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In this work, a technique for constructing a three‐dimensional (3D) skeleton of hexagonal boron nitride (h‐BN) using sugar as the fulcrum and preparing composites by embedding in the epoxy (EP) in a vacuum environment is proposed. The study of thermal conductivity (TC) in polymer composites is conducted through a blend of techniques: laser flashing, theoretical modeling, and finite element simulation. The h‐BN skeleton exhibits a honeycomb structure through the scanning electron microscopy findings. Further investigation using finite element simulation demonstrates that conductive networks are formed by the h‐BN skeleton within the composites, leading to a notable enhancement in TC. Specifically, the composite for h‐BN/EP reaches a TC of 2.25 W/m K when composed of 52 vol% h‐BN. A dielectric loss of 0.008 for the composite with the same h‐BN loading shows a considerable improvement. The compressive yield strength of the 3D h‐BN/EP composites reached 312 MPa at 5 vol% h‐BN loading. [ABSTRACT FROM AUTHOR]

The disposal of plastic foam, mostly composed of polystyrene, poses significant environmental challenges due to its high popularity, slow degradation, and low cost. To address this problem, recycling polystyrene foam waste (PF) has emerged as a promising solution to reduce plastic pollution. This paper presents a novel approach to mass‐produce highly ordered, porous honeycomb‐patterned film (hc‐film) using wasted PF as the raw material. The hc‐film is produced using an improved phase separation (IPS) method that utilizes methanol as a suitable pore inducer and template droplet stabilizer. Methanol provides the hc‐film with customizable features such as pore ordering, size, and separation. The freestanding hc‐film, achieved by adopting a water‐soluble polystyrene sulfonate as a scarified layer, can be transferred and utilized as a flexible mold to pattern various solid substrates with complicated surface morphologies using the pre‐impregnated technique. This study demonstrates the potential of this cost‐effective and efficient approach for various applications, such as super/anti‐wetting surfaces, microelectronics, optical devices, sensors, and nanogenerators. [ABSTRACT FROM AUTHOR]

Accelerating the curing of epoxy/aromatic amine adhesives and improving their toughness are challenges in heat‐resistant epoxy structural adhesives. Herein, we report an epoxy/aromatic amine adhesive accelerated curing system with an oxo‐centered trinuclear (chromium III) complex, which is toughened using a thermoplastic block copolymer (TPBC). The reaction characteristics, heat resistance, microstructure, and bonding properties of the accelerated epoxy adhesives were analyzed. The reaction peak temperature of the epoxy with 3% catalyst was 113.1°C, which was 113.6°C lower than that of epoxy without catalyst, and the modified epoxy resin demonstrated a potential for rapid curing at medium temperature. The glass transition temperature of the TPBC‐toughened epoxy adhesive was 125°C after curing, indicating excellent thermal stability after medium temperature curing. The introduction of the TPBC increased the single‐lap shear strength of the epoxy adhesive without reducing its heat resistance. The shear strength at room temperature and 120°C of the modified epoxy adhesive with 50 phr of TPBC was 25.2 and 10.9 MPa, respectively. Moreover, the epoxy film adhesive exhibited outstanding bonding properties when used in the bonding of lightweight honeycomb sandwich structures. [ABSTRACT FROM AUTHOR]

In order to realize high recovery stress and large recoverable compression strain, by drawing inspiration from the bow‐and‐bowstring principle, we designed the temperature switch and actuator separately to reduce the response temperature when the shape recovers, thereby improving the storage modulus of the actuator and recovery stress. Meanwhile, a self‐template method was used to synthesize shape memory polymer (SMP) which has an actuator with a honeycomb structure to further improve the recovery force. Compared with the loofah‐like interpenetrating network structure SMP (SMP‐L) obtained using the traditional method, the SMP with a honeycomb‐like actuator (SMP‐H) has three times higher recovery stress than SMP‐L. SMP‐H can lift loads more than 400 times its own weight and has three times higher recovery lifting stress than SMP‐L. SMP‐H also has self‐healing, reprocessing, and recyclable properties due to its special honeycomb‐like actuator. This new synthesis strategy could provide opportunities for the wider application of SMPs. [ABSTRACT FROM AUTHOR]

Designing aramid nanofiber (ANF) aerogel with excellent microstructure and high thermal insulation property is benefit for applications in integrated thermal management system. To obtain a structurally controllable ANF‐based aerogel, the cellulose nanofiber (CNF) and poly (vinyl alcohol) (PVA) were 'stiff–soft' synergistic to improve the microstructure. The cobweb like structures distributed in the honeycomb layered pores of the CNF/PVA/ANF composite aerogel which was conducive to the performance and application of composite aerogel. The resulting CNF1/PVA1/ANF composite aerogels are highly porous (99.12%) and tiny volume shrinkage (4.65%), leading to excellent thermal insulation performance (26.83 mW/m·K). The 'stiff–soft' feature endows the composite aerogels high flexibility as well as large compression strength. These favorable multi‐features make the CNF/PVA/ANF composite aerogels ideal advanced material for aerospace, industrial, and commercial applications. [ABSTRACT FROM AUTHOR]

With the continuous development of bionics, such as, geckos and virginia creeper with both superhydrophobic and super‐adhesive, the surface wetting and super‐adhesive properties of various porous materials have attracted extensive attention of the scientific and medical communities. Here, the honeycomb polyurethane (PU) porous films with strong adhesion were successfully prepared by microphase separation method and the effects of growth parameters on their microstructure and adhesive strength to ice were investigated. It was found that a high relative humidity (e.g., 100%) and a low solution concentration (e.g., 2%) facilitated the formation of ordered honeycomb PU porous films, and as‐prepared PU pores with average pore diameter as small as 5 μm are better ordered and more uniform than these in related documents. Although the contact angle of water droplets on the surface of PU porous films increased from the premodification value of 85–130° to more than 160° after surface modification with polydopamine (PDA), the corresponding rolling angle remained approximately constant (180°), indicating that the surface of PU porous films has strong adhesion similar to geckos and virginia creeper. Furthermore, at lower temperature, the PU porous films exhibited the high adhesive strength of 142.13 kPa on ice, which was strongly dependent on the porous microstructures and surface compositions. The improved adhesive behavior to ice of honeycomb PU porous films modified with PDA provides new strategies for surface modification of materials and potential applications in medical domain. [ABSTRACT FROM AUTHOR]

ABSTRACT Polycaprolactone is well known as a healing agent material in crack self-healing applications but not as a structural material. In this study, the focus is on the durability and energy absorption of honeycomb structure made from polycaprolactone through three-dimensional (3D) printing. The mechanical behavior of honeycomb structures was investigated through in-plane quasi-static compression tests at temperatures of 5 °C, room temperature (22 °C), and 40 °C. Energy absorption efficiency and energy absorption capability at different temperatures and in different loading directions was investigated according to the selected stepping upward stress. The 'shape recovery' ratio after compression deformation was calculated. The results reveal that the polymeric honeycomb structure has exceptional repeatability under compressive loads. Specimens with relative density 0.20 showed high energy absorption capability, up to 0.988 J cm−3. After the removal of compression loads, specimens recovered up to 80% after the first deformation and up to 70% after the fifth deformation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46018. [ABSTRACT FROM AUTHOR]

ABSTRACT Shape memory polymers (SMPs) attract widespread attention because they are able to maintain a temporary deformation after unloading and recover the initial shape under high temperature conditions. Based on a three-dimensionally constitutive equation of SMPs, a finite element program is followed by compiling user-defined material subroutine, which describes the shape memory behavior of thermo-mechanical experiment. A honeycomb core using SMP is designed, which has the ability to recover the initial shape after deformation and be used as a smart core for sandwich structures. To prove their advantages in the engineering application, a series of thermodynamic behaviors of the SMP honeycomb core are simulated, including loading at high temperature, cooling, unloading at the low temperature, and recovering original shape on heating. Shape memory behaviors of tensile, compressive, bending, and locally sunken deformations are demonstrated and the effect of time and temperature on the recovery process is discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45672. [ABSTRACT FROM AUTHOR]

ABSTRACT The honeycomb porous films of tadpole-shaped polyhedral oligomeric silsesquioxane fluorinated acrylates copolymers were fabricated through breath figure method. The static hydrophobic properties were studied through water contact angles (CAs) and the rim width/pore size ( W/ D) values. It was found that the low W/ D value and high fluorine content generally indicated a high water CA. The properties such as morphology variations, energy conversion, contact diameter, adhesive, and repulsive forces were investigated on the porous and pincushion films. Furthermore, the kinetic energy of the droplet was converted into surface energy and internal energy dissipation after it impacted the surface. The residual energy made the droplet to recoil and influenced the bouncing height. The contact diameter and bouncing height characterized the energy level of the surface, and determined the surface energies of the copolymer/water/air system as well as the wettability. Finally, the adhesion and repulsion of water droplet on different surface at the times of establish contact, maximum contact diameter, and maximum bouncing height were compared. This work was helpful for us to further understand and control the adhesive force and the repulsive force on the porous and pincushion structure films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45476. [ABSTRACT FROM AUTHOR]

ABSTRACT In this work, composite materials containing aramid honeycomb core (ARHC) reinforced isocyanate-based polyimide foams (IBPIFs) were prepared by a simple free-foaming process. The flame retardance, smoke performance, and mechanical property of the composite materials along the transverse (W) and longitude (L) directions of ARHC were studied. Results of limiting oxygen index and cone calorimeter reveal that the space partition action of ARHC on IBPIFs, barrier action of honeycomb structure on fire, and generation of straight, flurry and porous char layer in the honeycomb cells during combustion effectively enhanced the flame retardance of IBPIFs. Mechanical property test shows that IBPIFs and ARHC presented a positive synergetic effect, and ARHC increased the compression strength of IBPIFs along the W and L directions of ARHC by approximately 300%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45041. [ABSTRACT FROM AUTHOR]

ABSTRACT In this work, a polyaniline honeycomb nanocomposite is synthesized via chemical route and Breath Figure technique and characterized through Fourier Transform Infrared, X-ray diffraction, thermogravmetric analysis, and morphological analysis (SEM and TEM). The DC, AC conductivities, and Mott's VRH parameters have been measured in the temperature range from 303 to 373 K and frequency range from 20 Hz to 1 MHz. The DC conductivity of the nanocomposite enhanced and AC-conductivity is attributed to overlapping large polaron tunneling (OLPT) mechanism. The composite is tested for supercapacitor properties. A specific capacitance of 554 F/g and energy density of 76.9 Wh/kg at 1 A/g current density, and high power density of 2.00 kW/kg at 4 A/g indicates more feasibility of the redox process. Electrochemical impedance spectroscopy and cyclic voltammetry reveals that the nanocomposite is an excellent supercapacitor electrode material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44536. [ABSTRACT FROM AUTHOR]

ABSTRACT Highly ordered honeycomb-patterned polystyrene surfaces are efficiently prepared by static breath figure method. The structured arrays can be obtained by casting a dilute solution polymer on glass substrates under various conditions. Tetrahydrofuran and chloroform are used as solvent to form cavities of several micrometers. The analysis of the surfaces indicates nonlinear relation between concentration and pore size in this system. Voronoi tessellations of the polystyrene surfaces at different relative humidity (RH) are achieved, and each conformational entropy determined. Optimum parameters of concentration and RH are obtained for both solvents. Analysis of hole size distribution and conformational entropy demonstrates the high order of the films obtained. This is a promising method for the fabrication of homogeneous and highly porous films from polystyrene. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44004. [ABSTRACT FROM AUTHOR]

ABSTRACT Stochastic honeycomb sandwich panels are fabricated through a simple process of melt-stretching molten polymer blanks. This study mapped their internal architecture over a wide domain of material process space, defined by the areal density and melt-stretch rate. The internal architectures were characterized using both topological and geometric parameters: the node density, the total length of webs, the Euler number , and a characteristic fractal area fraction. The mechanical response of the polymer melt was quantified in terms of peak stress and stiffness, along with apparent elongation viscosity. The observed architectures and polymer melt responses were consistent with a varying activated entanglement density in the melt and illustrate how the fabrication conditions can be tuned to obtain a desired architecture. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42174. [ABSTRACT FROM AUTHOR]

ABSTRACT Honeycomb-structured porous films have been widely applied in various industrial areas such as chemical sensors, tissue engineering, and micro reactors. In this article, one novel self-assembly approach is proposed to fabricate well-ordered polyphenylene oxide honeycomb films by a facile control of spraying ultrasonic humidifier atomized water droplets. Proper spraying retention time is necessary for porous films formation with highly uniform pore size. The effect of atomized water droplets flux on the pore size and the regularity of the hexagonal arrays were experimentally investigated. The pore size became larger with increasing the solution concentration. Especially, honeycomb films with two-level pores were fabricated by spraying atomized water droplets two times and the influence of interval time on the two-level honeycomb films formation was investigated. Apart from analysis of structural characteristics, self-assembly mechanism was also discussed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41163. [ABSTRACT FROM AUTHOR]

Unidirectional freezing is a simple and environmentally friendly method for preparing polymeric porous materials from polymer solutions for use in various applications. In this study, a unique, multihollow-core honeycomb structure was prepared from diurethandimethacrylate (DUDM) in a 1,4-dioxane (Dx) and tertiary butanol (TBA) binary solvent system via unidirectional freezing, subsequent photopolymerization and freeze-drying. The multihollow-core honeycomb consists of two different hollow tubular structures: one structure is noncircular with an atypical cross-sectional area, and the other is circular and measures approximately 5-10 μm in diameter. Both structures are aligned parallel to the freezing direction. These hollow structures were formed by using the sequential growth of Dx and TBA crystals as a template. During the unidirectional freezing process, the Dx crystals grew in the solution along the freezing direction and expelled DUDM and TBA from its crystalline phase into the solution. When the freezing temperature was further decreased, small, needle-shaped TBA crystals grew along the freezing direction and were confined by the Dx crystals. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

A well-ordered micrometer-scale honeycomb monolith porous polymeric material with aligned channels was successfully prepared from UV-curable urethane diacrylate monomer and 1,4-dioxane solutions by conducting unidirectional freezing, photopolymerization, and sublimation of the frozen solvent. UV light was irradiated into the frozen solution, and the monomer was photopolymerized and solidified in a template of 1,4-dioxane crystals. The effects of monomer concentration, freezing rate, and viscosity of the solution on the porous structure were investigated. High monomer concentration increases the solution viscosity, decreases the diffusivity of solute, and consequently, increases the degree of the supercooling. Thus, the pore size was decreased, and the channel wall feature was changed from smooth to dendrite as the solution viscosity increased. Pre-UV irradiation was also conducted before the unidirectional freezing process so as to control the solution viscosity and change the porous structure. Experiments elucidated that the solution viscosity is one of the key factors of determining the cell structure in the unidirectional freezing technique. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The article reports on the synthesis of a soluble polyimide from 2,2'-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and 3,3'-dimethyl-4,4'-diaminodiphenylmethane (DMMDA) using a two-step method. According to the authors, the resulting polyamide had good solubility in strong bipolar solvents, as well as in common low-boiling point solvents. The BPADA-DMMDA polyamide was then dissolved in chloroform. They also reveal that honeycomb films were formed from the BPADA-DMMDA/CHCl3 solution.

Effects of bentonite concentration on morphology and permeation characteristics of bentonite‐doped polysulfone membranes were investigated. Solubility sphere for bentonite was constructed to estimate its solubility parameter. Thermodynamic modeling of phase inversion of this system was carried out using Flory–Huggins theory. The trade‐off between thermodynamic and kinetic parameters was used to predict the membrane morphology for bentonite concentration varying from 0 to 5 wt %. The porosity of bentonite‐doped membranes decreased up to 3 wt % that increased thereafter. Morphological analysis showed dense cross section with finger‐like macrovoids at 3 wt % beyond which it changed to honeycomb structure with large circular voids. Permeability of 3 wt % membrane was the lowest (5.6 × 10−12 m/Pa s) with 95% bovine serum albumin rejection. Contact angle of the membranes decreased from 83 to 66° with bentonite addition making the membrane more hydrophilic. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48450. [ABSTRACT FROM AUTHOR]

Epoxy film adhesives are of prime importance for the fabrication of lightweight honeycomb structures for aerospace industries. This work involves the synthesis of oxazolidinone modified epoxy novolac resin (EPN‐OXA) via the reaction of EPN and toluene diisocyanate. EPN‐OXA was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and epoxy equivalent weight. EPN‐OXA was blended with solid epoxy resin, polyethersulfone (PES) toughened liquid epoxy resin, dicyandiamide, and aluminum powder to fabricate a film adhesive curing at 170–180 °C. Effect of additives and curative on the adhesive property was studied to optimize the composition. Effect of PES on the optimized composition was studied in detail. The best composition exhibited lap shear strength of 370 ± 10 kgf cm−2 at 25 °C and the strength was retained to 75% at −196 °C and 52% at 120 °C. PES significantly enhanced the interfacial strength at different temperatures (~1.6‐fold at −196 and 25 °C and ~1.8‐fold at 120 °C). It also improved tensile strength and fracture toughness by 1.4‐ and 2‐fold, respectively. The toughening effect of PES was further confirmed by scanning electron microscopy images. PES marginally reduced the glass‐transition temperature and it exhibited no effect on thermal stability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47520. [ABSTRACT FROM AUTHOR]

"Inverse emulsion"‐"breath figures" (Ie‐BF) method was introduced for fabricating porous films with protein arrays decorating the interior of the obtained polymeric pores. Compared with the traditional BF method in which only hydrophobic or amphiphilic components could be used, Ie‐BF method created a system with water phase carrying water‐soluble protein before solution casting, which makes it possible to obtain patterned protein arrays within the BF structure in one‐step. The stability of the inverse emulsion system is an intractable problem solved by high shearing emulsification. Experimental parameters, including the concentration of the matrix polymer, water/oil ratio of the IE, amount of both emulsifier and protein in IE, were evaluated for establishing an optimal condition to prepare fine BF arrays by following the Ie‐BF method. Proteins tagged with fluorescein isothiocyanate were added into the emulsion to cast films, and pores efficiently enriched by proteins were revealed by the images of fluorescence microscope, indicating the successful preparation of protein arrays. Among all the approaches of establishing patterned structures of biomacromolecules, Ie‐BF shows promising potential in future applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47084. [ABSTRACT FROM AUTHOR]