn²⁺, and Pb²⁺. In column operation, it was observed that Hg²⁺ and Ag⁺ in trace quantities were effectively removed from binary metal ions. The percent recovery of the resin for Hg²⁺ and Ag⁺ was >98.6% and >97.5%, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5034–5038, 2006     

A radiotracer study of durability of acrylic soil release polymers to laundering

Cotton/polyester fabrics were treated with ¹⁴C-labeled acrylic soil release polymers, either alone or with a durable press reagent, dimethyloldihydroxyethyleneurea (DMDHEU). Both two-bath and one-bath applications were used. Rate of removal of polymer in laundering was determined experimentally by radiotracer methods. Removal was faster in the order polymer alone (no DMDHEU) > two-bath process > one-bath process. The difference was much more significant when high molecular weight emulsion polymer was used than partially neutralized low molecular weight solution polymer. It is concluded that condensed DMDHEU serves as a coupling agent to bind polymer to fabric, thereby retarding removal of polymer in laundering. The significance of the results with respect to soil release of treated fabrics is discussed.     

Selective Extraction of Cu2+ and Ag+ Ions from Sulfuric Acid by Synergistic Combinations of Tetradentate Thia Macrocycles with Dioodecylnaphthalene Sulfonic Acid

Abstract

The aqueous-insoluble thia macrocycles tetrathia-14-crown-4 (TT14C4) and tetrathia-16-crown-4 (TT16C4) strongly and selectively synergize the extraction of Cu²⁺ and Ag⁺ ions from aqueous sulfuric acid solutions by the organophilic cation exchanger didodecylnaphthalene sulfonlc acid (HDDNS) in toluene diluent. Over a range of sulfuric acid concentrations, the selectivity is given by the order Ag² > Cu²⁺ > Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, and Zn²⁺, where synergism occurs only for Ag⁺ and Cu²⁺. Selectivity factors greater than 300 have been achieved for Cu²⁺ over ubiquitous Fe³⁺. The synergistic extraction of Cu²⁺ and Ag⁺ was explored as a function of sulfuric acid concentration, relative concentration of macrocycle vs. HDDNS, and loading.     

Synthesis,Characterization, and swelling behaviors of acrylic acid/carboxymethyl cellulose superabsorbent hydrogel by glow‐discharge electrolysis plasma

This article exploits a new approach for synthesis of acrylic acid/carboxymethyl cellulose (AA/CMC) superabsorbent hydrogel in aqueous solution by a simple one‐step using glow‐discharge electrolysis plasma, in which N,N′‐methylenebisacrylamide (MBA) was used as a crosslinking agent. The reaction parameters affecting the equilibrium swelling, that is, discharge voltage, discharge time, mass ratio of AA to CMC, content of crosslinker, and degree of neutralization, were systematically optimized to achieve a superabsorbent hydrogel with a maximum equilibrium swelling. The structure, thermal stability, and morphology of AA/CMC superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy. The swelling kinetics in distilled water and swelling behaviors in various pH solutions and salts solutions (NaCl, KCl, MgCl₂, CaCl₂, AlCl₃, and FeCl₃) were investigated in detail. The effect of six cationic salt solutions on the equilibrium swelling had the following order K⁺ > Na⁺ > Mg²⁺ > Ca²⁺ > Al³⁺ > Fe³⁺. In addition, the pH‐reversibility was preliminarily investigated with alternating pH between 6.5 and 2.0. The results showed that the equilibrium swelling of AA/CMC was achieved in 90 min. The hydrogel was responsive to the pH and salts, and was reversible swelling and deswelling behavior. POLYM. ENG. SCI., 54:2310–2320, 2014. © 2013 Society of Plastics Engineers     

π‐Complexation Studied by Fluorescence Technique: Application in Desulfurization of Petroleum Product using Magnetic π‐Complexation Sorbents

Abstract

Magnetic π‐complexation sorbents were studied for petroleum product desulfurization by fluorescent technique. The ability of metal cation to form π‐complexation decreases in the order following: Cu⁺>Ni²⁺>Co²⁺>Al³⁺. The order is consistent with that of desulfurization performance of their corresponding magnetic sorbents (γ‐Al₂O₃‐Cu(I)>γ‐Al₂O₃‐Ni(II)>γ‐Al₂O₃‐Co(II)>γ‐Al₂O₃). Both π‐complexation strength and desulfurization performance of the sorbents increase with temperature. The adsorptive performances of magnetic γ‐Al₂O₃‐Cu(I) sorbent to different compounds have the following orders: DBT>fluorene, and pyrene>naphthalene>benzene, respectively. In this study, dibenzothiophene (DBT) was used as a model sulphur‐containing compound for desulfurization. The maximal adsorption amount of magnetic γ‐Al₂O₃‐Cu(I), was 0.362 mmol DBT g^?1.     

Adsorption properties of novel chelating resins containing 2‐amino‐5‐methylthio‐1,3,4‐thiadizole and hydrophilic spacer arms for Hg2+ and Ag+

The adsorption properties, including the adsorption kinetics, adsorption isotherms, and adsorption selectivity, of newly formed chelating resins that contained a heterocyclic functional group and a hydrophilic spacer arm of poly(ethylene glycol) [polystyrene–diethylene glycol–2‐amino‐5‐methylthio‐1,3,4‐thiadizole (PS–DEG–AMTZ) and polystyrene–triethylene glycol–2‐amino‐5‐methylthio‐1,3,4‐thiadizole (PS–TEG–AMTZ)] were studied in detail. The results show that the adsorption kinetics of PS–DEG–AMTZ and PS–TEG–AMTZ for Hg²⁺ and Ag⁺ could be described by a pseudo‐second‐order rate equation. The introduction of a spacer arm between the polymeric matrix and functional group was beneficial for increasing the adsorption rates. The apparent activation energies of the resins for Hg²⁺ and Ag⁺ were within 20.89–32.32 kJ/mol. The Langmuir model could describe the isothermal process of Hg²⁺ and Ag⁺. The competitive adsorption of the resins for Hg²⁺ and Ag⁺ in binary mixture systems was also investigated. The results show that Hg²⁺ and Ag⁺ were adsorbed before the other metal ions, such as Cu²⁺, Zn²⁺, Fe³⁺, Cd²⁺, and Pb²⁺, under competitive conditions. Five adsorption–desorption cycles were conducted for the reuse of the resins. The results indicate that these two resins were suitable for reuse without considerable changes in the adsorption capacity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Poly[poly(oxypropylene) phosphate] macroionophores for transport and separation of cations in a hybrid: Cation‐exchange polymer and liquid membrane system

Poly[poly(oxypropylene) phosphate]s (PPOPP, M_n = 5800, 8100, 10,400), with different POP units (400, 1200, 2000), were synthesized and applied as cation‐selective macroionophores in a multimembrane hybrid system (MHS). The solution of PPOPP in dichloroethane formed the flowing liquid membrane (FLM) circulating between two polymer cation‐exchange membranes, and subsequently, between two polymer‐made pervaporation (PV) membranes. It was found that the PPOPP macroionophores activate the preferential transport of Zn²⁺ cations from aqueous solutions containing competing Cu²⁺, Ca²⁺, Mg²⁺, K⁺, and Na⁺ cations. The following separation orders were observed for PPOPPs with POP‐400 and POP‐1200: Zn²⁺ > Cu²⁺ ? Ca²⁺, Mg²⁺, K⁺, Na⁺, and for PPOPP with POP‐2000: Zn²⁺ > Cu²⁺,Ca²⁺ ? Mg²⁺, K⁺, Na⁺. Always, the particular cations are separated as: Zn²⁺ > Cu²⁺, Ca²⁺ > Mg²⁺, and K⁺ > Na⁺. The properties of PPOPPs were compared to respective transport and separation characteristics corresponding to those of respective poly(propylene glycol)s and poly(oxypropylene) bisphosphates. The results of investigation indicate that the bifunctional character of PPOPPs is caused by the presence of ionizable groups and probably pseudocyclic POP structures. By comparing the separation of cations in the simple MHS[FLM] system and the system supported by pervaporation unit [MHS[FLM‐PV] it was found that continuous dehydration of an organic FLM improves the system overall performance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1436–1445, 2004     

Water‐absorption characteristics of organic–inorganic composite superabsorbent polymers and its effect on summer maize root growth

Adding inorganic materials in SAPs to synthesize organic–inorganic composite superabsorbent polymers (OICSAPs) can effectively improve salt‐tolerance, gel strength, thermal stability, and water retention. However, most researches mainly focus on synthesizing process optimization and new multifunctional products, lacking reports on how ions affected water‐absorption characteristics and mechanism of OICSAPs and its influence on summer maize root growth. On the basis of these, we set up laboratory experiments and field cultivation experiment, using environmental scanning electron microscopy (ESEM) and fractal theory to study the questions above. Results show that OICSAPs have better salt‐tolerance, while cations and concentration affected its water‐absorption characteristics significantly. With higher cation valence, larger ionic radius, and concentration, its water‐absorption rate reduced remarkably as Na⁺ < K⁺ < Mg²⁺ < Ca²⁺ < Fe²⁺ < Fe³⁺ < Al³⁺ < Cu²⁺, while the effects of anions could be neglected. The OICSAPs presented typical honeycomb membrane‐like 3D crosslinked network structure, but Ca²⁺, Mg²⁺, Fe²⁺, Fe³⁺, Al³⁺, and Cu²⁺ would damage the structure (Cu²⁺ with the most significant effect) in local microdomain, and changed the complexity of pores. In the experiment, higher concentration could reduce water‐absorption rate without changing micromorphological characteristics. Applying OICSAPs will reduce total length, surface area, and volume of summer maize root, while promoting absorbing and transmitting ability by larger root diameter and the proportion of root <0.5 cm. All these results will provide a theoretical basis on application, marketing, and product development of OICSAPs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Photocatalytic Performance of Nitrogen‐Doped and Cu2+ and Ag+ Co‐Doped Sodium Trititanate

Nano‐sized (i) N‐doped sodium trititanate and (ii) N and Cu²⁺ (Ag⁺) co‐doped sodium trititanates CuTi₃NO_6?x (Ag₂Ti₃NO_6?x) were prepared by a solid‐state and ion‐exchange methods, respectively. The materials were characterized by EDS, PXRD, XPS, FESEM, TEM, UV–visible DRS, and Raman spectroscopy. All the materials were crystallized in monoclinic lattice with P21/m space group. The bandgap energy of all the samples was deduced from their UV–visible DRS profiles. Visible‐light‐induced photocatalytic oxidation of the methylene blue (MB) and methyl orange (MO), cyclohexene and phenol, was examined. The Ag⁺ co‐doped trititanate exhibited the highest photocatalytic activity among the materials investigated.     

Mg2+, Sr2+, Ag+, and Cu2+ co-doped β-tricalcium phosphate: Improved thermal stability and mechanical and biological properties

β-tricalcium phosphate (β-TCP, β-Ca₃(PO₄)₂) is an attractive biomaterial for bone repair applications. However, its sintering and mechanical properties are limited by a problematic phase transition to α-TCP. Cationic doping of β-TCP is able to postpone the formation of α-TCP allowing higher sintering temperatures and better mechanical properties. The co-doping of β-TCP with Mg²⁺ and Sr²⁺ has already been studied in detail, but the addition of antibacterial cations (Ag⁺ and Cu²⁺) on the Mg–Sr β-TCP co-doped composition remains unexplored. Thus, two co-doped β-TCP compositions were realized by aqueous precipitation technique without any secondary phase and compared with undoped β-TCP: Mg–Sr (2.0–2.0 mol%) and Mg–Sr–Ag–Cu (2.0–2.0–0.1–0.1 mol%). Differential thermal analysis and dilatometry analyses showed a slight decrease of the β-TCP → α-TCP phase transition temperature for the Mg–Sr–Ag–Cu (2.0–2.0–0.1–0.1% mol) composition as compared to the Mg–Sr (2.0–2.0 mol%). However, both exhibited much higher transition temperatures than undoped β-TCP. The addition of Ag⁺ and Cu²⁺ slightly reduces the grain size after sintering compared to the Mg–Sr (2.0–2.0 mol%) and the undoped compositions. The co-doped compositions also exhibited improved mechanical properties, specifically a higher Vickers hardness and elastic modulus. Finally, cell proliferation assays showed that the presence of dopants, even Ag⁺ and Cu²⁺, does not affect the survival and proliferation of cells. Thus, the use of Mg²⁺, Sr²⁺, Ag⁺, and Cu²⁺ co-doped β-TCP could be very promising for biomedical applications due to the improvements of these dopants on the thermal stability and mechanical and biological properties.