Adhesion Science Research Articles

Fracture strength and marginal and internal adaptation of lithium disilicate and hybrid ceramic endocrowns and non-retentive overlays for endodontically treated molar teeth

BackgroundWith the advances in the adhesive science, several conservative treatment options such as non-retentive overlays have been suggested for endodontically treated posterior teeth. However, information is scarce regarding the fracture strength and adaptation of non-retentive overlays compared with endocrowns, and the effect of material type in this respect. Thus, this study aimed to assess the fracture strength and internal and marginal adaptation of lithium disilicate (LDS) and hybrid ceramic endocrowns and non-retentive overlays for endodontically treated molar teeth.MethodsThis in vitro study was conducted on 40 endodontically treated molar teeth that were randomly assigned to 4 groups based on the restoration type and material type (n = 10): LDS and hybrid ceramic endocrowns, and LDS and hybrid ceramic non-retentive overlays. The internal and marginal adaptation of restorations were assessed by the silicone replica technique. After cementation and thermomechanical loading, the fracture strength was measured, and the failure mode was determined. Data were analyzed by two-way ANOVA with pairwise comparisons with the Tukey’s test, and Fisher’s exact test (α = 0.05).ResultsThe highest mean marginal and internal gaps were recorded in hybrid ceramic endocrowns, followed by LDS endocrowns, hybrid ceramic overlays, and LDS overlays. All pairwise comparisons revealed significant differences (P < 0.001) except the two endocrown groups, which were not significantly different regarding internal gap (P = 0.998). The mean fracture strength was the lowest in hybrid ceramic endocrowns, followed by hybrid ceramic overlays, LDS endocrowns, and LDS overlays. All pairwise comparisons revealed significant differences (P < 0.05) expect the two hybrid ceramic groups (P = 0.180). No significant difference was found in the failure mode among the groups (P = 0.312).ConclusionsType of restoration and material significantly influenced both adaptation and fracture strength. Specifically, LDS overlays on endodontically treated molar teeth yielded the highest fracture strength and superior internal and marginal adaptation in comparison with other material.

Mechanics-Switchable and Antiswelling Colloidal Hydrogels Inspired by the Cononsolvency Effect.

Stiffness switching hydrogels have been in high demand for intelligent devices, adhesion science, soft robotics, and flexible electronics. However, it is challenging to post-tune the mechanical properties of a hydrogel once the polymer network structure is formed. Inspired by the cononsolvency effect, we prepared a mechanics-switching colloidal hydrogel through the precipitation polymerization of methacrylamide in mixed dimethyl sulfoxide and water solvents. The colloidal network enables the hydrogels to simultaneously strengthen, stiffen, and toughen. The colloidal hydrogels not only display a broad spectrum of adjustable mechanical properties (ranging from 0.08 to 57.1 MPa) via solvent response but also accomplish reversible stiffness conversion through the solvent-tuned conformational adjustment of colloidal polymer networks, with the maximum modulus conversion reaching 1427, and exhibit solvent-responsive shape memory. Based on the stable and tight colloidal network, the hydrogels exhibit antiswelling properties in various aqueous solutions and solvents. The colloidal hydrogel would provide more possibilities in various applications, such as antiimpact protection, shape memory, electronic switches, and intelligent engineering materials. It is envisioned that this work will provide key opportunities in developing mechanics-switching and on-demand tuning of soft materials for tissue engineering, flexible electronics, and biomedical science.

Electrochemical Detection of Ornidazole By Means of an Electrode Modified with Copper-Iron Nanoparticles and Carbon Black

Antibiotics have become fundamental tools in our fight against disease but their accumulation in the aquatic environment due to discharges from manufacturing plants, hospitals and farms, and to misuse by the public has seen them emerge as water pollutants. Their presence constitutes a serious environmental and health risk due to their toxicity and due to the risk of antimicrobial resistance (AMR), which may render antibiotics ineffective when employed to fight infection. Assessing the impact of antibiotic pollution on water quality, drinking water, recreational/bathing water, and the impact on life is critical for our health and wellbeing.Ornidazole is a member of the nitroimidazole antibiotic family that is heavily employed in the treatment of both human and animal infections [1]. This widespread use has led to the accumulation of the antibiotic in aquatic environments, posing a serious health risk due to its toxicity and the risk of AMR [2]. For this reason, novel and environmentally friendly methods of rapidly and accurately detecting its presence in the environment are vital to mitigate its pollution and harmful effects.In this study two materials are combined to enhance the conductivity and ability of a glassy carbon electrode sensor to detect ornidazole. Carbon black, a material composed of 95% carbon with a structure similar to graphite [3] is functionalized using a novel green method with tannic acid. This is then combined with a layered double hydroxide (LDH) to act as a source of metal nanoparticles. LDH’s are a combination of transition metals with the general formula [M1-x 2+M3+ x(OH)2]x+(An-)x/n.mH2O where M is two different metals and A is the intercalated anion between the stacked layers of M2+/M3+ ions to produce a 2D layered nanosheet structure [4]. These LDHs are synthesized hydrothermally, which involves combining sources of the desired metals into a sealed autoclave and heating to produce a high vapour pressure environment.Functionalized carbon black was dispersed and drop-casted onto the surface of the electrode. After drying, it was decorated by means of drop-casting with a dispersion of the LDH containing the desired elements. The LDH is then easily reduced by means of cyclic voltammetry to embed the nanoparticles of the desired elements into the carbon black, producing a stable modified electrode. LDH’s containing a variety of elements were investigated for their ability to detect ornidazole. The optimum element combination was concluded to be copper-iron nanoparticles. The procedure for the synthesis and modification of the electrode can be seen in Figure 1.The carbon black-copper iron (CuFe) modified sensor shows excellent sensitivity compared to bare glassy carbon and is capable of detecting ornidazole concentrations from 0.2 μM to 600 μM, displaying excellent stability over multiple uses. Studies were performed to characterize the carbon black-CuFe material using SEM, XRD, XPS, FTIR, and EDX. Investigations were carried out into the behaviour of the sensor at varying pH values and to determine the reaction kinetics of detection. To study the selectivity of the sensor interferants were introduced to the antibiotic solution and experiments were performed in real water samples gathered from various locations.[1] Q. Wang, C. Wang, Q. Wang, & Z. Wang, Journal of Agricultural and Food Chemistry., 2019, 67(41), 11527-11535[2] W. El, N. Tajat, A. Idelahcen, M. Tamimi, S. Qourzal, A. Assabbane, & I. Bakas, Microchemical Journal, 2023, 195, 109397[3] J. M. Martín-Martínez, Adhesion Science and Engineering : Surfaces, Chemistry and Applications, 2002, Chapter 13, 573-675[4] A., Karmakar, K., Kannimuthu, S., Sam Sankar, K., Sangeetha, R., Madhu, & S., Kundu. Journal of Materials Chemistry A. 2020 Figure 1

RETRACTED ARTICLE: Investigating the strength of butt-welded joints of AA6082 and AA5052 alloys through friction stir welding; the impact of tool tilt angle and feed rate

We, the Editors and Publisher of the Journal of Adhesion Science and Technology, have retracted the following article: Investigating the strength of butt-welded joints of AA6082 and AA5052 alloys through friction stir welding; the impact of tool tilt angle and feed rate. Journal of Adhesion Science and Technology, https://doi.org/10.1080/01694243.2023.2253631. Bhiksha Gugulothua, Rajasekaran Saminathan, A. Pradeep, Ankit Sharma, S. Vijayakumar, Prabhu Paramasivam, and N. Srinivasa Rao. (2023). Since publication, concerns have been raised by a third party about the integrity of the data presented in the article, as well as potential authorship concerns. When approached for an explanation, the authors have been unable to provide their original data to verify its authenticity. In addition, the authors have not fully responded to our questions regarding the process of the research conducted. We have been informed in our decision-making by editorial policies and the COPE guidelines. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

The science and mechanics of adhesion: An industrial view.

Undoubtedly, adhesion is one of the broadest terms in science and technology used to describe several bulk and interface related phenomena. While the thermodynamic work of adhesion is determined by contacting surfaces and their intrinsic surface energetics, it is important to understand how adhesive properties of materials are additionally governed and amplified by their dissipative rate processes in the bulk or near the interface as they go through large strains and deformation. Systematic review of the literature showed that the involved interfacial mechanisms were grouped into several categories ranging from micromechanical interlocking to molecular interdiffusion of surface constituents, a characteristic of most polymeric systems. This paper addressed the static and dynamic contributions to the adhesion energy and discussed its relation to microstructure and surface architecture in pressure sensitive and fracture in structural adhesives. While the focus was on industrial view of adhesion, parallels in adhesive dentistry were given where connections between adhesion, boundary geometry/compliance, shrinkage stress, material model, joint design, retention, and interfacial curing were made. Adhesion science and mechanics are complex multi-disciplinary fields involving surfaces, substrates, and loading system involving a broad range of mechanisms applicable to dentistry.

Molecular Science of Adhesion: Approach from First-Principles Calculation

Molecular Science of Adhesion: Approach from First-Principles Calculation

Functional Asymmetry-Enabled Self-Adhesive Film via Phase Separation of Binary Polymer Mixtures for Soft Bio-Integrated Electronics.

Biocompatible adhesive films are important for many applications (e.g., wearable devices, implantable devices, and attachable sensors). In particular, achieving self-adhesion on one side of a film with biocompatible materials is a compelling goal in adhesion science. Herein, we report a simple and easy manufacturing process using water-soluble hyaluronic acid (HA) that allows adhesiveness on only one side using binary polymer mixtures based on a phase-separation strategy with an elastomer. HA influx allows for the entangled polymer chains of the elastomer to spontaneously deform, permitting tunable mechanical elasticity, conformability, and adhesion. The proposed adhesive film enables the transfer of nanopatterning and the attachment of various surfaces without the use of additional chemicals. In addition, the film can be used for measuring epidermal biopotential and for skin fixation of drug devices. Therefore, the developed facile asymmetric adhesion can block the interferences of other materials on the unnecessary adhesion side, providing considerable potential for the development of functional, multifunctional, and smart bioadhesives.

Interfacial Electrochemistry-Induced Detachable Adhesives with Ultra-High Bonding Strength and Detaching Efficiency.

Detachable adhesives with simultaneously high bonding strength and detaching efficiency have remained a great challenge in adhesion science. The existing detachable adhesives (e.g., solid-liquid phase transitions-based adhesives) usually show low initial cohesion and require long detaching time (several minutes or hours for transitions). Herein, by introducing ionic liquids (ILs) and soft polyethylene glycol (PEG) into a rigid epoxy precursor and curing, we demonstrated the adhesives with both high initial bonding strength (>13 MPa) and detaching efficiency (100% detachment within 10 s under a 90 V DC voltage). The high initial bonding strength is due to the imidazolium cations of ILs and their ion-dipole interactions with PEG can promote the curing of epoxy, decrease the glass-transition temperature, increase the interfacial wettability, and transmit external stress. Also, the outstanding detaching efficiency is because the tetrafluoroborate anions of ILs can electrochemically react rapidly under a voltage and generate fluorinated nanoparticles at the bonding interface within 1 minute. The high bonding and electrochemistry-induced detaching mechanism were further characterized. This work opens up a new avenue for the rational design of fast-detachable adhesives with high bonding strength, showing wide potential in many modern fields.

Recent Advances in Mucoadhesive Interface Materials, Mucoadhesion Characterization, and Technologies

AbstractMucoadhesion is an extremely important field of adhesion science and the comprehensive understanding and modulation of mucoadhesion can lead to lifesaving materials and technologies. For instance, deadly cases of COVID‐19 (SARS‐CoV‐2) cytokine storm are associated with viral adhesion and overproduction of mucus, which obstructs the airways. Mucin is the key polymeric compound that is known as a family of high molecular weight, heavily glycosylated proteins in epithelial tissues. Mucoadhesion can occur in many different ways such as receptor specific and charge interactions, covalent or noncovalent bonds. New mucin‐mimic polymers that replicate its beneficial traits can prevent biofilm formation and biofouling not only in biotechnology but also in membrane technologies. This review addresses the latest understandings related to mucin's role in wet adhesion considering different physiological conditions and shows how this translates into interfacial polymer adhesion. Advances in mucoadhesion measurement techniques including the rheological aspects of polymer–mucin adhesive interactions are presented. Specific mucoadhesive systems are discussed such as hydrogel mucoadhesion, catechol/dopamine functionalization, and polymeric nanoparticles. This overview may expand the current understanding of mucoadhesion between soft materials but also contributes to elastocapillary phenomena in soft materials design and applications such as new membranes, drugs, pharmaceutical devices, and lubricated surfaces.

Influence of Nanofillers on Adhesion Properties of Polymeric Composites.

Nanofillers (NFs) are becoming a ubiquitous choice for applications in different technological innovations in various fields, from biomedical devices to automotive product portfolios. Potential physical attributes like large surface areas, high surface energy, and lower structural imperfections make NFs a popular filler over microfillers. One specific application, where NFs are finding applications, is in adhesive science and technology. Incorporating NFs in the adhesive matrix is seen to tune the adhesives’ different properties like wettability, rheology, etc. Additionally, the functional benefits (like electrical/thermal conductivity) of these NFs are translated into the adhesives’ properties. Such an improvement in the properties is far to achieve using microfillers in the adhesive matrix. This mini-review provides an account of the impact of the addition of various nanofillers (NFs) on the properties of the adhesive composition.

Retention in maxillofacial prosthetics: A review

The facial region defects caused by trauma, accident, tumour or congenital defects are treated with maxillofacial prostheses. A part from esthetics, the most common problem encountered with these prostheses is the retention of prostheses. Recent techniques along with newer materials, treatment options, and its application are described. The success of maxillofacial prostheses in meeting the expectations of patients and prosthodontists is on rise with the development of adhesive material science, the emergence of technical knowledge, and the development of implant technology. Increase in retention provides ease of use and psychological acceptance by the patient thereby improving the long-term prognosis of the prosthesis. In the present article review, the methods used for the retention of prostheses from past to present along with the advantages of adhesives and implants, implementation of 3D technology and rapid prototyping were critically appraised.

A research on the fatigue strength of the single-lap joint joints bonded with nanoparticle-reinforced adhesive

Nano-technological developments, which have made significant progress in recent years, have significant impact on the science of adhesives. Therefore, in our study, the static and fatigue strengths of single-lap joints (SLJs) incorporating nanoparticles were compared to those without nanoparticles. Steel plates were used in the adhesive joints. The results revealed that average damage load increased significantly in nanoparticle-reinforced adhesive joints. The highest damage load was obtained with 4 wt% nano-Al2O3 in epoxy adhesive. As the average damage load increased, the locus of damage changed from interfacial to the mixture of interfacial and cohesive. Also, fatigue strengths of the joints increased when the adhesive joint had nano-Al2O3 and nano-SiO2, and decreased when the adhesive joint had nano-TiO2.

Current perspectives on dental adhesion: (3) Adhesion to intraradicular dentin: Concepts and applications

Adhesion science is one of the greatest contributions to restorative dentistry. Adhesion not only established the current principles of tissue preservation, but also allowed for the production of more hermetic and long-lasting restorations. Although adhesive strategies are routinely used in most clinical situations, adhesion to root dentin is still a major challenge. The presence of humidity together with less intertubular dentin are factors that limit the adhesive potential of root dentin. This situation is more unfavorable in endodontically treated teeth prepared for prefabricated or custom-made intraradicular posts; these procedures may alter the mechanical properties of teeth by modifying the viable dentin surface for adhesion. Also, contaminants deposited on the dentin surface are difficult to remove through conventional techniques. Moreover, root canal morphology has a very unfavorable C-factor, bringing undesirable effects resulting from polymerization contraction of resin-based materials. However, the differences between coronal and root dentin are not a barrier for dentin adhesion. Standardization of procedures and care during clinical steps are fundamental to the success of adhesion to coronal or intraradicular dentin. Thus, it is essential to know the anatomy of the root structure, the factors that interfere with intraradicular adhesion, as well as the current adhesive materials and techniques.

A mechanism for temporary bioadhesion

The flatworm Macrostomum lignano features a duo-gland adhesive system that allows it to repeatedly attach to and release from substrates in seawater within a minute. However, little is known about the molecules involved in this temporary adhesion. In this study, we show that the attachment of M. lignano relies on the secretion of two large adhesive proteins, M. lignano adhesion protein 1 (Mlig-ap1) and Mlig-ap2. We revealed that both proteins are expressed in the adhesive gland cells and that their distribution within the adhesive footprints was spatially restricted. RNA interference knockdown experiments demonstrated the essential function of these two proteins in flatworm adhesion. Negatively charged modified sugars in the surrounding water inhibited flatworm attachment, while positively charged molecules impeded detachment. In addition, we found that M. lignano could not adhere to strongly hydrated surfaces. We propose an attachment-release model where Mlig-ap2 attaches to the substrate and Mlig-ap1 exhibits a cohesive function. A small negatively charged molecule is secreted that interferes with Mlig-ap1, inducing detachment. These findings are of relevance for fundamental adhesion science and efforts to mitigate biofouling. Further, this model of flatworm temporary adhesion may serve as the starting point for the development of synthetic reversible adhesion systems for medicinal and industrial applications.

Interaction of Poly(dimethylsiloxane) and octamethylcyclotetrasiloxane with aluminum oxides comprising different acid-base properties

Interactions between polymer matrices and inorganic mineral surfaces are especially relevant in polymer-filler composites and in adhesion science. Knowledge about underlying mechanisms at the interphase is a prerequisite for understanding functionality and aging. Therefore, interactions of poly(dimethylsiloxanes) (PDMS) and octamethylcyclotetrasiloxane (D4) with aluminum oxides comprising different acid-base properties were studied. For this purpose, thin layers of siloxanes were applied on aluminum oxides and analyzed by Raman spectroscopy and thermogravimetric analysis. It was observed that aluminum oxides are able to react with PDMS and D4 by heterolytic bond cleavage of SiO bonds, either by reactions with physisorbed water under catalysis of aluminum oxide or by direct reaction of the surface with siloxanes. Both reaction paths can yield SiOAl bonds and thus chemisorption which lead to strong interactions between siloxanes and aluminum oxides. However, the shown reaction paths concomitantly act as aging mechanisms leading to degradation of polymer.

Retention systems used in maxillofacial prostheses: A review.

Defects in the face area caused by trauma, accident, tumor or congenital defects are treated with special facial prostheses. Besides esthetics, the most common problem with these prostheses is the retention of prostheses. In the present article review, the methods used for the retention of prostheses from past to present were researched, and the advantages of adhesives and implants, which are the most commonly used current methods, were evaluated. Current techniques, new materials, treatment options, and implementation procedures are described. The success of maxillofacial prostheses in meeting the expectations of patients and dentist doctors is increasing day by day with the development of adhesive material science, the emergence of technical knowledge, and the development of implant technology. Increasing the retention provides both ease of use and acceptance by the patient. Therefore, the chosen method for retention has great importance in the long-term prognosis of the prosthesis.

How valid is Taylor dispersion formula in slugs?

How valid is Taylor dispersion formula in slugs?

Bio-inspired reversible underwater adhesive

The design of smart surfaces with switchable adhesive properties in a wet environment has remained a challenge in adhesion science and materials engineering. Despite intense demands in various industrial applications and exciting progress in mimicking the remarkable wet adhesion through the delicate control of catechol chemistry, polyelectrolyte complex, and supramolecular architectures, the full recapitulation of nature’s dynamic function is limited. Here, we show a facile approach to synthesize bioinspired adhesive, which entails the reversible, tunable, and fast regulation of the wet adhesion on diverse surfaces. The smart wet adhesive takes advantage of the host–guest molecular interaction and the adhesive nature of catechol chemistry, as well as the responsive polymer, allowing for screening and activation of the interfacial interaction simply by a local temperature trigger in an on-demand manner. Our work opens up an avenue for the rational design of bioinspired adhesives with performances even beyond nature.

Reaction: Benign by Design Demands Innovation

Prof. Long joined the Department of Chemistry in 1999 after holding positions at Eastman Kodak and Eastman Chemical, and he currently serves as the director of the Macromolecules Innovation Institute at Virginia Tech. Recent recognitions include an AAAS fellowship, ACS fellowship, ACS PMSE Cooperative Research Award, ACS POLY Mark Scholar Award, and the 2015 Virginia Outstanding Scientist award. His interdisciplinary research program focuses on structure, property, processing, and performance relationships of tailored macromolecules. Current interests include materials for additive manufacturing, photo-reactive polymers, block and segmented copolymers, polymer packaging, ion-containing polymers, adhesive science, and high-performance engineering polymers.

CH/π Interactions for Macroscopic Interfacial Adhesion Design

Adhesion to chemically inert materials without surface modification through noncovalent interactions represents a challenging task in adhesion science. We successfully develop for the first time a strategy utilizing multiple CH/π interactions that use poly(methacrylate) with an aromatic group (H acceptor) in the ester part and polyolefin materials (H donor). The strength increases with the number of π electrons and aromatic rings. The trityl methacrylate polymer emerges as the most effective H-acceptor polymer for obtaining strong adhesion to various polyolefin materials. This work will provide not only a promising adhesion strategy that does not require surface activation for polyolefin materials, but also a novel approach using weak noncovalent interactions.