Hot Melt Research Articles

An Detailed Overview on Mouth Dissolving Film

The present review aims to enlighten about a potential dosage form that is mouth dissolving films. Mouth dissolving film is a rapidly dissolving dosage form that dissolves in the mouth within a few seconds without the intake of water and is mainly used for pediatric and geriatric patients due to its flexibility and patient compliance. It is a potential dosage form for drugs having high metabolism and low bioavailability. Solvent casting, hot melt extrusion, solid dispersion, semisolid casting, rolling, and other processes can all be used to create mouth dissolving film, but solvent casting is the most popular due to its consistency and superior physical properties. Mouth dissolving film is evaluated for the following parameters like physical parameters and chemical parameters. The review sums up information on drug delivery by mouth dissolving films as a promising dosage form for delivering drugs to children and elderly patients, as well as information on its formulation considerations, preparation process, and evaluation criteria.
 Keywords: Mouth dissolving film, Buccal film, Improved patient compliance, Standard composition, Method of preparation, Evaluation

A versatile hot melt centrifugal spinning apparatus for thermoplastic microfibres production

The centrifugal spinning (CS) method could address common issues such as low production rate and high energy consumption in the industry of nonwoven textile fabrication. Similarly to cotton candy production, the high-speed rotating reservoir extrudes melt or solvent-based polymer from orifices to produce fibres. Using polymer melt avoids solvent elimination and toxicity, but the process is more difficult. Thus, a versatile lab-scale hot melt spinneret with the ability to pour pellets inside continuously to expand our knowledge of the CS method and investigating different extrusion geometries such as nozzlefree is developed. Among the controllable parameters are, the spinneret heating temperature (up to 300°C), its two interchangeable 3D printer nozzles. An Arduino code is used to stabilize the temperature. The system performance is investigated with polypropylene and polylactide. The results show that fibres under 15 μm in diameter are produced. This work is licensed under CC BY-NC 4.0. To view a copy of this license, visithttp://creativecommons.org/licenses/by-nc/4.0/.

Personalization of Complex Vaginal Inserts of Ethylene Vinyl Acetate via 3D‐Printing

AbstractEthylene vinyl acetate (EVA) with a vinyl acetate (VA) content of 28 wt.% (EVA28) is frequently used in vaginal inserts and subcutaneous implants due to its biocompatibility and drug‐releasing properties. Traditionally being processed via hot melt extrusion, its processibility via filament‐based 3D‐printing was reported to be impossible. Consequently, no applicable customization concepts for vaginal inserts exist. For the first time, the fabrication of 3D‐printed vaginal inserts (urethra pessaries) of EVA28 is demonstrated by optimizing its viscosity, employing 3D‐printer adaptations, and carefully selecting printing parameters. The infill pattern of fully filled mono‐material pessaries (determining the number and orientation of weld lines) significantly affects the in vitro release of the model drug progesterone (P4), while other critical parameters (the pessary's mechanical properties and appearance) remain unaffected. Weld lines act as diffusion barriers for dissolved P4 molecules. Hence, a high number of weld lines to be crossed reduces the overall P4 diffusivity in EVA28, decreasing the P4 release rate. To further control the P4 release, innovative multi‐material pessary designs (additionally comprising EVA with a VA content of 9 wt.% that is also used in vaginal inserts) allow to tailor the in vitro drug release and the mechanics individually. Thereby, this work highly improves the mechanistic understanding on drug release modifications from 3D‐printed non‐biodegradable devices. The findings build the basis for the first application of customized vaginal inserts, as they are based on polymers used in corresponding marketed products for more than 20 years.

Solid amorphous formulations for enhancing solubility and inhibiting Erlotinib crystallization during gastric-to-intestinal transfer

The objective of this study was to improve the solubility and inhibit the crystallisation during the gastric-to-intestinal transfer of Erlotinib (ERL), a small molecule kinase inhibitor (smKI) compound class, which is classified as class II drug in the Biopharmaceutical Classification System (BCS). A screening approach combining different parameters (solubility in aqueous media, inhibitory effect of drug crystallisation from supersaturated drug solutions) was applied to selected polymers for the development of solid amorphous dispersions of ERL. ERL solid amorphous dispersions formulations were then prepared with 3 different polymers (Soluplus®, HPMC-AS-L, HPMC-AS-H) at a fixed drug: polymer ratio (1:4) by two different production methods (spray drying and hot melt extrusion). The spray-dried particles and cryo-milled extrudates were characterized by thermal properties, shape and particle size, solubility and dissolution behavior in aqueous media. The influence of the manufacturing process on these solid characteristics was also identified during this study. Based on the obtained results, it is concluded that the cryo-milled extrudates of HPMC-AS-L displayed better performance (enhanced solubility, reduced ERL crystallization during the simulated gastric-to-intestinal transfer) and represents a promising amorphous solid dispersion formulation for oral administration of ERL.

Carbonized Oligomer‐Like Dots: Efficient Persistent Room‐Temperature Phosphorescent Materials with Superior Mechanical Strength

AbstractThe development of persistent room‐temperature phosphorescence (pRTP) materials has been rapid in recent years; however, producing pRTP materials with high luminescent characteristics, mechanical strength, and processability is a difficult issue. Herein, a new class of pRTP materials named carbonized oligomer‐like dots (CODs) is reported, which have injection molding capacity and high mechanical strength in castings. The luminescence and mechanical properties of the CODs (PN1‐PN4) may be altered by altering the quantity of phosphoric acid and diethylenetriamine using a microwave‐assisted heating technique. Among them, the longest lifetime of PN3 attains 1.21 s with an afterglow time of over 20 s, while the maximum Young's modulus of PN1 is up to 2.36 GPa. The existence of n–π* transition is beneficial to promote the intersystem crossing, and multiple hydrogen bonds in the aggregates play a crucial role in the formation of pRTP with mechanical and hot melt adhesive properties. This study may pave the way for the development of pRTP materials with superior mechanical strength in the fields of information encryption and flexible displays.

Can Continuous Manufacturing of Topical Semisolids by Hot Melt Extrusion Soon Be a Reality?

For more than five decades, pharmaceutical manufacturers have been relying heavily on batch manufacturing that is a sequential, multistep, laborious, and time-consuming process. However, late advances in manufacturing technologies have prompted manufacturers to consider continuous manufacturing (CM) is a feasible manufacturing process that encompasses fewer steps and is less tedious and quick. Global regulatory agencies are taking a proactive role to facilitate pharmaceutical industries to adopt CM that assures product quality by employing robust manufacturing technologies encountering fewer interruptions, thereby substantially reducing product failures and recalls. However, adopting innovative CM is known to pose technical and regulatory challenges. Hot melt extrusion (HME) is one such state-of-the-art enabling technology that facilitates CM of diverse pharmaceutical dosage forms, including topical semisolids. Efforts have been made to continuously manufacture semisolids by HME integrating the principles of Quality by Design (QbD) and Quality Risk Management (QRM) and deploying Process Analytical Technologies (PAT) tools. Attempts have been made to systematically elucidate the effect of critical material attributes (CMA) and critical process parameters (CPP) on product critical quality attributes (CQA) and Quality Target Product Profiles (QTPP) deploying PAT tools. The article critically reviews the feasibility of one of the enabling technologies such as HME in CM of topical semisolids. The review highlights the benefits of the CM process and challenges ahead to implement the technology to topical semisolids. Once the CM of semisolids adopting melt extrusion integrated with PAT tools becomes a reality, the process can be extended to manufacture sterile semisolids that usually involve more critical processing steps.

Fill level measurement of low-permittivity material using an M-sequence UWB radar

AbstractDue to increasingly complex and automated manufacturing processes, the demands on the control parameters of these processes are also increasing. One parameter is the fill quantity of, e.g., liquids in production plants, whose precise determination is of ever-growing importance. Up to now, the exact level of determination under difficult conditions, such as high ambient temperatures, has been a particular challenge. This paper demonstrates a novel method by which an M-sequence UWB radar can determine levels of low-permittivity materials in small metal containers. For this purpose, hot melt is used as an example. Thus, the influence of large temperature differences on the long-term stability of level measurement can also be investigated. The measurements show that the level of hot melt can be measured to be long-term stable with an accuracy of better than 3 mm. Furthermore, the precise determination of the empty state is highly important for many applications. For this reason, this paper shows a method for determining the empty state without complex calibration procedures. For the empty level indication, an accuracy of up to 0.5 mm could be achieved for molten hot glue and 3% of the tank volume, independent of the shape or aggregate state of the medium.

DESIGN, OPTIMIZATION, AND CHARACTERIZATION OF A NOVEL AMORPHOUS SOLID DISPERSION FORMULATION FOR ENHANCEMENT OF SOLUBILITY AND DISSOLUTION OF TICAGRELOR

Objective: The study aims to enhance the solubility and dissolution of ticagrelor by formulating an amorphous solid dispersion using the hot melt extrusion technique. Methods: Solubility of ticagrelor is very limited in water and buffers of pH 1.2 to 6.8, which is one of the prime reasons for its low oral bioavailability. Amorphous solid dispersions were prepared using the Hot Melt Extrusion technique using different polymers, plasticizers, and surfactants. The formulation is optimized based on the level of polymer in the formulation. The final formulation of Ticagrelor Amorphous Solid Dispersion is made with a drug-polymer ratio of 1:3, keeping the plasticizer level at 10% of the polymer along with a surfactant Sodium Lauryl Sulfate. Results: The formulation showed an increase in solubility of 193.95-times in water, 50.71-times in 0.1 N HCl, 332.74-times in pH 4.5 acetate buffer, and 85.20-times in pH 6.8 phosphate buffer as compared to the pure drug. The drug release of the final formulation was found to be 70.0±4.4%, 55.4±1.1%, 35.5±2.1%, and 30.0±0.8% at 90 min, while the reference product showed a release of 9.4±1.1%, 20.7±0.5%, 8.4±0.3%, and 7.8±0.2% at 90 min in water, 0.1 N HCl, pH 4.5 acetate buffer and pH 6.8 Phosphate Buffer respectively. The drug release of the final formulation was found to be 99.1±3.8% at 60 min in 0.2% w/v Polysorbate-80 in water. Conclusion: In the present study, the amorphous solid dispersion of the poorly-soluble drug ticagrelor was successfully prepared. The polymer, Plasdone S630, is considered the most suitable with ticagrelor for formulating amorphous solid dispersion using Hot Melt Extrusion technology to increase the solubility and dissolution of the drug.

Design of interface dynamic cross-linked hybrid network with highly improved mechanical, recycling and adhesive performance

Engineering interface dynamic crosslinking is particularly favorable for nanocomposite to acquire intriguing properties such as energy dissipation, recyclability and adhesion, yet it still remains a formidable task. Herein, we report a robust and recyclable nanocomposite hot melt adhesives (HMAs) enabled by employing noncovalent interactions at the interface between core–shell structured silica nanoparticles (T-SiO2 NPs) and carboxylated ethylene vinyl acetate copolymer (EVA-COOH). Through elaborate architecture by hydrogen bonds and Fe-based coordination bonds assembly of interface crosslinking network, the resultant hybrid network exhibits excellent mechanical properties, with tensile strength of 11.34 MPa, modulus of 2.64 MPa and toughness of 104.4 MJ m−3, which are 2.89 times, 1.77 times and 1.80 times that of the neat EVA, respectively. Furthermore, due to the dynamic nature of the network, its mechanical properties could be well maintained (∼100 %) even after multiple generations of recycling. More strikingly, the as-prepared HMAs displayed an outstanding ability to bond diverse substrates tightly. In addition, stable adhesion performance is realized on the aluminum (Al) surface under air and harsh conditions. This inorganic–organic interface crosslinking strategy shows great significance for fabricating low-cost and environmentally adaptive functional materials.

Polymeric hollow fiber heat transfer surface for heat exchanger

Polymeric heat transfer surfaces (HTS) offer numerous advantages, such as flexibility, fouling resistance, corrosion and chemical resistance, and good recyclability. Moreover, polymeric materials have a lower carbon footprint than commonly used metal materials in the heat exchanger industry, making them an environmentally-friendly choice. In this study, we propose a novel nonwoven fabric technology for the fabrication of HTS. This technology enables the production of three-dimensional objects with precisely separated hollow polymeric fibers, resulting in highly efficient polymeric heat exchangers (HE). The fabrication process is based on the hot melt technique, where the polymeric melt (helmitin 42048) is perpendicularly applied to the longitudinal hollow fibers (polyamide 612). To evaluate the performance of the developed HTS, polymeric HE was produced and compared with a conventional aluminum HE, which served as a heater core in a gas-to-liquid application. The polymeric HE exhibited similar pressure losses on the liquid side and slightly higher losses on the gas side while achieving comparable thermal performance. For a liquid flow rate of 150 l·h−1 and an air velocity of 4 m·s−1, the polymeric HE reached a maximum thermal performance of almost 0.8 kW. The results demonstrate the functionality of the developed HTS technology and its potential as an advancement in heat transfer processes. The utilization of polymeric HTS in heat exchangers shows promising prospects for enhanced thermal performance, paving the way for sustainable and efficient heat transfer applications.

Study and Characterization of Polyvinyl Alcohol-Based Formulations for 3D Printlets Obtained via Fused Deposition Modeling.

Three-dimensional (3D) printing has emerged as a new promising technique for the production of personalized dosage forms and medical devices. Polyvinyl alcohol is prominently used as a source material to produce 3D-printed medicines via fused deposition modeling (FDM)-a technology that combines hot melt extrusion and 3D printing. A preliminary screening of three grades of PVA indicated that partially hydrolyzed PVA with a molecular weight (MW) of 31,000-50,000 and plasticized with sorbitol was most suitable for 3D printing. Paracetamol was used as a model drug. The materials and the produced filaments were characterized by X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The complex viscosity (η*) of the polymer melts was determined as a function of the angular frequency (ω) at the printing temperature to assess their printability. Three-dimensional printlets with a 40% infill exhibited an immediate release of the API, while tablets with a higher infill were prone to a prolonged release regardless of the filament drug loading. A factorial design was used to give more insight into the influence of the drug-loading of the filaments and the tablet infill as independent variables on the production of 3D printlets. The Pareto chart confirmed that the infill had a statistically significant effect on the dissolution rate after 45 min, which was chosen as the response variable.

Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica

Abstract Precise constraints on the compositions of melts generated by anatexis under ultrahigh temperature (UHT) conditions are critical for understanding processes of partial melting and differentiation of the Earth’s crust. Here we reveal geochemical and physical signatures of anatectic melts preserved as nanogranitoids (i.e. crystalized melt inclusions) within sapphirine-bearing UHT metapelitic granulites from the Mather Peninsula, East Antarctica. Their coexistence with high−Al orthopyroxene as inclusions in garnets strongly suggests that the investigated melts were at least partially UHT in origin. The nanogranitoids are enriched in SiO2 (69.9–75.6 wt.%), strongly peraluminous (ASI values = 1.2–1.6) and potassic to ultrapotassic (Na2O + K2O = 7.1–9.5 wt.%, K/Na = 2.2–9.3). When compared to the granulitic restite, the melts are enriched in Li, Cs, Rb, Ta, Sm, Nd, Zr, U and Pb, and depleted in Ce, Th, Ba, Sr and Nb. Their geochemical characteristics are consistent with biotite−dehydration melting in the absence of plagioclase. Our calculation results indicate that these hot crustal melts have low densities of 2.47 ± 0.07 g/cm3, low viscosities of 104.9 ± 1.2 Pa·s and high heat production values of ∼2.8 μW/m3. Therefore, such melts are mobile and susceptible to be extracted from the source, and consequently their flow and removal from the deep crust may greatly affect the chemical and thermal structure of the continental crust. Secondary C − O − H fluid inclusions within garnet and orthopyroxene have also been detected. These inclusions contain magnesite, pyrophyllite, corundum, with or without residual CO2. The minerals within the fluid inclusions are interpreted as stepdaughter minerals, which were produced by the reaction of the fluid with its host. The metamorphic timing of the investigated rocks is still a matter of debate. Zircon U–Pb dating results obtained in this study suggest that the metapelitic granulites may have undergone two separated thermal events at ∼1000 and ∼530 Ma, respectively. The presence of fluid inclusions indicates that fluid infiltration and Pan–African reworking may have played an important role in obscuring chronological information of the early thermal scenario in poly-metamorphic terranes.

Hot melt extrusion with low-temperature deposition-coupling control improves the 3D printing accuracy of gelatin/fish pulp recombinant products

The flow properties of original materials directly affect the shape customization of 3D printing. In order to improve the molding quality, the 3D printing equipment was developed, which was characterized by a variable pressure and temperature extrusion unit, a numerical control transmission unit, an extrusion refrigeration unit, and a control box. The optimal pretreatment condition of sturgeon skin was 0.015 M phosphoric acid with higher gel strength (739.27 g), which could be a good substitute for commercial gelatin. The 7% gelatin/fish pulp reconstituted system could exhibit optimum printing properties through an improved 3D printer. The reconstituted system displayed a smoother printing process and superior accuracy during the process of 3D printing, and showed higher apparent viscosity and modulus during the process of cooling and molding. Additionally, the network structure of 3D printing products of reconstituted the gelatin/fish pulp was denser, which showed higher water holding capacity (89.03%), higher hardness (775.64 g), and constant elasticity (0.9853).

A review on orodispersible drug delivery system

The future of drug delivery holds great promise for orally dispersible dose formulations, which make application simple since no water requirement as compared to conventional solid dosage forms which requires significant volumes of fluids for administration. The objective for development of ODF provides a substitute for pills, syrups, and tablets in treating vomiting as well as nausea, particularly in children. On the basis of transdermal patch delivery system, a novel oral films drug delivery has been introduced. Fast dissolving films disintegrates quickly when come in contact with salivary secretion in the oral mucosa and released the drug fast approximately within 3 mins. ODFs are of different types, like sustained or controlled release, oral patches and fast dissolving films. They can be manufactured using a variety of method including solvent and semi solid casting, hot melt and solid dispersion extrusion, spray drying and rolling. Among them solvent casting method is the most employed method. ODFs comprises of active ingredient, polymer, plasticizer and additives like surfactants, sweetening and coloring agents. ODFs preparation requires hydrophilic polymer which provides quick dissolution in the oral cavity. Hydrophilic polymer act as base for ODFs formulation as they impart mouth feel and mechanical properties of the ODFs also dependent of polymer type. Oral thin-film provide fast drug dissolution precise dosage in a portable, safe, and handy manner that doesn't required water or any special equipment. This review article comprises of different methods for ODFs preparations, ODFs ingredients, ODFs benefits and drawbacks and their packaging.

A review on orodispersible drug delivery system

The future of drug delivery holds great promise for orally dispersible dose formulations, which make application simple since no water requirement as compared to conventional solid dosage forms which requires significant volumes of fluids for administration. The objective for development of ODF provides a substitute for pills, syrups, and tablets in treating vomiting as well as nausea, particularly in children. On the basis of transdermal patch delivery system, a novel oral films drug delivery has been introduced. Fast dissolving films disintegrates quickly when come in contact with salivary secretion in the oral mucosa and released the drug fast approximately within 3 mins. ODFs are of different types, like sustained or controlled release, oral patches and fast dissolving films. They can be manufactured using a variety of method including solvent and semi solid casting, hot melt and solid dispersion extrusion, spray drying and rolling. Among them solvent casting method is the most employed method. ODFs comprises of active ingredient, polymer, plasticizer and additives like surfactants, sweetening and coloring agents. ODFs preparation requires hydrophilic polymer which provides quick dissolution in the oral cavity. Hydrophilic polymer act as base for ODFs formulation as they impart mouth feel and mechanical properties of the ODFs also dependent of polymer type. Oral thin-film provide fast drug dissolution precise dosage in a portable, safe, and handy manner that doesn't required water or any special equipment. This review article comprises of different methods for ODFs preparations, ODFs ingredients, ODFs benefits and drawbacks and their packaging.

Investigating the Innovation and Application of Jackson Pollock's (Drip Painting) Elements in Fashion Design

As a unique cultural carrier, clothing always reflects people's way of life and aesthetic concepts. With the continuous development of global economic integration and the mutual integration of multiculturalism, people's aesthetic needs for clothing are becoming increasingly diversified. The painting process of Jackson Pollock's “drip painting” is carried out in an unconscious mental state, which is very subjective and random. It uses a combination of lines, colors, and shapes to portray nature in his imagination. At the same time, he also pays great attention to applying comprehensive materials. His creative idea can also be used in clothing, which can enrich the artistic language of clothing and improve the artistry of clothing. This study applies acrylic and colors hot melt adhesive to clothing fabric in a way similar to Pollock's "drip painting" through practical research to test its fluidity and coloring effect on the fabric and the layering of lines. The experimental results conclude that the adaptability of hot melt adhesive stick and canvas fabric is very high, and its fluidity and stability can confirm the feasibility of applying it to clothing design. However, the performance effect of acrylic pigment in this practical research is not ideal. This study found that atypical clothing materials can make clothing more abstract and play a positive role in the personalized expression of clothing.

The Use of Hot Melt Extrusion to Prepare a Solid Dispersion of Ibuprofen in a Polymer Matrix.

In this work, we report the use of the hot melt extrusion method in harsh extrusion conditions, i.e., screw rotation speed of 250 rpm, temperature above 100 °C, and two mixing zones, in order to obtain an amorphous dispersion of an active pharmaceutical ingredient (API) that is sparingly soluble in water. As a polymer matrix Eudragit EPO (E-EPO) and as an API ibuprofen (IBU) were used in the research. In addition, the plasticizer Compritol 888 ATO (COM) was tested as a factor potentially improving processing parameters and modifying the IBU release profile. In studies, 25% by weight of IBU, 10% of COM and various extrusion temperatures, i.e., 90, 100, 120, 130, and 140 °C, were used. Hot melt extrusion (HME) temperatures were selected based on the glass transition temperature of the polymer matrix (Tg = 42 °C) and the melting points of IBU (Tm = 76 °C) and COM (Tm = 73 °C), which were tested by differential scanning calorimetry (DSC). The thermal stability of the tested compounds, determined on the basis of measurements carried out by thermogravimetric analysis (TGA), was also taken into account. HME resulted in amorphous E-EPO/IBU solid dispersions and solid dispersions containing a partially crystalline plasticizer in the case of E-EPO/IBU/COM extrudates. Interactions between the components of the extrudate were also studied using infrared spectroscopy (FTIR-ATR). The occurrence of such interactions in the studied system, which improve the stability of the obtained solid polymer dispersions, was confirmed. On the basis of DSC thermograms and XRPD diffractograms, it was found that amorphous solid dispersions were obtained. In addition, their stability was confirmed in accelerated conditions (40 °C, 75% RH) for 28 days and 3 months. The release profiles of prepared tablets showed the release of 40% to 63% of IBU from the tablets within 180 min in artificial gastric juice solution, with the best results obtained for tablets with E-EPO/IBU extrudate prepared at a processing temperature of 140 °C.

Chlorinated paraffins in multimedia during residential interior finishing: Occurrences, behavior, and health risk

Though with bioaccumulation and toxicity, chlorinated paraffins (CPs) are still high produced and widely utilized in various daily necessities for extender plasticization and flame retardation. CPs can be released during the reprocessing processes of finishing materials and distributed in multi-environmental media. Herein, concentrations and compositions of CPs in four representative media including interior finishing materials, PM10, total suspended particulate (TSP), and dust samples collected from eight interior finishing stages were studied. Unexpectedly, CP concentrations in ceramic tiles was found to be high with a mean value of 7.02 × 103 μg g−1, which could be attributed to the presence of CPs in the protective wax coated on ceramic tiles surfaces. Furthermore, the pollution characteristics of short-chain and medium-chain CPs (SCCPs and MCCPs) in those samples were inconsistent. According to the investigation regarding Kdust−TSP and KPM10-TSP, the occurrence and distribution of CPs in indoor atmospheric particles (PM10 and TSP) and dust were highly affected by reprocessing processes (cutting, hot melting, etc.) compared to that in the finishing materials. Moreover, dermal contact was the primary pathway of CP exposure for the occupational population (interior construction workers) for most interior finishing stages, and the interior finishing process is the prime CP exposure period for the occupational groups. As suggested by our assessment, though hardly posing an immediate health risk, CPs exposure still presents unneglected adverse health effects, which calls for adequate personal protections during interior finishing, especially in developing countries.

In-situ aligning magnetic nanoparticles in thermoplastic adhesives for contactless rapid joining of composite structures

Magnetic nanoparticles of high magnetic susceptibility, such as magnetite (Fe3O4), have been used for wireless heating of adhesives and composites through the magnetic hysteresis loss mechanism, but the high concentrations of nanoparticles needed to meet heating performance targets can degrade mechanical properties. Herein, we present an in-situ aligning method to enhance the heating efficiency of magnetite nanoparticles in a nylon thermoplastic matrix without adversely affecting its mechanical strength. A composite adhesive was made by dispersing Fe3O4 nanoparticles in a nylon matrix followed by hot melting. Experimental results show that by subjecting the adhesive to an alternating magnetic field during the hot-melt process, its heating rate can be improved by 200% compared to that without applying the magnetic field. The improvement in the heating performance has been identified to stem from the alignment of the ease axis of the magnetic nanoparticles. This in-situ aligning technique enables better induction heating performance with the same amount of Fe3O4 nanoparticles, avoiding the agglomeration problem of high nanoparticle concentrations. Moreover, this technique makes it possible to develop high-performance self-heating thermoplastic adhesive for reversible bonding and self-healing solution with a wide range of applications, such as bonding and debonding of composites, temporary attachment of systems, and recyclable bonded structures.

An impact-strengthening, reusable hot-melt structural adhesive derived from branching polyurethane-based supramolecular topology capped by self-complementary hydrogen bonding UPy motifs

The miniaturization and reliability of portable electronics are increasingly dependent on structural adhesive while developing detachable, reusable, and recyclable adhesives remain great challenge. Herein, we developed a novel strategy of incorporating self-complementary quadruple hydrogen bonds into multi-branch polyurethane as terminal motifs to construct supramolecular adhesive. Impressively, the as-synthesized TPU-UPy was endowed with a high adhesion strength of 6.8 MPa for steel and featured excellent multiple reusability with more than 70% of the original adhesion strength remained even after reuse for five times. More importantly, it exhibited increasing trend of adhesive strength as the stretching speed increases, suitable for application of anti-impact. The way of generating UPy motifs by this synthetic route did not involve excessive consumption of reactants, which was potential to be industrialized. Thus, the TPU-UPy is a candidate hot melt adhesive that can be put into practical use of portable electronics encountering occasional impact.