Synthesis and Application of Nanoparticles in Novel Composites

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Nanocomposite Materials".

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 24120

Special Issue Editors

School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019, USA
Interests: surfactants; admicellar polymerization; transport in biological systems; drug delivery; blood trauma
Department of Restorative Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA
Interests: dental biomaterials; antimicrobial; bioactive; biomimetic; nanoparticles; advanced characterizations (SEM, TEM, HIM, AFM, EDS, SAXS, SANS, and ToF-SIMS)

Special Issue Information

Dear Colleagues,

The utilization of nanoparticles/nanostructures to improve the properties of engineered materials is ubiquitous in many disciplines including chemistry, materials science, engineering, medicine, and dentistry. Their incorporation in the bulk or at the surface of a composite material provides an opportunity to impart desired properties. This peer-reviewed Special Issue, “Synthesis and Application of Nanoparticles in Novel Composites”, will provide an assessment of the most current approaches for the synthesis, incorporation, and functionalization of nanoparticles/nanostructures into novel materials with relevant antimicrobial, biomimetic, and mineralizing functionalities. Submitted manuscripts should pay special attention to the preparation, modification, and characterization of the nanoparticles/nanostructures of any composition and morphology, as well as the characterization of novel materials and their potential field/clinical applications.

  • Areas of interest include, but are not limited to, the following:
  • Nanoparticle synthesis
  • Nanoparticle surface modifications
  • Dental and medical biomaterials
  • Functionalized textiles 
  • Tissue engineering constructs
  • Cements modified with nanoparticles
  • Application of Janus nanoparticles in composites

Prof. Dr. Edgar O'Rear
Guest Editor

Dr. Fernando Esteban Florez
Guest Editor Assistant

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • nanoparticles (synthesis, modification, and functionalization)
  • nanostructures (nanotubes, nanowires, quantum dots, and nanosheets)
  • self-assembly
  • interfacial chemistry
  • composites
  • drug delivery
  • cements
  • biomaterials (polymer, ceramic, metallic, self-healing, stimuli-responsive, antibacterial, bioactive, and biomimetic)
  • tissue engineering (scaffolds, osteoinductive, osteoconductive, in vitro, animal models, and randomized clinical trials)

Published Papers (10 papers)

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Research

Jump to: Review

15 pages, 4473 KiB  
Article
Shear Bond Strength and Color Stability of Novel Antibacterial Nanofilled Dental Adhesive Resins
by Qing Hong, Alexandra C. Pierre-Bez, Matheus Kury, Mark E. Curtis, Rochelle D. Hiers, Fernando L. Esteban Florez and John C. Mitchell
Nanomaterials 2023, 13(1), 1; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13010001 - 20 Dec 2022
Cited by 5 | Viewed by 1669
Abstract
Experimental adhesives containing co-doped metaloxide nanoparticles were demonstrated to display strong and long-term antibacterial properties against Streptococcus mutans biofilms. The present study represents an effort to characterize the shear-bond strength (SBS) and color stability (CS) of these novel biomaterials. Experimental adhesives were obtained [...] Read more.
Experimental adhesives containing co-doped metaloxide nanoparticles were demonstrated to display strong and long-term antibacterial properties against Streptococcus mutans biofilms. The present study represents an effort to characterize the shear-bond strength (SBS) and color stability (CS) of these novel biomaterials. Experimental adhesives were obtained by dispersing nitrogen and fluorine co-doped titanium dioxide nanoparticles (NF_TiO2, 10%, 20% or 30%, v/v%) into OptiBond Solo Plus (OPTB). Dentin surfaces were wet-polished (600-Grit). Specimens (n = 5/group) of Tetric EvoCeram were fabricated and bonded using either OPTB or experimental (OPTB + NF_TiO2) adhesives. Specimens were stored in water (37 °C) for twenty-four hours (T1), three months (T2), and six months (T3). At T1, T2, or T3, specimens were removed from water storage and were tested for SBS. Disc-shaped specimens (n = 10/group; d = 6.0 mm, t = 0.5 mm) of adhesives investigated were fabricated and subjected to thermocycling (10,000 cycles, 5–55 °C, 15 s dwell time). Specimens’ colors were determined with a VITA Easyshade® V spectrophotometer (after every 1000 cycles). SBS data was analyzed using two-way ANOVA and post-hoc Tukey tests, while CS data was analyzed using one-way ANOVA and post-hoc Tukey tests (α = 0.05). Mean values of SBS ranged from 16.39 ± 4.20 MPa (OPTB + 30%NF_TiO2) to 19.11 ± 1.11 MPa (OPTB), from 12.99 ± 2.53 MPa (OPTB + 30% NF_TiO2) to 14.87 ± 2.02 (OPTB) and from 11.37 ± 1.89 (OPTB + 20% NF_TiO2) to 14.19 ± 2.24 (OPTB) after twenty-four hours, three months, and six months of water storage, respectively. Experimental materials had SBS values that were comparable (p > 0.05) to those from OPTB independently of nanoparticle concentration or time-point considered. Experimental materials with higher NF_TiO2 concentrations had less intense color variations and were more color stable than OPTB even after 10,000 thermocycles. In combination, the results reported have demonstrated that experimental adhesives can establish strong and durable bonds to human dentin while displaying colors that are more stable, thereby suggesting that the antibacterial nanotechnology investigated can withstand the harsh conditions within the oral cavity without compromising the esthetic component of dental restorations. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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17 pages, 4174 KiB  
Article
Characterization of Experimental Nanoparticulated Dental Adhesive Resins with Long-Term Antibacterial Properties
by Rochelle Denise Hiers, Pedro Huebner, Sharukh Soli Khajotia and Fernando Luis Esteban Florez
Nanomaterials 2022, 12(21), 3732; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12213732 - 24 Oct 2022
Cited by 5 | Viewed by 2307
Abstract
Experimental adhesives with functional nitrogen-doped titanium dioxide nanoparticles (N_TiO2) have been shown to display improved properties. However, these materials have not been characterized regarding their degree of conversion (DC), biaxial flexure strength (BFS), surface roughness (SR), elastic modulus (EM), and long-term [...] Read more.
Experimental adhesives with functional nitrogen-doped titanium dioxide nanoparticles (N_TiO2) have been shown to display improved properties. However, these materials have not been characterized regarding their degree of conversion (DC), biaxial flexure strength (BFS), surface roughness (SR), elastic modulus (EM), and long-term antibacterial functionalities. Experimental adhesives were synthesized by dispersing N_TiO2 (10%, 20%, or 30%, v/v%) into OptiBond Solo Plus (OPTB, Kerr Corp., USA). Unpolymerized adhesives (volume = 50 μL/drop, n = 3/group) were individually placed onto a heated (37 °C) attenuated total reflectance (ATR) monolithic diamond crystal (Golden Gate, Specac). The spectra of composites were obtained with a Fourier-transform infrared (FTIR) spectrometer (Nicolet IS50; 500–4500 cm−1; resolution = 4 cm−1, 10 internal scans/spectrum) before and after polymerization. Disk-shaped specimens (diameter = 6.0 mm, thickness = 0.5 mm) for BFS (n = 12/group), SR and EM (n = 3/group), and for antibacterial testing (n = 18/group/time-point) were fabricated and photopolymerized (1 min each; 385–515 nm, 1000 mW/cm2; VALO). DC values (%) were calculated from pre- and post-polymerization spectra using the two-frequency method and tangent-baseline technique. BFS was assessed using a universal testing machine (Instron 68TM-5, crosshead speed = 1.27 mm/min, 25 °C). SR and EM were investigated using an atomic force microscope (Multimode 8) with aluminum-coated silicon probes (8 nm pyramidal tip, spring constant 40 N/m, Bruker). Antibacterial testing was performed by growing Streptococcus mutans biofilms (UA159-ldh, 37 °C, microaerophilic) on the surfaces of specimens for 24 h and then measuring the relative luminescence units (RLU) with a Biotek Synergy HT multi-well plate reader. Results demonstrate that experimental materials containing 10%, 20%, and 30% of N_TiO2 displayed higher levels of DC, had better mechanical properties, and were able to exert strong and durable antibacterial properties without visible light irradiation and after extended periods of simulated shelf-life and aging in PBS. The reported experimental materials are expected to increase the service lives of polymer-based bonded restorations by decreasing the incidence of secondary caries. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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23 pages, 3290 KiB  
Article
Novel Experimental In-Office Bleaching Gels Containing Co-Doped Titanium Dioxide Nanoparticles
by Matheus Kury, Rochelle D. Hiers, Yan D. Zhao, Mayara Z. D. Picolo, Jessica Hsieh, Sharukh S. Khajotia, Fernando L. Esteban Florez and Vanessa Cavalli
Nanomaterials 2022, 12(17), 2995; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12172995 - 30 Aug 2022
Cited by 6 | Viewed by 2157
Abstract
The present study reports on the development and testing of novel bleaching agents containing co-doped metaloxide nanoparticles (NP; 0%, 5%, 10% v/w) and hydrogen peroxide (HP, 0%, 6%, 15%, and 35%). Bovine blocks (n = 200, A = 36 mm2) [...] Read more.
The present study reports on the development and testing of novel bleaching agents containing co-doped metaloxide nanoparticles (NP; 0%, 5%, 10% v/w) and hydrogen peroxide (HP, 0%, 6%, 15%, and 35%). Bovine blocks (n = 200, A = 36 mm2) were obtained and randomly distributed into experimental groups (n = 10/group). NPs were incorporated into gels before bleaching (3 sessions, 7 days apart, 30 min/session, irradiated with violet light-LT). Color changes (ΔE00, ΔWID), mineral content (CO32−, PO43−), and topography were assessed (spectrophotometer, ATR-FTIR, and AFM) before and after bleaching procedures (14 days). Metabolic status and three-dimensional components of non-disrupted Streptococcus mutans biofilms were investigated using a multimode reader and confocal microscopy. The results indicate that ΔE00 and ΔWID significantly increased with NPs’ concentrations and LT. The enamel’s mineral ratio was adversely impacted by HP, but alterations were less pronounced when using NP-containing gels. The enamel’s topography was not damaged by the bleaching protocols tested. The bioluminescence results show that bleaching protocols do not render latent antibacterial properties to enamel, and the confocal microscopy results demonstrate that the 3-dimensional distribution of the components was affected by the protocols. The proposed nanotechnology improved the bleaching efficacy of experimental materials independent of hydrogen peroxide or irradiation and did not adversely impact the enamel’s surface properties or its chemical content. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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17 pages, 3063 KiB  
Article
Strategy for Conjugating Oligopeptides to Mesoporous Silica Nanoparticles Using Diazirine-Based Heterobifunctional Linkers
by Md Arif Khan, Ramy W. Ghanim, Maelyn R. Kiser, Mahsa Moradipour, Dennis T. Rogers, John M. Littleton, Luke H. Bradley, Bert C. Lynn, Stephen E. Rankin and Barbara L. Knutson
Nanomaterials 2022, 12(4), 608; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12040608 - 11 Feb 2022
Cited by 5 | Viewed by 2625
Abstract
Successful strategies for the attachment of oligopeptides to mesoporous silica with pores large enough to load biomolecules should utilize the high surface area of pores to provide an accessible, protective environment. A two-step oligopeptide functionalization strategy is examined here using diazirine-based heterobifunctional linkers. [...] Read more.
Successful strategies for the attachment of oligopeptides to mesoporous silica with pores large enough to load biomolecules should utilize the high surface area of pores to provide an accessible, protective environment. A two-step oligopeptide functionalization strategy is examined here using diazirine-based heterobifunctional linkers. Mesoporous silica nanoparticles (MSNPs) with average pore diameter of ~8 nm and surface area of ~730 m2/g were synthesized and amine-functionalized. Tetrapeptides Gly-Gly-Gly-Gly (GGGG) and Arg-Ser-Ser-Val (RSSV), and a peptide comprised of four copies of RSSV (4RSSV), were covalently attached via their N-terminus to the amine groups on the particle surface by a heterobifunctional linker, sulfo-succinimidyl 6-(4,4′-azipentanamido)hexanoate (sulfo-NHS-LC-diazirine, or SNLD). SNLD consists of an amine-reactive NHS ester group and UV-activable diazirine group, providing precise control over the sequence of attachment steps. Attachment efficiency of RSSV was measured using fluorescein isothiocyanate (FITC)-tagged RSSV (RSSV-FITC). TGA analysis shows similar efficiency (0.29, 0.31 and 0.26 mol peptide/mol amine, respectively) for 4G, RSSV and 4RSSV, suggesting a generalizable method of peptide conjugation. The technique developed here for the conjugation of peptides to MSNPs provides for their attachment in pores and can be translated to selective peptide-based separation and concentration of therapeutics from aqueous process and waste streams. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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16 pages, 6731 KiB  
Article
Designing pH-Dependent Systems Based on Nanoscale Calcium Carbonate for the Delivery of an Antitumor Drug
by Victoriya Popova, Yuliya Poletaeva, Inna Pyshnaya, Dmitrii Pyshnyi and Elena Dmitrienko
Nanomaterials 2021, 11(11), 2794; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11112794 - 21 Oct 2021
Cited by 19 | Viewed by 2433
Abstract
Materials based on calcium carbonate (CaCO3) are widely used in biomedical research (e.g., as carriers of bioactive substances). The biocompatibility of CaCO3 and dependence of its stability on pH make these materials promising transporters of therapeutic agents to sites with [...] Read more.
Materials based on calcium carbonate (CaCO3) are widely used in biomedical research (e.g., as carriers of bioactive substances). The biocompatibility of CaCO3 and dependence of its stability on pH make these materials promising transporters of therapeutic agents to sites with low pH such as a tumor tissue. In this work, we developed an approach to the preparation of nanoscale particles based on CaCO3 (CaNPs) up to 200 nm in size by coprecipitation and analyzed the interaction of the nanoparticles with an anticancer drug: DOXorubicin (DOX). We also showed a prolonged pH-dependent release of DOX from a CaNP nanocarrier and effective inhibition of cancer cell growth by a CaCO3-and-DOX–based composite (CaNP7-DOX) in in vitro models. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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24 pages, 8339 KiB  
Article
Synthesis of Highly-Dispersed Graphene Oxide Nanoribbons–Functionalized Carbon Nanotubes–Graphene Oxide (GNFG) Complex and Its Application in Enhancing the Mechanical Properties of Cementitious Composites
by Peiqi Li, Junxing Liu, Sungwun Her, Erfan Zal Nezhad, Seungmin Lim and Sungchul Bae
Nanomaterials 2021, 11(7), 1669; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11071669 - 25 Jun 2021
Cited by 17 | Viewed by 2888
Abstract
In this study, a graphene oxide nanoribbons–functionalized carbon nanotubes–graphene oxide (GNFG) complex was hydrothermally synthesized as a nanomaterial for reinforcing cementitious composites, using a modified Hummers’ method. Three types of components existed in the GNFG: Type I, the functionalized carbon nanotubes–graphene oxide nanoribbons [...] Read more.
In this study, a graphene oxide nanoribbons–functionalized carbon nanotubes–graphene oxide (GNFG) complex was hydrothermally synthesized as a nanomaterial for reinforcing cementitious composites, using a modified Hummers’ method. Three types of components existed in the GNFG: Type I, the functionalized carbon nanotubes–graphene oxide nanoribbons (FCNTs–GNR); and types II and III are graphene oxide (GO) and functionalized carbon nanotubes (FCNTs), respectively, which exist independently. The dispersivity of GNFG and its effects on the mechanical properties, hydration process, and microstructures of cement pastes were evaluated, and the results were compared with those using cement pastes incorporating other typical carbon nanomaterials. The results demonstrated that dispersion of GNFG in aqueous solutions was superior to that of the CNTs, FCNTs, and GO/FCNTs mixture. Furthermore, the highly-dispersed GNFG (0.05 wt.%) improved the mechanical properties of the cement paste after 28 days of hydration and promoted the hydration of cement compared to CNTs, GO, and GO/FCNTs mixture (0.05 wt.%). The results in this study validated the feasibility of using GNFG with enhanced dispersion as a new nano-reinforcing agent for various cementitious systems. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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17 pages, 5759 KiB  
Article
PEGylated Gold Nanoparticles Grafted with N-Acetyl-L-Cysteine for Polymer Modification
by Dominik Fajstavr, Adéla Karasová, Alena Michalcová, Pavel Ulbrich, Nikola Slepičková Kasálková, Jakub Siegel, Václav Švorčík and Petr Slepička
Nanomaterials 2021, 11(6), 1434; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11061434 - 28 May 2021
Cited by 4 | Viewed by 2924
Abstract
The subjects of this work were the enhancement and determination of the stability and other properties of gold nanoparticles (AuNPs) in an aqueous solution, gold nanoparticle immobilization, and further surface grafting on polyethylene naphthalate (PEN). Gold nanoparticles in PEG with a subsequent water [...] Read more.
The subjects of this work were the enhancement and determination of the stability and other properties of gold nanoparticles (AuNPs) in an aqueous solution, gold nanoparticle immobilization, and further surface grafting on polyethylene naphthalate (PEN). Gold nanoparticles in PEG with a subsequent water solution addition were prepared using cathode sputtering; for the subsequent surface activation, two different solutions were used: (i) sodium citrate dihydrate (TCD) and (ii) N-acetyl-L-cysteine (NALC). The aim of this work was to study the effect of the concentration of these solutions on AuNPs stability, and further, the effect of the concentration of gold nanoparticles and their morphology, and to describe the aging process of solutions, namely, the optical properties of samples over 28 days. Stabilized AuNPs were prepared in an N-acetyl-L-cysteine (NALC) system and subsequently immobilized with NALC. The surface chemistry modification of AuNPs was confirmed using HRTEM/EDS. Gold nanoparticles were successfully immobilized with NALC. Grafting of the modified PEN from a solution of colloidal gold stabilized in the PEG–H2O–NALC system led to the polymer surface functionalization. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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15 pages, 2653 KiB  
Article
pH-Sensitive Chitosan Nanoparticles for Salivary Protein Delivery
by Yi Zhu, Lina M. Marin, Yizhi Xiao, Elizabeth R. Gillies and Walter L. Siqueira
Nanomaterials 2021, 11(4), 1028; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11041028 - 17 Apr 2021
Cited by 20 | Viewed by 3158
Abstract
Salivary proteins such as histatins (HTNs) have demonstrated critical biological functions directly related to tooth homeostasis and prevention of dental caries. However, HTNs are susceptible to the high proteolytic activities in the oral environment. Therefore, pH-sensitive chitosan nanoparticles (CNs) have been proposed as [...] Read more.
Salivary proteins such as histatins (HTNs) have demonstrated critical biological functions directly related to tooth homeostasis and prevention of dental caries. However, HTNs are susceptible to the high proteolytic activities in the oral environment. Therefore, pH-sensitive chitosan nanoparticles (CNs) have been proposed as potential carriers to protect proteins from enzymatic degradation at physiological salivary pH. Four different types of chitosan polymers were investigated and the optimal formulation had good batch to batch reproducibility, with an average hydrodynamic diameter of 144 ± 6 nm, a polydispersity index of 0.15 ± 0.04, and a zeta potential of 18 ± 4 mV at a final pH of 6.3. HTN3 encapsulation and release profiles were characterized by cationic polyacrylamide gel electrophoresis. The CNs successfully encapsulated HTN3 and selectively swelled at acidic pH to facilitate HTN3 release. Protection of HTN3 against enzymatic degradation was investigated in diluted whole saliva. HTN3 encapsulated in the CNs had a prolonged survival time compared to the free HTN3. CNs with and without HTN3 also successfully reduced biofilm weight and bacterial viability. The results of this study have demonstrated the suitability of CNs as potential protein carriers for oral applications, especially for complications occurring at acidic conditions. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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19 pages, 4246 KiB  
Article
Effect of Morphologically Controlled Hematite Nanoparticles on the Properties of Fly Ash Blended Cement
by Pantharee Kongsat, Sakprayut Sinthupinyo, Edgar A. O’Rear and Thirawudh Pongprayoon
Nanomaterials 2021, 11(4), 1003; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11041003 - 14 Apr 2021
Cited by 2 | Viewed by 1833
Abstract
Several types of hematite nanoparticles (α-Fe2O3) have been investigated for their effects on the structure and properties of fly ash (FA) blended cement. All synthesized nanoparticles were found to be of spherical shape, but of different particle sizes ranging [...] Read more.
Several types of hematite nanoparticles (α-Fe2O3) have been investigated for their effects on the structure and properties of fly ash (FA) blended cement. All synthesized nanoparticles were found to be of spherical shape, but of different particle sizes ranging from 10 to 195 nm depending on the surfactant used in their preparation. The cement hydration with time showed 1.0% α-Fe2O3 nanoparticles are effective accelerators for FA blended cement. Moreover, adding α-Fe2O3 nanoparticles in FA blended cement enhanced the compressive strength and workability of cement. Nanoparticle size and size distribution were important for optimal filling of various size of pores within the cement structure. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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Review

Jump to: Research

20 pages, 3654 KiB  
Review
Mechanical Strength and Conductivity of Cementitious Composites with Multiwalled Carbon Nanotubes: To Functionalize or Not?
by Edgar A. O’Rear, Suthisa Onthong and Thirawudh Pongprayoon
Nanomaterials 2024, 14(1), 80; https://0-doi-org.brum.beds.ac.uk/10.3390/nano14010080 - 27 Dec 2023
Viewed by 770
Abstract
The incorporation of carbon nanotubes into cementitious composites increases their compressive and flexural strength, as well as their electrical and thermal conductivity. Multiwalled carbon nanotubes (MWCNTs) covalently functionalized with hydroxyl and carboxyl moieties are thought to offer superior performance over bare nanotubes, based [...] Read more.
The incorporation of carbon nanotubes into cementitious composites increases their compressive and flexural strength, as well as their electrical and thermal conductivity. Multiwalled carbon nanotubes (MWCNTs) covalently functionalized with hydroxyl and carboxyl moieties are thought to offer superior performance over bare nanotubes, based on the chemistry of cement binder and nanotubes. Anionic carboxylate can bind to cationic calcium in the hydration products, while hydroxyl groups participate in hydrogen bonding to anionic and nonionic oxygen atoms. Results in the literature for mechanical properties vary widely for both bare and modified filler, so any added benefits with functionalization are not clearly evident. This mini-review seeks to resolve the issue using an analysis of reports where direct comparisons of cementitious composites with plain and functionalized nanotubes were made at the same concentrations, with the same methods of preparation and under the same conditions of testing. A focus on observations related to the mechanisms underlying the enhancement of mechanical strength and conductivity helps to clarify the benefits of using functionalized MWCNTs. Full article
(This article belongs to the Special Issue Synthesis and Application of Nanoparticles in Novel Composites)
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