Search Results (13)

This study investigates the regeneration, reuse, stabilization, and environmental safety of Fe–Mn polymer nanocomposites for arsenic (As) removal and their environmental safety. The regeneration performance of Fe–Mn polymer nanocomposites (PS-FMBO) used in this study was assessed through batch adsorption–desorption cycles using various eluents, including NaOH, NaOH–NaCl, and NaOH–NaOCl mixtures. The results demonstrated that 0.1 M NaOH yielded the best regeneration performance, maintaining higher adsorption efficiency over multiple cycles. Stronger desorption agents caused a significant decline in removal efficiency due to possible structural degradation of the PS-FMBO nanocomposite, suggesting that aggressive desorption conditions could compromise its long-term effectiveness. The stabilization of PS-FMBO with cement and quicklime was evaluated for immobilizing As, iron (Fe), and manganese (Mn). Leaching tests indicated that the composites effectively immobilized these contaminants, with minimal leaching observed even after prolonged aging, ensuring compliance with environmental safety regulations. Furthermore, chitosan-based foams were analyzed for their chemical stability, with leaching tests confirming low concentrations of As, Fe, and Mn, even under aggressive conditions, further reinforcing the material’s safety and environmental compliance. These findings underscore the potential of PS-FMBO composites and chitosan-based foams as sustainable materials for hazardous waste management and eco-friendly construction applications. Their ability to immobilize contaminants while maintaining structural integrity highlights their practical significance in reducing environmental pollution and advancing circular economy principles. Full article

Herein, we report the methodological impact on the curing kinetics of bone cement based on polymer nanocomposites prepared using different methods. Poly (styrene-co-methylmethacrylate)–2D nanofiller nanocomposites (P(S-MMA)–2D Nanofiller) were prepared using bulk and suspension polymerization methods to study the effect of the different methods. The prepared nanocomposites were well-characterized for chemical, thermal, mechanical, and structural characteristics using Fourier Transform Infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), nano-indentation, and scanning electron microscopy (SEM) techniques, respectively. The FT-IR results confirmed the successful formation of the polymer nanocomposites. The DSC results showed that the prepared nanocomposites have higher thermal stabilities than their copolymer counterparts. The nano-indentation results revealed that the elastic modulus of the copolymer nanocomposites (bulk polymerization) was as high as 7.89 GPa, and the hardness was 0.219 GPa. Incorporating the 2D nanofiller in the copolymer matrix synergistically enhances the thermo-mechanical properties of the bone cement samples. The polymer nanocomposites prepared using the suspension polymerization method exhibit faster-curing kinetics (15 min) than those prepared using the bulk polymerization (120–240 min) method. Full article

This review summarizes the recent advancements in the mechanical properties of nanocomposites reinforced with surface-modified carbon nanotubes (CNTs). A range of matrices, namely, polymers, metals, and cement, is investigated, which have demonstrated increasing importance in a broad range of industrial sectors, such as 3D printing, automotive, construction, and coatings. The strengthening mechanisms that CNTs impart in composites are reviewed, and synergistic effects with their surface groups or co-additives are analyzed, including wettability, mechanical interlocking, and chemical bonding. Different mechanical and functional properties of the CNT-reinforced nanocomposites are analyzed, such as tensile strength, flexural strength, impact resistance, thermal conductivity, and electrical conductivity. The improvements in these properties for a variety of CNT-based composites are presented, and details on how these improvements were attained are discussed. The review concludes that surface modification of CNTs has proven to be of high importance, enhancing compatibility with various matrices and facilitating improvements in the nanocomposite properties. Suggestions for viable CNT-based composites for use in the studied applications are also provided. Full article

The success of composite materials is attributed to the nature of bonding at the nanoscale and the resulting structure-related properties. This study reports on the interaction, electronic, and optical properties of diamond nanothread/polymers (cellulose and epoxy) and boron nitride nanotube/calcium silicate hydrate composites using density functional theory modeling. Our findings indicate that the interaction between the nanothread and polymer is due to van der Waals-type bonding. Minor modifications in the electronic structures and absorption spectra are noticed. Conversely, the boron nitride nanotube–calcium silicate hydrate composite displays an electron-shared type of interaction. The electronic structure and optical absorption spectra of the diamond nanothread and boron nitride nanotube in all configurations studied in the aforementioned composite systems are well maintained. Our findings offer an electronic-level perspective into the bonding characteristics and electronic–optical properties of diamond nanothread/polymer and boron nitride nanotube/calcium silicate hydrate composites for developing next-generation materials. Full article

Polymer nanocomposites have recently been introduced as lead-free shielding materials for use in medical and industrial applications. In this work, novel shielding materials were developed using low-density polyethylene (LDPE) mixed with four different filler materials. These four materials are cement, cement with iron oxide, cement with aluminum oxide, and cement with bismuth oxide. Different weight percentages were used including 5%, 15%, and 50% of the cement filler with LDPE. Furthermore, different weight percentages of different combinations of the filler materials were used including 2.5%, 7.5%, and 25% (i.e., cement and iron oxide, cement and aluminum oxide, cement and bismuth oxide) with LDPE. Bismuth oxide was a nanocomposite, and the remaining oxides were micro-composites. Characterization included structural properties, physical features, mechanical and thermal properties, and radiation shielding efficiency for the prepared composites. The results show that a clear improvement in the shielding efficiency was observed when the filler materials were added to the LDPE. The best result out of all these composites was obtained for the composites of bismuth oxide (25 wt.%) cement (25 wt.%) and LDPE (50 wt.%) which have the lowest measured mean free path (MFP) compared with pure LDPE. The comparison shows that the average MFP obtained from the experiments for all the eight energies used in this work was six times lower than the one for pure LDPE, reaching up to twelve times lower for 60 keV energy. The best result among all developed composites was observed for the ones with bismuth oxide at the highest weight percent 25%, which can block up to 78% of an X-ray. Full article

Graphene, renowned for its exceptional mechanical, thermal, and electrical properties, is being explored as a cement nanofiller in the construction field. However, the limited water dispersibility of graphene requires the use of polymer superplasticizers, such as polycarboxylate ether (PCE). Previous studies have investigated the mechanisms by which PCE facilitates the dispersion of graphene within cement nanocomposites. However, such studies have made minimal progress, indicating a lack of understanding of the effect of residual PCE (rPCE) remaining in aqueous solution without binding to graphene. In this study, the effects of rPCE on the dispersion of graphene and the mechanical properties of graphene–cement composites (GCCs) were systematically analyzed. For this purpose, the content of rPCE was accurately measured through the centrifugation process and thermal analysis of graphene dispersion with PCE, and the result was 78.0 wt.% compared to graphene. The optical microscopy, particle size analysis, and contact angle measurement of the graphene dispersions with and without rPCE confirmed that rPCE is crucial for the dispersion of graphene and the enhancement of the interfacial affinity between graphene and cement. Additionally, the compressive strength of GCC with rPCE exhibited a substantial enhancement of approximately 10% (68.36 MPa) compared to plain cement (62.33 MPa). The effectiveness of rPCE in enhancing compressive strength correlated with the uniform dispersion of graphene within GCC and the promotion of cement hydration, as evidenced by field emission scanning electron microscopy and X-ray diffraction, respectively. Full article

Shape memory and self-healing polymer nanocomposites have attracted considerable attention due to their modifiable properties and promising applications. The incorporation of nanomaterials (polypyrrole, carboxyl methyl cellulose, carbon nanotubes, titania nanotubes, graphene, graphene oxide, mesoporous silica) into these polymers has significantly enhanced their performance, opening up new avenues for diverse applications. The self-healing capability in polymer nanocomposites depends on several factors, including heat, quadruple hydrogen bonding, π–π stacking, Diels–Alder reactions, and metal–ligand coordination, which collectively govern the interactions within the composite materials. Among possible interactions, only quadruple hydrogen bonding between composite constituents has been shown to be effective in facilitating self-healing at approximately room temperature. Conversely, thermo-responsive self-healing and shape memory polymer nanocomposites require elevated temperatures to initiate the healing and recovery processes. Thermo-responsive (TRSMPs), light-actuated, magnetically actuated, and Electrically actuated Shape Memory Polymer Nanocomposite are discussed. This paper provides a comprehensive overview of the different types of interactions involved in SMP and SHP nanocomposites and examines their behavior at both room temperature and elevated temperature conditions, along with their biomedical applications. Among many applications of SMPs, special attention has been given to biomedical (drug delivery, orthodontics, tissue engineering, orthopedics, endovascular surgery), aerospace (hinges, space deployable structures, morphing aircrafts), textile (breathable fabrics, reinforced fabrics, self-healing electromagnetic interference shielding fabrics), sensor, electrical (triboelectric nanogenerators, information energy storage devices), electronic, paint and self-healing coating, and construction material (polymer cement composites) applications. Full article

Carbon nanotubes (CNTs), known for their exceptional mechanical, thermal, and electrical properties, are being explored as cement nanofillers in the construction field. However, due to the limited water dispersion of CNTs, polymer dispersing agents like polycarboxylate ether (PCE) and sulfonated naphthalene formaldehyde (SNF) are essential for uniform dispersion. In a previous study, PCE and SNF, common cement superplasticizers, effectively dispersed CNTs in cement nanocomposites. However, uncertainties remained regarding the extent to which all dispersing agents interacted efficiently with CNTs. Therefore, this research quantitatively assessed CNT interaction with dispersing agents through dispersion and centrifugation. Approximately 37% of PCE and 50% of SNF persisted compared to CNT after centrifugation. The resulting cement nanocomposites, with optimized mixing ratios, exhibited enhanced compressive strength of about 14% for CNT/PCE (78.13 MPa) and 12.3% for CNT/SNF (76.97 MPa) compared to plain cement (68.52 MPa). XRD results linked strength reinforcement to increased cement hydrate from optimized CNT dispersion. FE-SEM analysis revealed that CNTs were positioned within the pores of the cement. These optimized cement nanocomposites hold promise for improved safety in the construction industry. Full article

A novel series of biodegradable polylactide-based triblock polyurethane (TBPU) copolymers covering a wide range of molecular weights and compositions were synthesized for potential use in biomedical applications. This new class of copolymers showed tailored mechanical properties, improved degradation rates, and enhanced cell attachment potential compared to polylactide homopolymer. Triblock copolymers, (TB) PL-PEG-PL, of different compositions were first synthesized from lactide and polyethylene glycol (PEG) via ring-opening polymerization in the presence of tin octoate as the catalyst. After which, polycaprolactone diol (PCL-diol) reacted with TB copolymers using 1,4-butane diisocyanate (BDI) as a nontoxic chain extender to form the final TBPUs. The final composition, molecular weight, thermal properties, hydrophilicity, and biodegradation rates of the obtained TB copolymers, and the corresponding TBPUs were characterized using ¹H-NMR, GPC, FTIR, DSC, and SEM, and contact angle measurements. Results obtained from the lower molecular weight series of TBPUs demonstrated potential use in drug delivery and imaging contrast agents due to their high hydrophilicity and degradation rates. On the other hand, the higher molecular weight series of TBPUs exhibited improved hydrophilicity and degradation rates compared to PL-homopolymer. Moreover, they displayed improved tailored mechanical properties suitable for utilization as bone cement, or in regeneration medicinal applications of cartilage, trabecular, and cancellous bone implants. Furthermore, the polymer nanocomposites obtained by reinforcing the TBPU3 matrix with 7% (w/w) bacterial cellulose nanowhiskers (BCNW) displayed a ~16% increase in tensile strength, and 330% in % elongation compared with PL-homo polymer. Full article

Acrylic polymer/cement nanocomposites in dark and light colors have been developed for coating floors and swimming pools. This work aims to emphasize the effect of cement filling on the mechanical parameters, thermal stability, and wettability of acrylic polymer. The preparation was carried out using the casting method from acrylic polymer coating solution, which was added to cement nanoparticles (65 nm) with weight concentrations of (0, 1, 2, 4, and 8 wt%) to achieve high-quality specifications and good adhesion. Maximum impact strength and Hardness shore A were observed at cement ratios of 2 wt% and 4 wt%, respectively. Changing the filling ratio has a significant effect on the strain of the nanocomposites. The contact angle was increased as the concentration of additives and cement increased, indicating that the synthesized coating is not hydrophilic and does not allow water permeability through it. The results show that the acrylic polymer/cement with a cement ratio of 8 wt% is the best nanocomposite for high-efficiency waterproofing. Full article

Hybrid nanocomposite hydrogels, as admixtures for internal curing of cementitious materials, have been widely studied. This study analyzes the effect of applying 0.5% (wt/wt cement) of pre-soaked hydrogels based on polyacrylamide, carboxymethylcellulose, and three different concentrations of Cloisite-Na⁺ (0, 10, and 20% wt/wt) on the fresh and hardened properties of cementitious mortars. In general, all mortars with hydrogel decreased the consistency index, mainly M20, due to the high concentration of Cloisite-Na⁺ that modifies the release kinect of the hydrogel. The results showed a slight variation, with an overall average value of 99% water retention in all mortars. This behavior is due to the portion of hydrogel-mortars dosage water retained to reduce the availability of free water in the mixture because this amount of water is stored, a priori, within the polymer particles. At 28 d, the mortars produced with hydrogels containing 20% of nanoclay (M20) exhibit mechanical behavior similar to the reference mortar (M), which corroborates the percentage of voids found. Scanning electron microscope images confirm that the M and M20 mortars are uniform and possess few pores or microcracks. Thus, these hybrid hydrogels have the potential to be innovative materials for water control improvements in cementitious materials technology. Full article

With the continuous research efforts, sophisticated predictive molecular dynamics (MD) models for C-S-H have been developed, and the application of MD simulation has been expanded from fundamental understanding of C-S-H to nano-engineered cement composites. This paper comprehensively reviewed the current state of MD simulation on calcium-silicate-hydrate (C-S-H) and its diverse applications to nano-engineered cement composites, including carbon-based nanomaterials (i.e., carbon nanotube, graphene, graphene oxide), reinforced cement, cement–polymer nanocomposites (with an application on 3D printing concrete), and chemical additives for improving environmental resistance. In conclusion, the MD method could not only compute but also visualize the nanoscale behaviors of cement hydrates and other ingredients in the cement matrix; thus, fundamental properties of C-S-H structure and its interaction with nanoparticles can be well understood. As a result, the MD enabled us to identify and evaluate the performance of new advanced nano-engineered cement composites. Full article

Bioactive dimethacrylate composites filled with silver nanoparticles (AgNP) might be used in medical applications, such as dental restorations and bone cements. The composition of bisphenol A glycerolate dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) mixed in a 60/40 wt% ratio was filled from 25 to 5000 ppm of AgNP. An exponential increase in resin viscosity was observed with an increase in AgNP concentration. Curing was performed by way of photopolymerization, room temperature polymerization, and thermal polymerization. The results showed that the polymerization mode determines the degree of conversion (DC), which governs the ultimate mechanical properties of nanocomposites. Thermal polymerization resulted in a higher DC than photo- and room temperature polymerizations. The DC always decreased as AgNP content increased. Flexural strength, flexural modulus, hardness, and impact strength initially increased, as AgNP concentration increased, and then decreased at higher AgNP loadings. This turning point usually occurred when the DC dropped below 65% and moved toward higher AgNP concentrations, according to the following order of polymerization methods: photopolymerization < room temperature polymerization < thermal polymerization. Water sorption (WS) was also determined. Nanocomposites revealed an average decrease of 16% in WS with respect to the neat polymer. AgNP concentration did not significantly affect WS. Full article