Adhesive Material Research Articles

A comparative study of polydopamine vs. glass ionomer cement for adhesion mechanisms on enamel and dentin using SEM and shear bond strength evaluation

Polydopamine (PD), inspired by the wet adhesion mechanism of mussel foot proteins, has emerged as a promising adhesive material with wide-ranging applications. This study aimed to compare the adhesive properties of PD and Glass Ionomer Cement (GIC) on enamel and dentin substrates, evaluating PD’s potential as an alternative adhesive in dental practice. A total of 120 human premolars were prepared, with 80 teeth allocated for Scanning Electron Microscopy (SEM) analysis and 40 teeth reserved for shear bond strength testing. The 80 teeth for SEM were divided into four groups (n = 20 per group) based on the adhesive used (PD or GIC) and the substrate (enamel or dentin). The bond interfaces were analysed under SEM following adhesive self-polymerization. Statistical analysis using the Mann-Whitney U test (p < 0.05) revealed that GIC and PD showed more microcracks when bonded to dentin compared to enamel, with the PD-enamel group showing the fewest microcracks. For shear bond strength testing, the 40 remaining teeth were divided into four groups (n = 10 per group) according to the same adhesive-substrate combinations. The results analysed using the Kruskal-Wallis test (p < 0.001), indicated that PD bonded to enamel exhibited the highest bond strength, followed by PD-dentin, GIC-enamel, and GIC-dentin. These findings were consistent with the SEM analysis, demonstrating that PD provides superior bonding to enamel and outperforms GIC in both bond strength and interface quality. This study suggests that PD is a viable alternative to GIC, particularly for enamel bonding, and further research is recommended to assess its long-term clinical performance.

The Most Promising Alternative to Mercury-containing Dental Restorations

The European Union Environmental Commission report and the United Nation Minamata Convention have legislated for phasing-out of mercury-containing dental materials use (dental amalgams) by 2030.1, 2 Several Scandinavian countries have already banned the use of dental amalgams, and this ban is expected to grow to other countries worldwide.2, 3 This creates a market gap for materials which can be used as an alternative to dental amalgams.4 Varieties of mercury-free dental materials have been clinically approved as posterior restorations; such as (1) resin-based composite materials, and (2) glass-based materials, including glass ionomers and glass hybrids. Using these types of dental materials will decrease the mercury’s risks on human’s health and also contribute significantly in the reduction of the environmental mercury pollution.5, 6 Recently, several clinical approaches to treat dental caries lesions have shifted the focus to preserving tooth structure and use of adhesive materials. Considering this, Minimally Intervention Dentistry (MID) has become a crucial concept which includes three aspects to fulfil the requirement of preventive and restorative dentistry; these are early caries diagnosis, enhance remineralisation and minimal cutting of tooth surfaces.7, 8 This approach is identified as an Atraumatic Restorative Treatment (ART). The ART technique was adopted in 1994 by the World Health Organisation (WHO) as an alternative technique for dental caries management in the developed countries either for treating deciduous and/or permanent dentitions.9 The high viscous glass ionomer cement (GIC) is approved as an ideal candidate material to be used with ART technique; such as GC Fuji IX®, KetacTM Molar and Glass Carbomer®.10, 11 One of the main advances in dental materials field is based on the modifications of the GIC chemical compositions, by introducing a bioactive glass in different particle sizes (for promoting remineralising ability) and/or using a highly molecular weight of poly- acrylic acid (for enhancing matrix strength).12 When bioactive glass-containing dental materials come into contact with body fluid, will undergo to a sequence of bioactivity reactions; which is summarised into (1) ion exchange, (2) dissolution and (3) precipitation stages, leading to formation of apatite crystals in fractions identical to those of the natural bone and tooth components.13 Formation of apatite crystals [hydroxyapatite-Ca10(PO4)6OH2 or fluorapatite-Ca10(PO4)6F2] in the bioactive glass-containing GICs occurs via delivering of calcium (Ca2+), phosphate (PO43), hydroxyl (OH-) and/or fluoride (F-) species at the interfaces between the GIC/tooth surfaces and/or the GIC/oral environment.14 For this reason, the bioactive glass-containing GICs are considered as the most promising alternative restorative materials for posterior cavities.

Effect of a chemically-modified-curcumin on dental resin biodegradation

IntroductionPrevious studies have shown Streptococcus mutans (S. mutans) esterase is a key mediator of dental composite biodegradation, which can contribute to recurrent caries. This study is to investigate the inhibitory effects of a novel Chemically-Modified-Curcumin (CMC 2.24) on esterase activities and related dental material biodegradation.MethodsDental adhesive materials and composite resins were incubated in S. mutans suspension with CMC 2.24 and other compounds, including doxycycline, Chemically-Modified-Tetracycline (CMT-3), and curcumin for 4 weeks. The pre- and post-incubation surface roughness were evaluated by either laser diffraction pattern and/or a 3D laser scanning microscope. Esterase enzyme inhibition assays were performed with the same test groups and activities were determined spectrophotometrically.ResultsAmong all experimental groups, CMC 2.24 significantly reduced surface roughness of dental composite (p &amp;lt; 0.01) and adhesive (p &amp;lt; 0.01) materials compared to bacteria-only group. Additionally, CMC 2.24 reduced porcine esterase activity by 46.5%, while other compounds showed minimal inhibition. In the S. mutans esterase assay, CMC 2.24 showed inhibition of 70.0%, while other compounds showed inhibition ranging from 19% to 36%.ConclusionOur study demonstrated that CMC 2.24 inhibited biodegradation of dental composite material more effectively than its mother compound, curcumin. Moreover, the mechanism of this biodegradation was likely mediated through bacterial esterase activity. Doxycycline achieved similar inhibition by completely eradicating S. mutans with its antibiotic action; hence, it is not recommended for long-term use.

Polymerization characteristics of orthodontic adhesives: a study on degree of conversion

Relevance. Adhesive materials play a crucial role in orthodontic treatment. The introduction of universal bonding agents to the dental market offers greater flexibility in choosing adhesive protocols for clinical use. However, many studies evaluating the mechanical properties of adhesives, such as shear and tensile bond strength, fail to address the degree of conversion of polymerized bonding materials beneath brackets.Objective. To compare the degree of conversion between a universal adhesive system and a total-etch system for orthodontic applications.Materials and methods. The study compared the Transbond XT total-etch system (3M Unitek, USA) with the Tetric N-Bond Universal system (Vivadent Ivoclar, Liechtenstein). Four groups of five samples each (n = 5) were analyzed. Groups 1 and 2 involved polymerization without brackets, while Groups 3 and 4 involved polymerization under metal brackets (Gemini, 3M Unitek, USA). Spectra were recorded immediately after polymerization for 15 minutes using Fourier-transform infrared spectroscopy (FTIR). Statistical analysis included the Shapiro–Wilk test, analysis of variance (ANOVA), and Tukey's multiple comparison test, with a significance level of p &lt; 0.05.Results. The mean degree of conversion in the control groups was 55.9% ± 0.44 for Group 1 and 66.72% ± 0.15 for Group 2. A reduction in conversion was observed in specimens polymerized under metal brackets compared to the control groups. The mean conversion in Group 3 was 36.02% ± 0.19, which was 1.1% lower than in Group 4 (37.1% ± 0.16).Conclusion. The universal adhesive Tetric N-Bond Universal demonstrated superior polymerization performance for orthodontic applications compared to the total-etch adhesive system.

New future dental material: Antimicrobial material "cetylpyridinium chloride-montmorillonite" and implantable material "phosphorylated pullulan".

In dental practice, there are two major diseases: dental caries and periodontal disease. Although dental treatment techniques have advanced along with advances in dental materials, some diseases such as root surface caries and horizontal bone resorption have not yet achieved satisfactory treatment results. Since these diseases are infections caused by oral bacteria, we believe that materials with long-lasting antimicrobial properties would help control these diseases. In addition, materials that can adhere to wet hard tissues would contribute to treatment. In this review, new materials developed based on this idea, the antimicrobial material "cetylpyridinium chloride-montmorillonite" and the hard tissue adhesive implantable material "phosphorylated pullulan" was introduced.

Crosslinking-induced compatibility and toughness enhancement in poly(lactic acid)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) blends with epoxidized soybean oil.

Polylactide (PLA) is inherently brittle and lacks ductility, which greatly restricts its range of applications. In order to address these issues, we blended PLA with biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)), and introduced epoxidized soybean oil (ESBO) as a reactive modifier to enhance the properties of the PLA/P(3HB-co-4HB) blends. Furthermore, we used theoretical calculations, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Soxhlet extraction, differential scanning calorimetry (DSC), polarising optical microscopy (POM), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mechanical testing to investigate the compatibility, crystallization behavior, microstructure, thermal and mechanical properties of the PLA/P(3HB-co-4HB)/ESBO blends. The mechanisms underlying these properties were analyzed in detail. ESBO was found to form cross-linking grafts between PLA and P(3HB-co-4HB), strengthening interfacial bonding and thereby enhancing compatibility. The in situ formation of graft copolymers resulted in finer, more uniform dispersion of P(3HB-co-4HB) and ESBO droplets within the PLA matrix, further improving interfacial adhesion and overall material compatibility. With the addition of 5 wt% ESBO, the tensile strain at break of PLA/P(3HB-co-4HB)/ESBO films increased from 114.6 % to 453.3 %, while the notched impact strength improved from 3.75 kJ∙m-2 to 8.75 kJ∙m-2, compared to PLA/P(3HB-co-4HB) films. However, excessive ESBO slightly decreases the mechanical performance of the material.

Tailoring thermal conductivity and printability in boron nitride/epoxy nano- and micro-composites for material extrusion 3D printing

This study explores the design and characterization of boron nitride (BN)/epoxy nano- and micro-composites, utilizing material extrusion 3D printing as a powerful technique to align filler particles within the matrix and produce effective thermally conductive and electrically insulating adhesive materials with possible applications in electronics. Investigating the uncharted correlation between filler morphology, including both boron nitride microplatelets (BNMP) and boron nitride nanosheets (BNNS), processability by additive manufacturing (AM), and ink functionalities, BNMP proves more effective in boosting thermal conductivity, with an enhancement of up to 400%. Fillers, that can be highly oriented through material extrusion, contribute to achieving high glass transition temperature (up to 137 °C) and thermal resistance, expanding the inks’ applicability. Optimized inks demonstrate exceptional shape fidelity, enabling the fabrication of complex structures. The findings emphasize the crucial role of ceramic filler content and morphology in optimizing multifunctional 3D-printed materials' performance and tailoring their properties, offering insights for future innovations in electronic materials and manufacturing methodologies for thermal management applications.

Research on advanced photoresponsive azobenzene hydrogels with push-pull electronic effects: a breakthrough in photoswitchable adhesive technologies.

Smart materials that adapt to various stimuli, such as light, hold immense potential across many fields. Photoresponsive molecules like azobenzenes, which undergo E-Z photoisomerization when exposed to light, are particularly valuable for applications in smart coatings, light-controlled adhesives, and photoresists in semiconductors and integrated circuits. Despite advances in using azobenzene moieties for stimuli-responsive adhesives, the role of push-pull electronic effects in regulating reversible adhesion remains largely unexplored. In this study, we investigate for the first time photo-controlled hydrogel adhesives of azobenzene with different push-pull electronic groups. We synthesized the monomers 4-methoxyazobenzene acrylate (ABOMe), azobenzene acrylate (ABH), and 4-nitroazobenzene acrylate (ABNO2), and examined their effects on reversible adhesion properties. By incorporating these azobenzene monomers into acrylamide, dialdehyde-functionalized poly(ethylene glycol), and [3-(methacryloylamino)propyl]-trimethylammonium chloride, we prepared ABOMe, ABH, and ABNO2 ionic hydrogels. Our research findings demonstrate that only the ABOMe ionic hydrogel exhibits reversible adhesion. This is due to its distinct transition state mechanism compared to ABH and ABNO2, which enables efficient E-Z photoisomerization and drives its reversible adhesion properties. Notably, the ABOMe ionic hydrogel reveals an outstanding skin adhesion strength of 360.7 ± 10.1 kPa, surpassing values reported in current literature. This exceptional adhesion is attributed to Schiff base reactions, monopole-quadrupole interactions, π-π interactions, and hydrogen bonding with skin amino acids. Additionally, the ABOMe hydrogel exhibits excellent reversible self-healing capabilities, significantly enhancing its potential for injectable medical applications. This research underscores the importance of integrating multifunctional properties into a single system, opening new possibilities for innovative and durable adhesive materials.

Polydopamine-mediated gold nanoparticle coating strategy and its application in photothermal polymerase chain reaction.

Materials with high light-to-heat conversion efficiencies offer valuable strategies for remote heating. These materials find wide applications in photothermal therapy, water distillation, and gene delivery. In this study, we investigated a universal coating method to impart photothermal features to various surfaces. Polydopamine, a well-known adhesive material inspired by mussels, served as an intermediate layer to anchor polyethyleneimine and capture gold nanoparticles. Subsequently, the coated surface underwent electroless gold deposition to improve photothermal heating efficiency by increasing light absorption. This process was analyzed through scanning electron microscopic imaging and absorbance measurements. To demonstrate functionality, the coated surface was photothermally heated using a light-emitting diode controlled with a microprocessor, targeting the metal regulatory transcription factor 1 gene-a marker for osteoarthritis-and the S gene of the severe fever with thrombocytopenia syndrome virus. Successful amplification of the target genes was confirmed after 34 polymerase chain reaction cycles in just 12 min, verified by gel electrophoresis, demonstrating its diagnostic applicability. Overall, this simple photothermal coating method provides versatile utility, and is applicable to diverse surfaces such as membranes, tissue culture dishes, and microfluidic systems.

Comparison of high viscosity glass Ionomer cement and Alkasite as restorative material for atraumatic restorative treatment - a randomized controlled trial with split mouth design

Background. Atraumatic Restorative Treatment (ART) is widely used for managing dental caries, emphasizing minimal intervention and adhesive restorative materials. High Viscosity Glass Ionomer Cement (HV-GIC) and Alkasite an emerging material, warrant clinical evaluation to determine their performance in long-term. Objectives. To evaluate the clinical performance of Alkasite and High Viscosity Glass Ionomer Cement (HV-GIC) as restorative materials in Atraumatic Restorative Treatment for primary molars. Materials and methods. Thirty children with bilateral class I cavities (n-60) were allocated in random into Group-1 Alkasite and Group-2 High Viscosity-Glass Ionomer Cement (HV-GIC). Restoration were evaluated at the 3rd and 6th months through Modified USPHS criteria (1980) and Modified Clinical Criteria for ART (1996). Fisher's exact test and Kaplan-Meier survival analysis were used which was carried out using IBM SPSS Statistics for Windows, Version 26.0. Results. Restorations evaluated using modified USPHS criteria scored either Alpha (successful) or Bravo (clinically acceptable). At the 6th month follow-up 100% (n = 30) alpha score was obtained in criteria like Fracture, Secondary Caries, Post-operative sensitivity, Surface roughness, and Retention. Under Anatomic form and Marginal adaptation categories, the HV-GIC group scored 100% (n = 30) alpha and the Alkasite group scored 90% (n = 27) alpha at both 3rd and 6th month follow-up but this difference was statistically insignificant (p &gt;0.05). Additionally, score 0 (restorations present and good) was obtained in Modified Clinical Criteria for Evaluations of ART for all 30 (100%) restorations in HV-GIC group and 27 restorations (90%) in the Alkasite group at the end of 6 months (p &gt;0.05). Conclusions. This study demonstrated that both HV-GIC and Alkasite had clinically acceptable outcomes in restoring dental cavities using Atraumatic Restorative Treatment for primary molars.

Comparison of survival time of three adhesive materials used in fixed space maintainer cementation by using ball milling machine: An in vitro study

Background: Premature primary tooth extraction causes loss of arch length, therefore; space preservation is a critical step to prevent space closure that can lead to future malocclusion. This can be achieved by using a space maintainer. Thus study's objective was to assess and contrast the survival of three different luting materials used to cement fixed space maintainers an in vitro study. Materials and Methods: This study used 30 extracted human third molars without caries, cracks, or chemical pretreatment. They were divided into three groups of ten samples (n = 10). The adhesives selected in this study were Relyx Luting 2 (resin modified glass ionomer), TOTALCEM (self-etching, self-adhesive, resin cement, dual cure) and Transbond Plus Light Cure band adhesive (compomer). Manufacturer recommendations for bonding were followed after cleaning and polishing for all surfaces of the teeth. To distinguish the specimens, the middle of the root was drilled with a handpiece and marked with a red marker, then incubated for 24 h at 37 °C before being transferred to a ball mill machine to induce mechanical stress. The machine was opened to check for any failed specimen. This continued until all bands were removed from the teeth. The data was analyzed using log-rank Kaplan-Meier and Bonferroni post hoc tests at p 0.05. Results: the mean survival time of bands cemented with TOTALCEM and RelyX Luting 2 significantly longer than bands cemented with Transbond Plus Light Cure band adhesive (P&lt;0.001). Conclusion: band retention with TOTALCEM and RelyX Luting2 superior than bands cemented with Transbond Plus Light Cure Band Adhesive.

Polymer Entanglement-Induced Hydrogel Adhesion.

Hydrogels are widely used in the field of adhesive materials. However, hydrogel adhesion has previously required the covalent graft of supramolecular groups on polymeric chains. In contrast to that, here, a hydrogel adhesion induced by covalent polymer entanglement between two hydrogel networks was reported. Hydrogels G1 and G2 contain the monomers M1, with diazonium groups, and M2, with sulfonate groups, respectively. When the two hydrogels come into contact, the monomers diffuse into each other's networks and assemble into supramolecular polymers (SPs) based on electrostatic interactions, threading the two hydrogel networks. Subsequently, SPs convert into covalent polymers (CPs) under UV light stimulation due to the reaction between the diazonium groups and sulfonate groups, leading to the entanglement of the two hydrogel networks and the production of an adhesive effect. This finding provides a novel strategy for hydrogel adhesion.

Effect of Counterbody Material on the Boundary Lubrication Behavior of Commercially Pure Titanium in a Motor Oil

Titanium possesses many useful properties and is a technologically important material in engineering. However, lubrication of titanium has long been a problem that has prevented titanium from being more widely used. This is due to its poor tribological properties, deriving from its high tendency towards adhesive wear, material transfer, and abrasive wear. Lubrication is a system engineering which involves material combinations, material surfaces, lubricants, and operating conditions as a system. In this work, the boundary lubrication behavior of commercially pure titanium (CP-Ti) sliding against various counterbody materials in a motor oil (0W-30) was investigated under ball-on-plate reciprocating sliding conditions. The counterbody materials (balls) include CP-Ti, ceramic (Al2O3), steel (AISI 52100), and polymer (nylon). The results show that depending on material combination, the lubricating behavior can be divided into three categories, i.e., (1) lubrication failure (Ti-Ti), (2) improved lubrication but with friction instability (Ti-Al2O3), and (3) effective lubrication (Ti–steel and Ti–nylon). Lubrication failure of the Ti-Ti pair leads to high and unstable friction and severe wear from both the plate and ball, while friction instability of the Ti-Al2O3 pair leads to friction spikes and high wear rates. Effective lubrication of the Ti–steel pair results in low and smooth friction and much-reduced wear rates of the Ti plate by nearly 10,000 times. However, there is a load-dependence of the lubrication effectiveness of the Ti–steel pair. Although the Ti–nylon pair is effectively lubricated in terms of much-reduced friction, the nylon ball suffers from severe wear. The friction and wear mechanisms of the various sliding pairs are discussed in this paper.

High Strength and Dynamically Tunable Adhesion Enabled by Composite Micropillar Arrays Fabricated via Solvent‐Assisted Molding

AbstractThe ability to control adhesion on demand is important for a broad range of applications, including the gripping and manipulation of objects in robotics and manufacturing, and the temporary attachment of wearable devices. Despite recent advances in tunable adhesive materials, most existing solutions have modest adhesion strength and are limited by a compromise between the maximum and minimum adhesion, where increased strength prevents the release of lighter objects. To overcome these challenges, thermally responsive polymers, which can exhibit both high stiffness and a large reduction in stiffness via heating, have the potential to enable strong and tunable adhesion. Here, a microstructured composite adhesive with high strength (&gt;2 MPa) and dynamically tunable adhesion (16×) is realized using a solvent‐assisted molding technique. The adhesive consists of an array of composite micropillars whose small scale and material composition enable strong and tunable adhesion. While thermally actuated systems often have slow response times, it is shown that miniaturization allows response times to be reduced to &lt;1s for heating and &lt;10s for cooling. These strong, fast, and dynamically tunable adhesives offer advantages over existing solutions and can be manufactured for practical adoption through the scalable solvent‐assisted molding technique.

INVESTIGATION OF THE FACTORS AFFECTING THE STRENGTH OF A METAL-RUBBER INTERFACE JOINED BY VULCANIZATION: A REVIEW

Metal-rubber parts are used in many sectors because of their ability to combine the advantages of both rubber and metals. Thanks to the advances acquired as a result of the studies carried out by researchers and industries, the usage area of metal-rubber parts expands day by day. The focus of researchers in this field continues to be on achieving effective joints, improving their durability, and ensuring their preservation, as these composites find wide-ranging use. In particular, the positive effects of newly developed surface treatments and adhesive materials on bond strengths have been observed in recent years. Within the scope of this study, the metal-rubber bonding mechanism, vulcanization, bonding during/after vulcanization, some standards related to rubber, bond failures, and their causes are investigated. This review focuses on studies addressing the factors influencing the interfacial strength of metal-rubber bonds joined by vulcanization. Additionally, it provides information on studies and their findings up to date regarding the effects of vulcanization parameters, corrosive environments, components in the bonding process, and different substrates on the bond strength.

Strength and Thermal Properties of Hollow Foamed Concrete Blocks considering Various Parameters

Hot weather is one of the main problems the residential building construction field faces, especially in the southern hemisphere. Therefore, there is an increasing need to produce materials capable of reducing the high temperature impact. These materials should be characterized by thermal insulation properties without, though, their mechanical properties and load resistance being affected. In this research, cuboid and hexagonal hollow concrete blocks were produced from lightweight foam concrete with different hole shapes and a hole ratio of 30%. An analytical study was conducted for 8 models using the ANSYS v16 program, while the compression behavior and thermal performance of the selected models were studied. Ordinary Portland Cement (OPC), water, sand, and foaming agents were deployed in the production of foamed concrete. In addition to the use of admixtures, materials, such as Superplasticizer (SP), Class F Fly Ash (FA), and Silica Fume (SF), were also utilized. Moreover, the effect of the hole’s shape and the method of bonding were studied. The compressive strength of the concrete blocks, bond shear strength, thermal conductivity, and thermal resistance were tested. It was found that the cuboid shape of the hole block H7 was the most acceptable compared to the other shapes, with a compressive strength of 3.75 MPa, thermal conductivity of 0.149 W/m.k, and a bond shear strength of 0.157 MPa. At the same time, it was found that using bonding adhesive material gave the best results, with the cuboid blocks being compared to using mortar and mechanical bonding.

Recyclable polyurethane from castor oil based on dynamic disulfide bonds and multiple hydrogen bonds as adhesive and photothermal conversion materials

As an important polymer material, polyurethane brings convenience to daily life but also causes environmental problems, and the manufacturing of bio-based repairable, re-processable and sturdy materials can effectively reduce environmental pressure. Herein a low temperature recyclable polyurethane (PU) was developed with castor oil (CO) by combining isophorone diisocyanate (IPDI), dynamic disulfide bonds and hydrogen bonds. The castor oil-based PU showed impressive tensile strength (16.1MPa) remarkable elongation at break (1055.8%), and high bonding power (up to ~6MPa) with bonding wood chips. The dynamic disulfide bonds and hydrogen bonds imparted the bio-based PU with outstanding elastic recovery, impressive self-healing capability (up to ~90%), short relaxation time (5~6min at 180°C), favorable shape memory behavior, and multiple recyclability. By mixing different proportions of carbon nanotubes (CNTs), recyclable and stretchable conductive composites are realized. In addition, an integrated system of high-efficiency bio-based solar photovoltaic generator is demonstrated for simulating the ambient sunlight-heat-electricity conversion, which provides some guidance for the efficient use of solar energy.

Monomer in situ polymerization as topological sutures to achieve strong interfacial adhesion and long-term anti-mold of renewable adhesive

Integrated long-term anti-mold and high bonding capacity properties into renewable biomass adhesives hold significant importance for promoting the green and sustainable development of the wood industry, yet it remains an immense challenge. Drawing inspiration from the design of molecular suture materials, we successfully developed a series of innovative quaternary ammonium salt monomers (APM12) that polymerize in situ with glycidyl methacrylate (GMA) at the interface of bonded adherents. This process constructed molecular sutures on the molecular scale, forming a robust topological entanglement network between the adhesive and the wood substrate. Such a rational structure design allowed the modified soybean meal (SM) adhesive to present a boosted bonding strength and water resistance (2.08 and 1.05MPa). The stably riveting high-effect anti-germ platform imparted the protein adhesive with ultra-long mildew resistance of 150 days for liquid SM@GMA-APM12 adhesives, outperforming all the previously reported protein-based bio-adhesives. The implementation of the suture strategy through an in situ sutural interspersed crosslinking network provided a straightforward approach and offered a novel solution for creating renewable adhesives with multiple desirable properties. Moreover, this suture strategy can be applied to other interface strong adhesion and anti-bacterial materials comprised of polymer structure, such as hydrogel, organic coatings, and membrane, broadening its scope of applications.

Hydrogels of dialdehyde starch and gelatin cross-linked with potential application as tissue adhesives.

Invasive surgical methods are the current standard for hemostasis and wound closure. In recent years, injectable hydrogels prepared from natural biomacromolecules have shown promise as tissue adhesives to overcome their shortcomings due to their high hydrophilicity and biocompatibility, but the inherent properties of unmodified biomolecules remain a major challenge in their application. In this paper, a hydrogel (DS/Gel-CDH) with self-healing, injectable and adhesive functions was constructed by Schiff base crosslinking between carbonyl hydrazide modified gelatin (Gel-CDH) and dialdehyde starch (DS). The adhesion strength of the hydrogel (34.92 kPa) is much better than that of commercially available protein adhesives (17.44 kPa). In addition, Cytotoxicity and hemolysis tests showed that the hydrogel was non-cytotoxic (cell survival rate was 96.9 %) and could be used as biomaterial in contact with blood. The rats skin incision wound model further confirmed that this hydrogel can adhere to the wound and promote healing. H&E and MT staining showed no signs of toxicity in the tissue around the wound, and IL-6 and IL-1β staining showed no inflammatory reaction. It is proved that the hydrogel has good biocompatibility and degradability in vivo. The results indicate that the multifunctional the DS/Gel-CDH hydrogels are a promising and effective tissue adhesive material.

Analysis of Wear Mechanisms Under Cutting Parameters: Influence of Double Layer TiAlN/TiN PVD and TiCN/Al2O3 Chemical Vapor Deposition-Coated Tools on Milling of AISI D2 Steel

Tool selection is relevant because a wide variety of materials exhibit different machinability behaviors. Tool life during manufacturing is commonly associated with productivity. Insert developers have been using coatings on cutting tools to enhance their performance, with chemical vapor deposition (CVD) and physical vapor deposition (PVD) being the two most used techniques. This study analyzed the cutting tool wear mechanism by machining AISI D2 steel using two different inserts of TiAlN/TiN PVD and TiCN/Al2O3 CVD as layers deposited on a carbide substrate. The two inserts were tested at three different cutting speeds, namely, low, medium, and high; these values were below the data suggested by the supplier catalog. The flank wear and rake face were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). The adhesion material, edge deformation, and abrasion were the main wear mechanisms before catastrophic damage occurred at the three different cutting speeds in the PVD cutting tool. Nevertheless, increasing the cutting speed reduced the tool life from 84% to 61% at high values compared to the medium values of PVD and CVD, respectively, where the medium value resulted in a balance between the material removal rate and tool life. The wear mechanism of the CVD tool was BUE and chipping; nevertheless, its craters were larger than those of the PVD. Compared to those configured for PVD, the CVD insert demonstrated the ability to machine D2 steel at twice the cutting speed with a workpiece surface roughness of 0.3 µm, in contrast to a variation of 0.6 to 0.15 µm with the PVD tool.