Synthesis and properties of waterborne epoxy acrylate nanocomposite coating modified by MAP-POSS

In this paper, waterborne epoxy acrylate (EA) coating modified with methylacryloylpropyl polyhedral oligomeric silsesquioxanes (MAP-POSS) was prepared. The cure kinetics of the coating was investigated by differential scanning calorimetry (DSC). The curing process, thermal and mechanical properties of the coating were investigated by FTIR, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). These results show that the non-isothermal curing process can be described by Kissinger method and a two-parameter autocatalytic Šesták–Berggren (S–B) model. The kinetic equations of curing reaction were obtained. The UV-curing property of MAP-POSS/EA nanocomposite coating is better than that of pure epoxy acrylate system. The glass transition temperature (T_g) increases with increasing MAP-POSS content. When MAP-POSS content is 12 wt%, the T_g reaches the maximum 54.3 °C which is 9.5 °C higher than that of pure epoxy acrylate.     

The use of nanoclay in preparation of epoxy anticorrosive coatings

Epoxy/clay nanocomposites (NC) have become a very interesting topic among researchers in the past two decades because nanoclays have a positive effect on the mechanical, thermal and especially barrier and anticorrosive performances of the polymers. In this study epoxy NCs and NC-based epoxy coatings were prepared by the solution intercalation method using Cloisite 30B as nanoclay. WAXD and SEM analyses revealed that a mainly exfoliated structure was obtained in epoxy NC with 1 wt% clay content, while higher clay loadings reduced the number of exfoliated clay nanolayers and produced a mainly intercalated structure. EIS, TGA and DMA analyses showed that epoxy NCs with clay content below 5 wt% exhibited increased corrosion stability, thermal stability, glass transition temperature (T_g) and storage modulus (G′), in both glassy and rubbery states due to the nanoscale dispersion of Cloisite 30B and the barrier effect of individual nanolayers. Enhanced mechanical properties were also noticed at higher clay loadings, but the rate of improvement was lower. The highest extent of exfoliation and the most homogeneous macromolecular network was found for NC with 1 wt% of clay, leading to the highest improvement of thermal and anticorrosive properties. The salt spray test results showed that anticorrosive properties of epoxy coatings in the presence of 3 wt% and especially 1 wt% of Cloisite 30B were significantly better, thus indicating that nanoclay efficiently modifies the commercial epoxy coatings.     

Morphology and thermal properties of inorganic-organic hybrids involving epoxy resin and polyhedral oligomeric silsesquioxanes

The organic-inorganic hybrids involving epoxy resin and polyhedral oligomeric silsesquioxanes (POSS) were prepared via in situ polymerization of diglycidyl ether of bisphenol A (DGEBA) and 4,4′-diaminodiphenylmethane (DDM) in the presence of the two structurally similar POSS monomers. The organic groups on silsesquioxane cage are aminophenyl and nitrophenyl groups, respectively. The curing reactions were started from the initially homogeneous mixture of DGEBA, DDM and the POSS cages. The inorganic-organic hybrids containing up to 20 wt% of POSS were obtained. The morphologies of the resulting hybrids were quite dependent on the types of R groups in the POSS monomers. The phase separation induced by polymerization occurred in the hybrids containing octanitrophenyl POSS (OnpPOSS) and the spherical particles of POSS-rich phase (<0.5 μm in diameter) were uniformly dispersed the continuous epoxy matrix as shown by scanning electronic microscopy. In marked contrast to the OnpPOSS-containing hybrids, the octaaminophenyl POSS (OapPOSS)-containing nanocomposites exhibited a homogeneous morphology. Differential scanning calorimetry and dynamic mechanical analysis showed that the glass transition temperatures (T_g) of the POSS-containing hybrids were lower than that of the control epoxy. The moduli of glass states for the hybrids are significantly higher than that of the control epoxy. For the OapPOSS epoxy nanocomposites the storage moduli of the rubbery plateau were higher than that of the control epoxy when the contents of POSS are less than 20 wt%, indicating the nanoreinforcement effect of POSS cages. Thermogravimetric analysis indicates that the thermal stability of the polymer matrix was not much sacrificed by introducing a small amount of POSS, whereas the properties of oxidation resistance of the materials were significantly enhanced. The OapPOSS epoxy nanocomposites displayed more pronounced improvement than the OnpPOSS hybrids, which could be ascribed to the nanoscaled dispersion of POSS cages and the formation of tether structure of POSS cages with epoxy matrix.     

Preparation, characterization and mechanical properties of epoxidized soybean oil/clay nanocomposites

New epoxidized soybean oil (ESO)/clay nanocomposites have been prepared with triethylenetetramine (TETA) as a curing agent. The dispersion of the clay layers is investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM data reveal the intercalated structure of ESO/clay nanocomposites has been developed. The thermogravimetric analysis exhibits that the ESO/clay nanocomposites are thermally stable at temperatures lower than 180 °C, with the maximum weight loss rate after 325 °C. The glass transition temperature, T_g, about 7.5 °C measured by differential scanning calorimetry (DSC) and T_g about 20 °C measured by dynamic mechanical study have been obtained. The difference in the T_g between DSC and dynamic measurements may be caused by different heating rate. The nanocomposites with 5-10 wt% clay content possess storage modulus ranging from 2.0×10⁶ to 2.70×10⁶ Pa at 30 °C. The Young's modulus (E) of these materials varies from 1.20 to 3.64 MPa with clay content ranging from 0 to 10 wt%. The ratio of epoxy (ESO) to hydrogen (amino group of TETA) greatly affects dynamic and tensile mechanical properties. At higher amount of TETA, the nanocomposites exhibit stronger tensile and dynamic properties.     

Preparation and properties of LDHs/epoxy nanocomposites

Layered double hydroxides (LDHs)/epoxy nanocomposites were prepared by mixing the amino laurate intercalated LDHs, EPON 828 resin, and Jeffamine D400 as a curing agent. The organo-modified LDHs with hydrophobic property easily disperse in epoxy resin, and the amino laurate intercalated LDHs with large gallery space allow the epoxy molecules and the curing agents to easily diffuse into the LDHs galleries at elevated temperature. After the thermal curing process, the exfoliated LDHs/epoxy nanocomposites were formed. X-ray diffraction was used to detect the formation process of the exfoliated LDHs/epoxy nanocomposites. TEM was used to observe the dispersed behavior of the LDHs nanolayers, and the LDHs nanolayers were exfoliated and well dispersed in these nanocomposites. Owing to the reaction between the amine groups of the intercalated amino laurate and epoxy groups, the adhesion between the LDHs nanolayers and epoxy molecules makes these LDHs/epoxy nanocomposites more compatible. Consequently, the tensile properties from tensile test and the mechanical properties from DMA were enhanced, and the T_g of these nanocomposites from DMA and TMA were increased. Coefficients of thermal expansion (CTEs, below and above T_g) of these nanocomposites from TMA decreased with the LDHs content. The thermal stability of these nanocomposites was enhanced by the well dispersed LDHs nanolayers.     

A study on the anticorrosion performance of the epoxy-polyamide nanocomposites containing ZnO nanoparticles

Epoxy nanocomposites were prepared using different loadings (2, 3.5, 5 and 6.5 wt%) of ZnO nanoparticles. Nanocomposites were applied on steel substrates. Samples were immersed in 3.5 wt% NaCl solution for 1344 h. Corrosion resistance of the coatings was studied by an electrochemical impedance spectroscopy (EIS). The effects of addition of nanoparticles on the mechanical properties of the epoxy coating were studied by a dynamic mechanical thermal analysis (DMTA). Curing behavior of the coatings containing nanoparticles was studied by a differential scanning calorimeter (DSC). Atomic force microscope (AFM) was utilized to investigate the surface topography and surface morphology of the coatings. Coating resistance against hydrolytic degradation was studied by FTIR (Fourier Transform Infrared).Results showed that addition of low loadings of nanoparticles can increase T_g of the composite. Decrease in T_g and cross-linking density of the coating were observed at high loadings of nanoparticles. It was found that nanoparticles can influence the curing behavior of the epoxy coating. Nanoparticles improved the corrosion resistance of the epoxy coating. Increase in coating resistance against hydrolytic degradation was obtained using nanoparticles.     

Intercalation and exfoliation behavior of epoxy resin/curing agent/montmorillonite nanocomposite

The epoxy resin/curing agent/montmorillonite nanocomposite was prepared by a casting and curing process. The intercalation and exfoliation behaviors of epoxy resin in the presence of organophilic montmorillonite were investigated by X‐ray diffraction (XRD) and dynamic mechanical thermal analysis (DMTA). For the diethylenetriamine curing agent, the intercalated nanocomposite was obtained; and the exfoliated nanocomposite would be formed for tung oil anhydride curing agent. The curing condition does not affect the resulting kind of composite, both intercalation or exfoliation. For intercalated nanocomposite, the glass transition temperature T_g, measured by DMTA and affected by the curing temperature of matrix epoxy resin is corresponded to that of epoxy resin without a gallery. The α′ peak of the loss tangent will disappear if adding montmorillonite into the composite. It was also found that the T_g of the exfoliated nanocomposite decreases with increasing montmorillonite loading. © 2002 John Wiley & Sons, Inc. J Appl Polym Sci 84: 842–849, 2002; DOI 10.1002/app.10354     

Montmorillonite intercalated by ammonium of octaaminopropyl polyhedral oligomeric silsesquioxane and its nanocomposites with epoxy resin

The octaammonium chloride salt of octaaminopropyl polyhedral oligomeric silsesquioxane (OapPOSS) was synthesized via the hydrolytic condensation of γ-aminopropyltrimethoxysilane in the methanol solution catalyzed by concentrated hydrochloric acid and was further used as the intercalating agent to modify sodium montmorillonite (MMT). X-ray diffraction (XRD) data indicate that the MMT was successfully intercalated by the ammonium of OapPOSS, as evidenced by the fact that the basal spacing of MMT galleries was expanded from 1.3 to 1.7 nm. The intercalation method used here introduced only the octaammonium POSS salt in contrast to the introduction of all hydrolyzed products from γ-aminopropyltriethoxysilane (APTEOS). The POSS-modified MMT was exploited to prepare the epoxy-MMT nanocomposites. Using a two-step technique, the disorderly exfoliated epoxy-MMT nanocomposites were obtained. XRD studies showed that the formation of the nanocomposites in all the cases with the disappearance of the peaks corresponding to the basal spacing of MMT. Transmission electronic microscopy (TEM) was used to investigate the morphology of the nanocomposites and indicates that the nanocomposites are comprised of a random dispersion of intercalated/exfoliated aggregates throughout the matrix. Differential scanning calorimetry (DSC) indicates that the glass transition temperatures of the as-prepared epoxy-MMT nanocomposites remained invariant in comparison with that of the control epoxy when the POSS-MMT content is less than 10 wt%. However, the nanocomposite containing 15 wt% of POSS-MMT displayed a decreased T_g, which could be attributed to the incomplete curing reaction resulting from the POSS-MMT loading. Thermogravimetric analysis (TGA) shows that the incorporation of POSS-MMT into epoxy networks displayed an apparent improvement in the thermal stability, and the char residue increased with increasing the concentration of POSS-MMT.     

Epoxy nanocomposites with octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane

The POSS-containing nanocomposites of epoxy resin were prepared via the co-curing reaction between octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) and the precursors of epoxy resin. The curing reactions were started from the initially homogeneous ternary solution of diglycidyl ether of bisphenol A (DGEBA), 4,4′-Diaminodiphenylmethane (DDM) and OpePOSS. The nanocomposites containing up to 40 wt% of POSS were obtained. The homogeneous dispersion of POSS cages in the epoxy matrices was evidenced by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and atomic force microscopy (AFM). Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) showed that at the lower POSS concentrations (<30 wt%) the glass transition temperatures (T_gs) of the nanocomposites almost remained invariant whereas the nanocomposites containing POSS more than 40 wt% displayed the lower T_gs than the control epoxy. The DMA results show that the moduli of the nanocomposites in glass and rubbery states are significantly higher than those of the control epoxy, indicating the nanoreinforcement effect of POSS cages. Thermogravimetric analysis (TGA) indicates that the thermal stability of the polymer matrix was not sacrificed by introducing a small amount of POSS, whereas the properties of oxidation resistance of the materials were significantly enhanced. The improved thermal stability could be ascribed to the nanoscaled dispersion of POSS cages and the formation of tether structure of POSS cages with epoxy matrix.     

Synthesis of novel bisphenol containing phthalazinone and azomethine moieties and thermal properties of cured diamine/bisphenol/DGEBA polymers

A novel bisphenol(1,2-dihydro-2-(4-((4-hydroxy)phenyliminomethylidene)phenyl)-4-(4-((4-(4-hydroxy)phenyliminomethylidene)phenoxy)phenyl)(2H)phthalazin-1-one, DPP) and a diamine(1,2-dihydro-2-(4-aminophenyl)-4-(4-(4-aminophenoxy)phenyl)(2H)phthalazin-1-one, DAP) were synthesized and characterized. The novel epoxy polymers containing phthalazinone and/or azomethine moieties were prepared by binary polymerization of DAP (or DPP) with diglycidyl ether of biphenyl A (DGEBA) and ternary polymerization of hybrid curing agents, DAP/DPP (DAP and DPP under different molar ratios) with DGEBA. The cure behaviors of these new epoxy systems were studied by dynamic differential scanning calorimeter (DSC) and Infrared (IR) scans. Especially, the activation energy of DAP/DGEBA calculated by Kissinger and Ozawa methods were 73.8 and 77.4 kJ/mol, respectively. For ternary epoxy system, it was found that hybrid curing agents of DAP/DPP exhibited significant associated effect on their reactivity towards the oxirane group. Glass transition temperatures (T_g's) of these new epoxy polymers were all above 150 °C from the results of DSC, and the initial thermal decomposition temperatures (T_d,5%'s) and integral procedure decomposition temperatures (IPDT's) of these new epoxy polymers are above 350 and 850 °C, respectively from results of thermogravimetric analyses (TGA). These results show that new epoxy polymers containing phthalazinone and/or azomethine moieties exhibited excellent thermal properties. Especially, thermal properties of the ternary epoxy polymers could be modified by changing the content of DAP and DPP. The linear relationships between char yield (Y_c,wt%) and the structural compositions of these new polymers (weight percentage of phthalazinone, azomethine and nitrogen, C/H weight ratio) were built.     

Structure and thermo-mechanical properties study of polyurethane-urea/glycidoxypropyltrimethoxysilane hybrid coatings

A series of organic–inorganic hybrid coatings were prepared using polyurethane (PU)-urea and glycidoxypropyltrimethoxysilane (GPTMS) To prepare this first acid terminated saturated polyester, having 230 hydroxyl value and acid value 25 mg/KOH, were reacted with coupling agent GPTMS at different concentrations in the presence of base catalyst and each of them were further reacted with isophorone diisocyanate (IPDI) at NCO/OH ratio of 1.6:1 for 4–5 h at 70–80 °C These prepolymers were casted on tin foil and cured at ambient conditions for 6 h and prepared the hybrid coating free films by amalgamation. These free films were stored in the room temperature for 40 days and used for further characterization. The coating without and with different concentrations of GPTMS were named as base polymer and hybrid coatings, respectively. FTIR spectroscopy was used for the structural analysis of the coatings. Thermogravimetric analysis (TGA) showed that thermal stability of the hybrids was significantly higher than the base polymer. The onset degradation temperature of the base polymer starts at 268.9 °C, while it ranges from 279.1 °C to 290.8 °C for the hybrids based on the concentration of GPTMS used. The glass transition temperature (T_g) and storage modulus as determined from DMTA were higher for hybrid coatings as compared to base polymer. T_g of base polymer was 42.3 °C while it varies between 65.8 °C to 83.5 °C for hybrids.     

Synthesis, characterization and properties of tetramethyl stilbene-based epoxy resins for electronic encapsulation

Two novel tetramethyl stilbene-based novolac (II and IV) were synthesized from 2,6-dimethyl phenol and chloroacetaldehyde dimethylacetal or chloroacetone, and then the resulted novolacs were epoxidized to tetramethyl stilbene-based epoxy resins (III and V). The proposed structures were confirmed by FTIR, elemental analysis, mass spectra, NMR spectra and epoxy equivalent weight titration. The synthesized tetramethyl stilbene-based epoxy resins were cured with 4,4-diaminodiphenyl methane (DDM) and 4,4-diaminodiphenyl sulfone (DDS). Thermal properties of cured epoxy resins were studied using dynamic mechanical analyzer, differential scanning calorimeter, thermal expansion analyzer and thermal gravimetric analyzer (TGA). These data were compared with that of the commercial tetramethyl biphenol (TMBP) epoxy system. According to the experimental data, the order of T_g for cured epoxy system is III>TMBP>V. The order of moisture absorption for cured epoxy system is V<III<TMBP. According to TGA, the 5% degradation temperatures in nitrogen atmosphere were in the range 370-377 and 397-412 °C for DDM and DDS curing systems, respectively. In air atmosphere, the 5% degradation temperatures were in the range 372-385 and 410-411 °C for DDM and DDS curing systems, respectively. The CTE is in inverse order with T_g, therefore, III/DDS<TMBP/DDS<V/DDS.     

Study on the preparation and characterization of biodegradable polylactide/multi-walled carbon nanotubes nanocomposites

In this study, polylactide/multi-walled carbon nanotubes (PLA/MWNTs) hybrids were prepared by means of a melt blending method. To enhance the compatibility between PLA and MWNTs, the acrylic acid grafted polylactide (PLA-g-AA) and the multihydroxyl-functionalized MWNTs (MWNTs-OH) were used to replace PLA and MWNTs, respectively. The crude MWNTs were chemically oxidized by a mixture of H₂SO₄ and HNO₃ and then reacted with thionyl chloride to functionalize them with chlorocarbonyl groups (MWNTs-COCl). The MWNTs-OH was finally obtained by the reaction of MWNTs-COCl and 1,6-hexanediol. The resulting products have been characterized by FTIR, ¹³C solid-state NMR, TGA, DMA, SEM, TEM, and Instron mechanical tester. Due to the formation of ester groups through the reaction between carboxylic acid groups of PLA-g-AA and hydroxyl groups of MWNTs-OH, results demonstrated dramatic enhancement in thermal and mechanical properties of PLA, for example, 77 °C increase in initial decomposition temperature with the addition of only 1 wt%. Based on the result of thermal and mechanical examinations, it was found that the optimal amount of MWNTs-OH was 1 wt% because excess MWNTs-OH caused separation of the organic and inorganic phases and lowered their compatibility.     

Maleimido-functionalized spirobislactone having enhanced volumetric expansion on polymerization

An approach to enhancing the volumetric expansion on polymerization of spirobislactone is proposed. This approach suggests a molecular modification of spirobislactone through attaching a rigid pendant segment bearing maleimido group to its aromatic ring. An additional volumetric expansion is achieved from loose molecular packing in cured resins due to the steric hindrance effect among rigid pendent segments. Thus a new monomer, maleimido-functionalized spirobislactone (MFS), is prepared. In order to evaluate the volumetric expansion of MFS during curing, tetraglycidyl 4,4′-diamino diphenyl methane (TGDDM) is employed to cure with MFS. The volumetric expansion of MFS on curing is measured to be 12.3%, higher than that of net spirobislactone monomer. The existence of loose molecular packing in MFS/epoxy cured resins is demonstrated by morphology observation of the cured resin stained by the phosphotungstic acid (PTA), and the stained regions are observed to be nanoparticles. Such a cured resin, prepared from 20 mol% of MFS and 80 mol% of TGDDM epoxy resin, shows excellent toughness (Charpy impact strength 13,000 J/m²) and good mechanical strength (flexural strength 120 MPa, storage flexural modulus 4.2 GPa). Its glass transition temperature by dynamic mechanical thermal analysis (DMA) attains 227 °C, much higher than that of the cured resin from net spirobislactone and epoxy resin.     

Novel organic-inorganic hybrids prepared from polybenzoxazine and titania using sol-gel process

Novel organic-inorganic hybrids were prepared from polybenzoxazine and titania using sol-gel process by blending titanium isopropoxide as a precursor for titania with a typical benzoxazine monomer, bis(3-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl)isopropane (Ba). Deep red brown and transparent hybrid materials were obtained after thermal cure at 200 °C. DSC indicated that, in the presence of titania precursor, the onset and maximum temperature of the exothermic peak due to the ring opening polymerization of Ba decreased by ca. 30 and 70 °C, respectively. Viscoelastic analyses revealed that the glass transition temperatures (T_g) of the polybenzoxazine-titania hybrids shifted to higher temperature than the neat polybenzoxazine. The storage moduli below T_g for the hybrids increased with the increase of the titania content, and the storage moduli were maintained constant up to higher temperature than the neat resin. TGA results confirmed that the thermal stability and char yield of polybenzoxazine increased by hybridization with titania.     

Preparation of epoxy resin/silica hybrid composites for epoxy molding compounds

Phenolic novolac/silica and cresol novolac epoxy/silica hybrids were prepared through in situ sol‐gel reaction of tetraethoxysilane (TEOS). The formed hybrids were utilized as a curing agent and an epoxy resin in epoxy curing compositions, respectively. Via the two‐step preparation route, the resulting epoxy resin/silica hybrid nanocomposites exhibited good thermal stability, high glass transition temperatures, and low coefficients of thermal expansion. High condensation degree of the condensed silica was observed with a high content of siloxane bridges, p > 85%, measured by ²⁹Si NMR. The two‐step route also provides feasibility of preparation of epoxy resin/silica hybrid nanocomposites compatible with the current processes of manufacturing of epoxy molding compounds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4047–4053, 2003     

Design,preparation and properties of novel renewable UV-curable copolymers based on cardanol and dimer fatty acids

A cardanol-based UV-curable vinyl ester (VE) monomer was prepared via simple esterification, and its successful synthesis was demonstrated by FTIR and ¹H-NMR. In order to improve its rigidity, it was mixed with certain proportions of another reactive bio-based VE monomer, maleic anhydride modified dimer fatty acids polymerized glycidyl methacrylate (MA-m-DA-p-GMA) which had rigid and strong polar groups, and then a series of UV-cured copolymers were prepared from the two VE monomers. The UV curing process was monitored by FTIR analysis. The tensile and thermal properties of the cured copolymer films were also investigated. UV curing analysis demonstrated that the double bonds in the mixed VE could be converted to ultimate curing level within 40 s. Tensile tests showed the prepared copolymers had a tensile strength of 8.86 MPa. Dynamic mechanical analysis (DMA) revealed the copolymers had relatively high glass transition temperature (T_g) from 40 to 60 °C. Thermogravimetric analysis (TGA) showed the copolymers containing higher content of CDMA had higher thermal stability, and all copolymers’ main thermal initial decomposition temperatures were above 410 °C, indicating the copolymers had certain thermal stability. These copolymer films can be used as eco-friendly materials in coatings and other applications to replace the currently used petroleum-based polymers.     

Study of fullerene-containing epoxy membranes with tunable ultraviolet light-filtering properties

Fullerene-containing epoxy membranes with tunable ultraviolet (UV) optical properties were prepared by adding various amounts of aminated-fullerene derivatives into an epoxy resin/ethylenediamine system. The influences of content and chemical structure (e.g., amine kind and addition degree) of aminated-fullerene on the mechanical, optical and thermal properties of the cured epoxy membranes were investigated systematically. Dynamic mechanical analysis (DMA) indicates that the aminated-fullerene participates in the epoxy curing process and that a star-like crosslinking structure is formed. A higher cross-link density results in a higher glass transition temperature and storage module. The UV–Vis absorbance spectra reveal that the cutoff wavelength λ_c of the aminated-fullerene/epoxy membranes can be changed over almost the entire UV region simply by varying the fullerene derivative content. The charge-transfer complexes formed between the fullerene derivatives and the epoxy-amine complex may be responsible for the UV light-filtering behaviors. The result of thermogravimertic analyses (TGA) reveals that a higher amount (0.48 wt%) of fullerene derivative obviously leads to the better thermal stability of the cured epoxy membrane.     

Layered double hydroxide-like materials: nanocomposites for use in concrete

Nitrobenzoic acid (NBA), naphthalene-2, 6-disulfonic acid (26NS), and naphthalene-2 sulfonic acid (2NS) salts were intercalated into a layered double hydroxide-like host material (LDH). The intercalation process was achieved by anion exchange of nitrates in the host material, Ca₂Al(OH)₆NO₃, nH₂O (CaAl LDH), which was prepared by a coprecipitation technique. The resulting organo derivatives CaAlNBA LDH, CaAl26NS LDH, and CaAl2NS LDH produced a tilted orientation of NBA and 26NS anions in the interlayer space, while 2NS anions induced a perpendicular bilayer arrangement.Materials characterization was carried out using X-ray diffraction (XRD), IR-spectroscopy, thermal analysis, and scanning electron microscopy (SEM). These preliminary results open up a new direction towards the synthesis of nanocomposites using polymeric entities and layered materials for future applications in cement and concrete science, e.g., control of the effect of admixtures on the kinetics of cement hydration by programming their temporal release.     

Side-chain phenol-functionalized poly(ether sulfone) and its contribution to high-performance and flexible epoxy thermosets

We prepared a side-chain phenol-functionalized poly(ether sulfone) (P1) from a one-pot reaction of a 4,4′-dihydroxybenzophenone (DHBP)-based poly(ether sulfone), poly(oxy-1,4-phenylenecarbonyl-1,4-phenyleneoxy-1,4-phenylene-sulfonyl-1,4-phenylene (DHBP-PES)), with 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and phenol in the presence of sulphuric acid. The phenol linkages of P1 act as reacting sites for epoxy resins. Subsequently, flexible and light-yellow transparent films of epoxy thermosets can be achieved from the curing of P1 with cresol novolac epoxy (CNE) and diglycidyl ether of bisphenol A (DGEBA). The thermoset based on P1 and CNE (P1/CNE) shows a high T_g value (241 °C), a low coefficient of thermal expansion (44 ppm/°C), and flame retardancy (VTM-0). The moderate-to-high molecular weight of P1 is responsible for the characteristics high T_g and flexibility, which are rarely seen in epoxy thermosets based on a low-molecular weight curing agent.