Physical Interlocking Research Articles

Electrochemistry of Molybdenum Single Crystals and Thin Wires in Cyanide and Gold Cyanide Electrolytes

Thin wires of molybdenum coated with gold are used for space applications and the adhesion of the gold layer is decisive for their use. The surface morphology of the wires is determined by the manufacturing process and preferential orientation of single crystal surfaces is expected. In this work three different single crystal surfaces were studied together with a 20 μm molybdenum wire to elucidate the importance of surface morphology on the electrodeposition process for gold. Electrochemical impedance spectroscopy was used to study the molybdenum samples in the absence and presence of gold cyanide complexes. The results show large pseudocapacitance prior to gold deposition, indicating the presence of a thin molybdenum oxide film on the surface. Thus, the electrodeposition takes place on the surface oxide and is afflicted with a nucleation overpotential. The overpotential is only slightly dependent on the single crystal orientation, while it is more negative for the wire. The adhesion of gold on the flat single crystal surfaces is weak but marginally better on the wire. This clearly shows that strong chemical binding to the surface is absent and that other processes, such as physical interlocking of the gold layer is necessary for good adhesion.

Hierarchical interface design of jute fibers/polypropylene composites for enhanced interfacial and mechanical properties

Natural fiber reinforced plastics (NFRPs) represent a promising category of emerging materials for sustainable industrial development owing to their renewability, degradability, and lightweight. However, the polarity mismatch between the fibers and polymer matrices weakens the mechanical properties of NFRPs. To address this issue, a novel hierarchical interface design was proposed here through the co-modification of silane coupling agents (SCAs) and zinc oxide nanorods (ZnO NRs), which exhibits not only high efficiency but also low energy consumption and environmental friendliness. Specifically, the hierarchical interface design was demonstrated on jute fibers (JFs)/polypropylene (PP) composites, where the JFs/ZnO interfaces were chemically bonded through complexation, chelation, or coordination using various SCAs; meanwhile, the ZnO/PP interfaces were physically bonded by interlocking effect. The experimental testing results indicated the exceptional mechanical properties of modified JFs and their composites. The JFs modified with 3-glycidyloxypropyltrimethoxysilane (KH560) and ZnO NRs exhibited an increase of 34.3% and 55.8% in single-fiber tensile strength and tensile modulus, respectively, compared to sololy ZnO coated JFs, and also showed an augment of 30.8% in the interfacial shear strength with PP resin. Thus, the transverse and longitudinal tensile strength of JFs/PP composites with combined modification of KH560 and ZnO NRs were 19.2% and 46.5% higher than untreated ones. The interfacial enhancement mechanism was ascribed to the synergistic effect of chemical bonding and physical interlocking, as revealed by molecular dynamics simulation and observation of fracture morphologies. The findings offer a cost-effective solution for developing JFs/PP composites with superior interfacial and mechanical properties, thereby promoting the practical applications and value of NFRPs.

Enhancing the mechanical properties of basalt fiber/nylon 6 composites by surface roughening and hydrogen bonding interaction

AbstractInspired by the strong adhesion of mussels, basalt fibers (BFs) were modified with polydopamine and then composited with nylon 6. The effect of polydopamine content on the interfacial interactions and mechanical properties of the composites was investigated. In addition, silica nanoparticles were grown on the surface of polydopamine‐modified BFs to investigate the synergistic effect. The study revealed that the mechanical properties of the composites based on polydopamine‐modified BF were gradually enhanced with the increase of the dopamine coverage concentration, and gradually decreased after reaching the peak. 0.5 g/L concentration of dopamine solution modified BFs showed the best enhancement effect on nylon 6, and its tensile strength could reach 133.1 MPa, which was 28.5% higher than that of the unmodified composites. The tensile strength of the composites modified with both dopamine and silica nanoparticles reached 157 MPa, which was 51.7% higher than that of the unmodified composites. In addition, scanning electron microscope images of fracture sections confirmed the strong interfacial interaction between BF and PA6.Highlights The surface roughness of BF was increased by nano‐SiO2. Hydrogen bonding was formed between PDA and PA6. Physical interlock was formed between nano‐SiO2 and PA6. Tensile strength increased by 51.7% with both nano‐SiO2 and PDA. Stronger interfacial interaction leads to higher thermal stability.

Composites based on polymeric blends reinforced with TiO2 modified aramid fibers

AbstractThe paper presents a study on composites based on 50:50 (PP:LLPE‐g‐MA) reinforced with 0.5, 1, and 2 wt% aramid fibers unmodified/modified with TiO2, processed by melt compounding. Micronic aramid fibers were acetone washed to remove impurities and treated with Ti(IV)isopropoxide precursor via sol–gel method, adding microcellulose for TiO2 particle dimension control. Composites were hot‐pressed into 4 mm‐thick plates for sampling and 0.5 mm‐thick sheets for thermoforming. All composites were successfully thermoformed, fibers‐based samples showing improved thermoforming ability without wrinkling. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy dispersive X‐ray spectroscopy (EDS) analysis confirmed the formation of TiO2 particles on the fiber surface. Optical microscopy, SEM and FTIR analysis exhibit the fibers' strong embedment into the matrix due to physical interlocking, generating surface defect reduction. Water absorption decreased from 0.195% (control) to 0.075 and 0% for 1 TiO2 and 2 TiO2 samples, due to material compactization. Contact angles increased from 95.18° (Control) to 108° (1 TiO2) and 112.89° (2 TiO2). The highest flexural strength and modulus were exhibited by 1 TiO2 sample that increased by 44.88% and 47.6% compared to the control sample, due to higher intrinsic rigidity of fibers and TiO2 modifying surface rugosity and phase interaction. The impact strength of the control sample improved by 139% compared to PP due to brittleness reduction, 1 TiO2 by 209% compared to PP, 29% compared to the control sample. The results and excellent thermoformability recommend the materials for encapsulation of electronic/expensive parts in automotive or drone applications, offering viable, facile, rapid, and cost‐effective solutions to easily replace damaged parts.Highlights Aramid fibers were successfully modified using isopropoxide precursor; Strong embedment of fibers in the polymer diminishes crack propagation/damage; Improved impact and bending properties and water contact angle; The composites showed a high ability to thermoform into complex shapes; Potential to replace non‐reusable materials as encapsulation solutions.

Enhancing flexural strength of metakaolin-based geopolymer reinforced with different types of fibers

Geopolymers are considered as eco-friendly materials and are used as a cement replacement material. However, geopolymer applications are limited due to its low flexural strength. This work improves the flexural strength of geopolymers by using glass fiber (GF) and bamboo fiber (BF) as the reinforcing materials. Metakaolin (MK) is used as a geopolymer precursor. The mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) is used as the alkaline activator. The results show that the interface bond between the reinforced fibers and the geopolymer matrix influences the flexural strength of the composites more than the inherent strength of fibers. Although the inherent strength of BF is lower than that of GF, BF can improve the flexural strength of MK-geopolymer more effectively than GF. The flexural strengths of MK-geopolymer are enhanced by 1.9, 2.5, and 2.6 times when adding 1%, 3%, and 5% by volume of BF, respectively. The rough surface of BF promotes physical interlocking and bonding between BF and the MK-geopolymer matrix. As a result, the flexural and compressive strength of the MK-geopolymer is enhanced by reinforcing with BF. Conversely, GF exhibits poor bonding with the MK-geopolymer matrix. Consequently, the use of GF as the reinforcing material does not improve the flexural and compressive strength of the MK-geopolymer.

Analysis of adhesion characteristics of steel back plates and encapsulants for fire-proof BIPV modules

Recently, researchers are actively exploring the use of steel plates as replacements for the backs of building integrated photovoltaic (BIPV) modules to achieve improved workability, reduced weight, and enhanced maintainability. It is crucial to note that the adhesion between steel plates and encapsulants must match the high level observed between conventional backsheets and glass surfaces. In this study, we assessed the adhesion between steel plates and encapsulants and proposed a method to enhance adhesion to the level of existing materials, such as backsheets and glass, by improving the surface of the steel plates and the lamination process. When steel plates were laminated with ethylene vinyl acetate (EVA) encapsulant at 150 °C (as per the preset process), the peel force measured by the 180° peel test was significantly low at 0.045 N/mm. However, it increased nearly 40 times to 1.70 N/mm due to the formation of a structure capable of physical interlocking through surface treatment and an increase in the lamination temperature by 20 °C. Furthermore, we evaluated the adhesion performance of polyolefin elastomer (POE) encapsulant, which demonstrated high adhesion of over 6.0 N/mm, comparable to that between the currently used encapsulants and backsheets. When we examined the surface-treated sample using a confocal microscope and a secondary electron microscope (SEM), the surface-treated sample exhibited a considerably rough surface with a high Rku value of 5 compared to the untreated sample. These modules can maintain high outputs even when exposed to the external environment for extended periods with fire-resistant properties.

Bioadhesive microneedle patches for tissue sealing

AbstractSealing of soft tissues prevents leakage of gas and liquid, closes wounds, and promotes healing and is, therefore, of great significance in the clinical and medical fields. Although various formulations have been developed for reliable sealing of soft tissue, tradeoffs between adhesive properties, degradation profile, and tissue toxicity limit their clinical use. Hydrogel‐based adhesives, for example, are highly biocompatible but adhere very weakly to the tissue and degrade quickly, while oxidized cellulose patches are poorly absorbed and may cause healing complications postoperatively. Here, we present a novel strategy for tissue sealing based on bioadhesive microneedle patches that can spontaneously adhere to tissue surface through electrostatic interactions and swell within it. A series of microneedle patches made of pullulan, chitosan, Carbopol, poly (lactic‐co‐glycolic acid), and a Carbopol/chitosan combination were fabricated and characterized for their use in tissue sealing. The effect of microneedle composition on the fabrication process, physical and mechanical properties, in vitro cytotoxicity, and in vivo biocompatibility were examined. The needle structure enables microneedles to strongly fix onto various tissues via physical interlocking, while their adhesive properties improve staying time and sealing capabilities. The microneedle patch comprising Carbopol needles and chitosan as a second pedestal layer presented the best results in terms of sealing and adhesion, a consequence of the needle's swelling and adhesion features combined with the supportive chitosan base layer. Finally, single Carbopol/chitosan patches stopped intense liver bleeding in a rat model significantly quicker and with less blood loss compared with commercial oxidized cellulose patches. These microneedles can be considered a promising cost‐effective platform for adhering and sealing tissues as they can be applied quickly and painlessly, and require less trained medical staff and equipment.

Hydrocarbon-Based Composite Membrane Using LCP-Nonwoven Fabrics for Durable Proton Exchange Membrane Water Electrolysis.

A new hydrocarbon-based (HC) composite membrane was developed using liquid crystal polymer (LCP)-nonwoven fabrics for application in proton exchange membrane water electrolysis (PEMWE). A copolymer of sulfonated poly(arylene ether sulfone) with a sulfonation degree of 50 mol% (SPAES50) was utilized as an ionomer for the HC membranes and impregnated into the LCP-nonwoven fabrics without any surface treatment of the LCP. The physical interlocking structure between the SPAES50 and LCP-nonwoven fabrics was investigated, validating the outstanding mechanical properties and dimensional stability of the composite membrane in comparison to the pristine membrane. In addition, the through-plane proton conductivity of the composite membrane at 80 °C was only 15% lower than that of the pristine membrane because of the defect-free impregnation state, minimizing the decrease in the proton conductivity caused by the non-proton conductive LCP. During the electrochemical evaluation, the superior cell performance of the composite membrane was evident, with a current density of 5.41 A/cm2 at 1.9 V, compared to 4.65 A/cm2 for the pristine membrane, which can be attributed to the smaller membrane resistance of the composite membrane. From the results of the degradation rates, the prepared composite membrane also showed enhanced cell efficiency and durability during the PEMWE operations.

Porcupine-inspired microneedles coupled with an adhesive back patching as dressing for accelerating diabetic wound healing.

Diabetes chronic wound is a severe and frequently occurring medical issue in patients with diabetes that often leads to more serious complications. Microneedles (MNs) can be used for wound healing as they can effectively pierce the epidermis and inject drugs into the wound tissue. However, common MN patches cannot provide sufficient skin adhesion to prevent detachment from the wound area. Inspired by the barb hangnail microstructure of porcupine quills, a porcupine quill-like multilayer MN patch with an adhesive back patching for tissue adhesion and diabetic wound healing was designed. Sodium hyaluronate-modified CaO2 nanoparticles and metformin (hypoglycemic agent) were loaded into the polycaprolactone tips of MNs, endowing them with exceptional antibacterial ability and hypoglycemic effect. A flexible and adhesive back patching was formed by polyacrylamide-polydopamine/Cu2+ composite hydrogel, which ensures that the MN patches do not peel off from the application sites and reduce bacterial infection. The bioinspired multilayer structure of MN patches exhibits satisfactory mechanical and antibacterial properties, which is a potential multifunctional dressing platform for promoting wound healing. STATEMENT OF SIGNIFICANCE: The porcupine quill-like microneedles (MNs) with PAM-PDA/Cu2+ (PPC) composite hydrogel back patching have been fabricated, which can enhance the adhesion property of MNs to the skin through a physical interlock of multilayer MNs and chemical bonding of hydrogel patching. CaO2-HA NPs and metformin were loaded into the polycaprolactone tips of MNs, endowing them with the exceptional antibacterial ability and hypoglycemic effect, which could accelerate diabetic wound healing. As a safe and effective strategy in transdermal delivery of drugs, the as-fabricated flexible multilayer MN patch with good antibacterial, hypoglycemic, and biocompatibility has been used to promote the healing of diabetic wound by releasing oxygen and inhibiting inflammation at the wound site.

Roles of carbonated recycled fines and aggregates in hydration, microstructure and mechanical properties of concrete: A critical review

CO2 mineralisation by recycled concrete is a novel approach of carbon capture and utilisation to improve the sustainability of concrete products, which has attracted increasing attention in recent years. This paper presents a comprehensive review on carbonation mechanisms related to CO2 mineralisation and hydration, microstructure and multiscale mechanical properties of concrete containing carbonated recycled concrete fines and aggregates, with special focus on the chemistry-microstructure-property relationships. The carbonation kinetics of recycled fines in aqueous environment exhibit a typical particle size effect, while the high pozzolanic reactivity of carbonated recycled fines can facilitate the nucleation and stabilization of hydration gels and contribute to the rapid hydration of cement paste. Carbonated recycled aggregates are favourable in enhancing the micro-mechanical properties of interfacial transition zone in concrete through the synergic effects of physical interlocking and chemical bonding. Compared to concrete with plain recycled aggregates, up to 33.0%, 12.1% and 28.7% rises in compressive, splitting and flexural strengths of concrete can be achieved under 100% replacement of carbonated recycled aggregates. Due to the Stefan effect, concrete with carbonated recycled aggregates has higher dynamic peak stress but lower strain-rate sensitivity of elastic modulus than concrete with plain recycled aggregates. The global CO2 mitigation capacity of recycled concrete varies from region to region and thus reasonable transportation network and high-efficient carbonation process are essential to ensure a balance between the environmental and economic benefits. This review summarises the recent advances in the field and discusses some future research opportunities to develop low-carbon concrete with recycled concrete as a carbon sink.

Enhanced the bonding reliability of titanium alloy and CFRTP via interfacial multiple modification: Synergy of physical interlocking and chemical interaction

A novel multiple modification approach including laser texturing, micro-arc oxidation process and silane coupling agent treatment was proposed to optimize the bonding interface. Firstly, laser texturing was fabricated to promote the mechanical interlocking. Secondly, the micro-arc oxidation porous structure was designed to modify its physical structure and chemical states. This promoted the interfacial mechanical interlocking in dual scales including texturing and porous structures. Moreover, the new chemical bonds such as Ti-C and Ti-O were generated at the interface. The bonding strength of TC4/CFRTP was enhanced from 10.23 MPa to 23.41 MPa. Besides, more hydroxyl groups (–OH) were adsorbed inside the optimized structure, and the hydrogen bonds were successfully induced by silane coupling film via the final step. This further enhanced the bonding strength to the maximum of 27.22 MPa. Therefore, the multiple modification approach realized the comprehensive enhancement of mechanical interlocking, chemical bonding and functional groups interaction, which enhanced the bonding reliability by 166% than pretreated case. These results benefit future research in the process optimization to improve the reliability of metal-CFRTP bonding structures.

Self-healing bottlebrush polymer networks enabled via a side-chain interlocking design.

Exploring novel healing mechanisms is a constant impetus for the development of self-healing materials. Herein, we find that side-chain interlocking of bottlebrush polymers can form a dynamic network and thereby serve as a driving force for the self-healing process of the materials. Molecular dynamics simulation indicates that the interlocking is formed by the interpenetration between the long side chains of adjacent molecules and stabilized by van der Waals interactions and molecular entanglements of side chains. The interlocking can be tailored by changing the length and density of the side chains through atom transfer radical polymerization. As a result, the optimized bottlebrush polymer shows a healing efficiency of up to 100%. Unlike chemical interactions, side-chain interlocking eliminates the introduction of specific chemical groups. Therefore, bottlebrush polymers can even self-heal under harsh aqueous conditions, including acid and alkali solutions. Moreover, the highly dynamic side-chain interlocking enables bottlebrush polymers to efficiently dissipate vibration energy, and thus they can be used as damping materials. Collectively, side-chain interlocking expands the scope of physical interactions in self-healing materials and hews out a versatile way for polymers to accomplish self-healing capability in various environments.

Degradable Bioadhesives Based on Star PEG-PLA Hydrogels for Soft Tissue Applications.

Tissue adhesives are interesting materials for wound treatment as they present numerous advantages compared to traditional methods of wound closure such as suturing and stapling. Nowadays, fibrin and cyanoacrylate glues are the most widespread commercial biomedical adhesives, but these systems display some drawbacks. In this study, degradable bioadhesives based on PEG-PLA star-shaped hydrogels are designed. Acrylate, methacrylate, and catechol functional copolymers are synthesized and used to design various bioadhesive hydrogels. Various types of mechanisms responsible for adhesion are investigated (physical entanglement and interlocking, physical interactions, chemical bonds), and the adhesive properties of the different systems are first studied on a gelatin model and compared to fibrin and cyanoacrylate references. Hydrogels based on acrylate and methacrylate reached adhesion strength close to cyanoacrylate (332 kPa) with values of 343 and 293 kPa, respectively, whereas catechol systems displayed higher values (11 and 19 kPa) compared to fibrin glue (7 kPa). Bioadhesives were then tested on mouse skin and human cadaveric colonic tissue. The results on mouse skin confirmed the potential of acrylate and methacrylate gels with adhesion strength close to commercial glues (15-30 kPa), whereas none of the systems led to high levels of adhesion on the colon. These data confirm that we designed a family of degradable bioadhesives with adhesion strength in the range of commercial glues. The low level of cytotoxicity of these materials is also demonstrated and confirm the potential of these hydrogels to be used as surgical adhesives.

Study on the dense structure and properties of cement-stabilized coral aggregates

The performance of cement stabilized coral aggregates semi-rigid base of pavement with coral reef limestone fragments and biological debris as the main materials is essential in the current reef engineering constructions. The performance of inorganic mixtures such as cement-stabilized coral aggregates mainly depends on the packing state of aggregates and the interfacial bonding among each component. Via digital image analysis theory, a simulation model of the dense packing of particles method was established, considering the influence of arbitrary particles shape distribution, upper limit of particles size, and aggregates gradation. The influencing mechanism of different factors on the packing state was revealed. It was found that the dense packing of coral aggregates is a strong suspension dense structure which did not form the skeleton structure. The strengthening mechanism of the coral particle-coated cement slurry was studied through the experimental analysis of the pore structure of coral rocks and debris particles and the crushing strength of particle-coated cement slurry, combined with the microhardness test of the cement- coral particle interface and the analysis of hydration products. The physicochemical excitation mechanism of hydration products densification，“physical interlocking” and “micro pump” effect at the interface of the cement-coral particle was revealed. Furthermore, based on the macroscopic mechanical properties of cement stabilized coral aggregates, the optimal design ratio of coral aggregates with upper limit particle size of 53mm, fine aggregates content of 45% and cement content of 8% was proposed. The findings of this study can provide a reference for the design and application of cement stabilized coral aggregates semi-rigid pavement base.

The impact of medication on osseointegration and implant anchorage in bone determined using removal torque—A review

Permanently anchored metal implants are frequently used in dental, craniomaxillofacial, and orthopaedic rehabilitation. The success of such therapies is owed to the phenomenon of osseointegration—the direct connection between the living bone and the implant. The extent of biomechanical anchorage (i.e., physical interlocking between the implant and bone) can be assessed with removal torque (RTQ) measurement. Implant anchorage is strongly influenced by underlying bone quality, involving physicochemical and biological properties such as composition and structural organisation of extracellular matrix, extent of micro-damage, and bone turnover. In this review, we evaluated the impact of various pharmacological agents on osseointegration, from animal experiments conducting RTQ measurements. In addition to substances whose antiresorptive and/or anti-catabolic effects on bone are well-documented (e.g., alendronate, zoledronate, ibandronate, raloxifene, human parathyroid hormone, odanacatib, and the sclerostin monoclonal antibody), positive effects on RTQ have been reported for substances that do not primarily target bone (e.g., aminoguanidine, insulin, losartan, simvastatin, bone morphogenetic protein, alpha-tocopherol, and the combination of silk fibroin powder and platelet-rich fibrin). On the contrary, several substances (e.g., prednisolone, cyclosporin A, cisplatin, and enamel matrix derivative) tend to adversely impact RTQ. While morphometric parameters such as bone-implant contact appear to influence the biomechanical anchorage, increased or decreased RTQ is not always accompanied by corresponding fluctuations in bone-implant contact. This further confirms that factors such as bone quality underpin biomechanical anchorage of metal implants. Several fundamental questions on drug metabolism and bioavailability, drug dosage, animal-to-human translation, and the consequences of treatment interruption remain yet unanswered.

Shear thickening in dense suspensions driven by particle interlocking

The processing of dense suspensions is a crucial step in many industries including mining; the production of ceramics; and the manufacture of pharmaceuticals. It is widely reported that these suspensions exhibit nonlinear behaviours such as shear thinning and thickening, with particle surface contacts recently being accepted as a primary culprit in the latter. In light of this, the modelling community have started to explore the role of particle surface tribology, predominantly by incorporating Coulombic friction models borrowed from the field of dry granular matter. Full details of the interactions between particle surfaces remain unclear, however, and it is suggested that physical interlocking of particle asperities may be key. Here, we use particle-based simulations to explore explicitly the effect of interlocking on the rheology of dense suspensions of micron-sized solids in a Newtonian fluid. Our simplified model recovers shear thinning, thickening and jamming phenomena commonly seen in experiments.

Ultra-sounding out a technique that sticks.

Ultrasound can be used to promote the physical interlocking of adhesives and tissues.

Criticality of microstructural evolution at an early age on the buildability of an accelerated 3D printable concrete

The buildability of a 3D printed concrete structure is influenced by the layer compression during printing, which in turn is governed by the rheological and early age mechanical properties of the mix. The study aims at understanding the effect of alkali-free aluminium sulphate-based accelerator on the microstructural evolution, which affects the macrostructural behaviour governing buildability of the structure. The effect of accelerator on hydration, phase composition, location and arrangement of ettringite, and porosity evolution of two paste systems with and without viscosity modifying admixture and superplasticizer is observed at initial hours. Further, fresh properties, yield stress evolution, and mechanical strength at early and later ages of the printable mix is evaluated. The squeeze flow test, which simulates the physical process of printing, is performed to understand the rheological characteristics of the mix under compressive loading in the initial hours. It is concluded that the precipitation of ettringite in large quantities at the initial hours controls the rheological and mechanical behaviour of the mix. The total ettringite formed increases for accelerated paste system at 30 min compared to the paste without accelerator. The ettringite is located at surfaces of clinker and interstitial spaces, with the crystals interlocked physically with each other. The squeeze flow test further suggests that the flow hardening increases tremendously on increasing the accelerator dosage due to an increase in solid volume fraction of ettringite and the resultant physical interlocking. Finally, a theoretical model is proposed considering the significance of ettringite interlocking and microstructure densification under compression on the plastic flow hardening for accelerated mixes.

Wet-adhesive materials of oral and maxillofacial region: From design to application

Oral and maxillofacial diseases are a group of high-incidence disorders that affect people's life quality to a great extent, while the wet and highly movable environment of the related regions brings challenges to traditional therapies. Faced with the obstacles of insufficient adhesive strength and ensuing short drug retention time, conventional oral therapeutic agents often have difficulty in achieving their desired efficacy. Oral and maxillofacial wet-adhesive materials have the advantages of excellent wet environment retention, internal stability, plasticity, and clinical potential, thus have become a significant research direction in the field of oral related disorders healing. In the past decade, the development of oral adhesive materials with good wet adhesion has accelerated based on the chemical molecular interaction, physical interlocking, and biological adhesion mechanisms, including biomimetic-inspired materials, naturally derived polymer–based materials and adhesive electrospun fiber films. These fancy wet-adhesive materials can be used for oral mucosal drug delivery, oral vaccination, wound healing, and bone defects treatments. Despite their numerous novel applications, wet-adhesive materials in stomatology still face unresolved challenges from material and biological aspects. Here, advances in designs of oral and maxillofacial wet-adhesive materials are reviewed in terms of design backgrounds, attachment mechanisms, and common classifications. Recent demonstrations of wet-adhesive materials for oral and maxillofacial region medical applications from drug delivery to multifunctional tissue treatments are presented. To conclude, current challenges and prospects on potential applications of oral and maxillofacial wet-adhesive materials are also briefly discussed.

Partial Biodegradable Blend with High Stability against Biodegradation for Fused Deposition Modeling.

This research presents a partial biodegradable polymeric blend aimed for large-scale fused deposition modeling (FDM). The literature reports partial biodegradable blends with high contents of fossil fuel-based polymers (>20%) that make them unfriendly to the ecosystem. Furthermore, the reported polymer systems neither present good mechanical strength nor have been investigated in vulnerable environments that results in biodegradation. This research, as a continuity of previous work, presents the stability against biodegradability of a partial biodegradable blend prepared with polylactic acid (PLA) and polypropylene (PP). The blend is designed with intended excess physical interlocking and sufficient chemical grafting, which has only been investigated for thermal and hydrolytic degradation before by the same authors. The research presents, for the first time, ANOVA analysis for the statistical evaluation of endurance against biodegradability. The statistical results are complemented with thermochemical and visual analysis. Fourier transform infrared spectroscopy (FTIR) determines the signs of intermolecular interactions that are further confirmed by differential scanning calorimetry (DSC). The thermochemical interactions observed in FTIR and DSC are validated with thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) is also used as a visual technique to affirm the physical interlocking. It is concluded that the blend exhibits high stability against soil biodegradation in terms of high mechanical strength and high mass retention percentage.