Modulus Of Films Research Articles

Preparation of cellulose nanocrystals coated with polymer crystals and their application in composite films

AbstractIncreasing the dispersibility of cellulose nanocrystals (CNCs) as a reinforcing material is highly desirable to obtain composites with enhanced mechanical properties. To this aim, nanocomposite fibers (NCF(CNC/polymer)) were fabricated by coating CNCs with polymer crystals. Poly(vinyl alcohol) (PVA) and poly(vinyl alcohol‐co‐ethylene) (EVOH) were crystallized from a dilute solution in the presence of CNCs, which acted as nucleating agents for polymer crystal growth on the CNC surface. NCF consisting of CNCs coated with PVA crystals (NCF(CNC/PVA)) and CNCs coated with EVOH crystals (NCF(CNC/EVOH)) were successfully obtained. Both NCF(CNC/polymer) showed good dispersibility in water, even after drying, and were used to prepare composite films with improved mechanical properties. The reinforcement effect of NCF(CNC/PVA) was greater than that of pure CNCs and NCF(CNC/EVOH). The PVA composite films exhibited optical transmittance above 99% compared with additive‐free PVA films. No agglomerates appeared even under the optical microscopic observation of the PVA composite film, and NCF(CNC/PVA) dispersibility was extremely good. NCF(CNC/PVA)‐added PVA composite films exhibited increased glass transition temperature compared with additive‐free PVA films, and the crystallinity of the PVA film increased. The highly dispersed CNCs in the PVA matrix and the increase in the glass transition temperature and crystallinity caused an increase in the mechanical modulus of the PVA composite film at low NCF(CNC/PVA) content. Furthermore, the effect of the morphologies of cellulose nanofibers and CNCs on the mechanical properties of the composite films prepared using the respective NCFs was investigated.

Unusual High Hardness and Load-Dependent Mechanical Characteristics of Hydrogenated Carbon-Nitrogen Hybrid Films.

Mechanical components are exposed to a rigorous environment in a number of applications including engineering, aerospace, and automobiles. Thus, their service lifetime and reliability are always on the verge of risk. Protective coatings with high hardness are required to enhance their service lifetime and minimize the replacement cost and waste burden. Hydrogenated amorphous carbon including nitrogen-incorporated films, that are commonly deposited by plasma-enhanced chemical vapor deposition, are widely used for commercial protective coating applications. However, their mechanical hardness still falls into the moderate hard regime. This needs to be substantially enhanced for advanced applications. Here, we report the synthesis of very hard nanostructured hydrogenated carbon-nitrogen hybrid (n-C:H:N) films. The optimized n-C:H:N film displays a hardness of about 36 GPa, elastic modulus of 360 GPa, and reasonably good elastic recovery (ER) of 62.7%. The mechanical properties of n-C:H:N films are further tailored when nitrogen pressure is tuned during the growth. The realized remarkably improved mechanical properties are correlated with the films' structural properties and experimental growth conditions. We also conducted density functional theory calculations that show the trend for the elastic modulus of the amorphous carbon films with varying nitrogen concentrations matches well with experimentally measured values. Finally, we probed load-dependent mechanical properties of n-C:H:N films and found an anomalous behavior; some of the mechanical parameters, for instance, ER, reveal an irregular trend with indentation load, which we explain in the framework of the film-substrate composite concept. Overall, this work uncovers many unknown and exciting mechanical phenomena that could pave the way for new technological developments.

Fracture mechanics of microcrystalline/nanocrystalline composited multilayer chemical vapor deposition self-standing diamond films

Though microwave plasma chemical vapor deposition (MPCVD) diamond films exhibit extraordinary strength, the toughness improvement is still a huge challenge. The catastrophic fracture of the diamond films is undesirable in many applications, especially for the application of fabricating cutting tools. In the present study, adopting the pre-notched and unnotched cantilever bending tests, fracture behaviors of monolayer microcrystalline diamond (m-M), monolayer nanocrystalline diamond (m-N), and microcrystalline/nanocrystalline composited multilayer diamond films were observed and compared. Typical fracture mechanics, including Young's modulus (E), fracture strength (σF), and fracture toughness (KIC) of different diamond films were investigated. Effects of diamond crystal structure, intrinsic stress, and tensile-side roughness were systematically analyzed. Grain size and graphite phase content dominated the E of self-standing diamond films. Tensive-side surface roughness and intergranular bonding strength affected the σF. When the growth side in tension, E of the multilayer film (modulation period Λ = 3 h) was 16.0% lower than m-M and 26.6% higher than m-N, σF of multilayer film was 16.8% higher than m-M and 8.3% lower than m-N. At fixed Λ, doubling the total deposition period, E, σF, and KIC of the multilayer film increased 72.3%, 22.3%, and 2.7%, respectively. MCD/NCD composited multilayer architecture presented significant strengthening and toughening effects on self-standing diamond films.

Investigation of morphological surface features, wetting behavior and mechanical traits under various substrate temperatures for beta iron disilicide prepared via facing-targets sputtering

Using facing-targets sputtering, semiconducting iron disilicide (β-FeSi2) film layers were sputtered and coated on Si wafers owning (111) orientation. Under experimental conditions, the heating temperatures of the substrate (Tsubstrate) were varied at 525 °C, 550 °C, 600 °C and 660 °C. The acquired XRD patterns indicated a strong β(202/220) peak of around 29.1° for the β-FeSi2 films prepared at a Tsubstrate of at least 600 °C. The β-FeSi2 film surface prepared at a Tsubstrate of 525 °C comprised several crystallites, which were arranged to form a grain format at a higher Tsubstrate. The root mean square roughness for the film surface prepared at a Tsubstrate of 525 °C was 0.49 nm, where it increased to 0.98 nm, 2.39 nm, and 4.23 nm at Tsubstrate of 550 °C, 600 °C, and 660 °C, respectively. The films prepared at a Tsubstrate of 525 °C exhibited an average contact angle (θCA) of 91.15°, and improved to 103.80° after employing a Tsubstrate of 660 °C. These results hinted at the possibility of employing the β-FeSi2 films prepared at all Tsubstrate in the hydrophobic surface application. The estimated hardness and elastic modulus of the β-FeSi2 films prepared at Tsubstrate of 525 °C were 12.78 GPa and 190.98 GPa, respectively, which increased to 21.27 GPa and 248.67 GPa, respectively, for the films prepared at 660 °C. According to mechanical results, the β-FeSi2 films prepared at 660 °C exhibited the potential to be developed for use in hard coating application.

A hydrophobic coating on cellulose nanocrystals improves the mechanical properties of polyamide-6 nanocomposites

Recent demands for high-performance lightweight materials have brought researchers’ attention to various nanoparticles to reinforce polymeric materials. As such, sustainable and stiff cellulose nanocrystals (CNC) have become a popular candidate as nano-reinforcements. While CNC can offer great advantages, such as high mechanical properties and low density, it might agglomerate even in hydrophilic polymers because of its strong affinity to itself (intra and intermolecular hydrogen bonds) which prevents its broader use in industrial applications. This study aims to improve the compatibility between CNC and polyamide 6 (PA6) by a chemical modification that produces a surface polarity drastically different from non-modified CNC. The surface of CNC was rendered by the covalent coupling of stearic acid (SA) to the surface hydroxyl groups to produce stearate modified CNC (CNC SA). The effect of the modification was analyzed for CNC SA reinforced PA6 nanocomposites, and the results are compared to that of non-modified CNC reinforced PA6 samples. The addition of unmodified CNC to PA6 provided a modest improvement while the addition of CNC-SA provided substantial improvement on the modulus and tensile strength of the nanocomposite films.

Hemicellulose and Nano/Microfibrils Improving the Pliability and Hydrophobic Properties of Cellulose Film by Interstitial Filling and Forming Micro/Nanostructure.

In this paper, nano/microfibrils were applied to enhance the mechanical and hydrophobic properties of the sugarcane bagasse fiber films. The successful preparation of nano/microfibrils was confirmed by scanning electron microscope (SEM), X-ray diffraction (XRD), fiber length analyzer (FLA), and ion chromatography (IC). The transparency, morphology, mechanical and hydrophobic properties of the cellulose films were evaluated. The results show that the nanoparticle was formed by the hemicellulose diffusing on the surface of the cellulose and agglomerating in the film-forming process at 40 °C. The elastic modulus of the cellulose film was as high as 4140.60 MPa, and the water contact angle was increased to 113°. The micro/nanostructures were formed due to hemicellulose adsorption on nano/microfilament surfaces. The hydrophobicity of the films was improved. The directional crystallization of nano/microfibrous molecules was found. Cellulose films with a high elastic modulus and high elasticity were obtained. It provides theoretical support for the preparation of high-performance cellulose film.

Polymer nanofibers framework composite solid electrolyte with lithium dendrite suppression for long life all-solid-state lithium metal battery

The widespread deployment of lithium metal battery is limited by inhomogeneous electrodeposition of lithium metal (the growth of lithium dendrite), leading to pulverization, “dead” lithium and the unrestricted volume expansion of lithium metal anode. Owing to the high elastic modulus, thermal stability and electrochemical stability of polyimide, we design a novel composite solid polymer electrolyte blending with polyimide fibers framework paper. Polyimide fibers scaffold improves elastic modulus and tensile strength of composite electrolyte film. Effective ion transport network layers in electrolyte system are formed by adding polyimide fibers due to strong interaction between electron-withdrawing atoms and groups in the lithium salt for accelerating the dissociation of the lithium salt. Thus, polyimide composite electrolyte shows higher Li+ transfer number (∼2 times) than pure polyethylene oxide electrolyte, which is beneficial to regulate Li deposition for lithium dendrites inhibition. The electrochemical window of polyimide composite electrolyte is widened to 4.87 V after introducing stable physicochemical fibers framework, leading to high compatibility and stability with lithium metal anode. Therefore, the Li symmetrical battery with polyimide fibers framework composite electrolyte delivers low overpotential and long cycling life at different current densities. And the all-solid-state Li/LiFePO4 battery using this composite electrolyte reveals long cycling life (418 cycles), high Coulomb efficiency (99.97%), high capacity retention of 89.5% at 0.3 C, and good rate performance at 60 °C.

A Constrained Assembly Strategy for High-Strength Natural Nanoclay Film.

Developing high-performance materials from existing natural materials is highly desired because of their environmental friendliness and low cost; two-dimensional nanoclay exfoliated from layered silicate minerals is a good building block to construct multilayered macroscopic assemblies for achieving high mechanical and functional properties. Nevertheless, the efforts have been frustrated by insufficient inter-nanosheet stress transfer and nanosheet misalignment caused by capillary force during solution-based spontaneous assembly, degrading the mechanical strength of clay-based materials. Herein, a constrained assembly strategy that is implemented by in-plane stretching a robust water-containing nanoclay network with hydrogen and ionic bonding is developed to adjust the 2D topography of nanosheets within multilayered nanoclay film. In-plane stretching overcomes capillary force during water removal and thus restrains nanosheet conformation transition from nearly flat to wrinkled, leading to a highly aligned multilayered nanostructure with synergistic hydrogen and ionic bonding. It is proved that inter-nanosheet hydrogen and ionic bonding and nanosheet conformation extension generate profound mechanical reinforcement. The tensile strength and modulus of natural nanoclay film reach up to 429.0 MPa and 43.8 GPa and surpass the counterparts fabricated by normal spontaneous assembly. Additionally, improved heat insulation function and good nonflammability are shown for the natural nanoclay film and extend its potential for realistic uses.

The impact of SiO2 nanoparticles on the dilational viscoelastic properties of water-nonionic surfactant-fuel interface

Surfactants in ultra-low sulfur diesel (ULSD) can improve the stability of the emulsified water droplet by forming a thin film at the water-fuel interface. Emulsified water droplets block the oil spray nozzle and break down the engine, which need to be removed. For colliding emulsified water droplets, surfactant film with high viscoelastic modulus provides an obstacle to their coalescence. Micro/nanosized-SiO2 particles were added into ULSD to interrupt the arrangement of the surfactant film. After adding with 20 nm SiO2, the interfacial tension of water-monoolein-ULSD increased from 16.0 mN/m to 21.4 mN/m, and its viscoelastic modulus decreased from 17.1 mN/m to 10.9 mN/m, a decrease of 36.3%. It proved that the addition of nanosized SiO2 into water-monoolein-ULSD system increased the interfacial tension and reduced the viscoelastic modulus of the monoolein film. However, after adding nanosized SiO2, the viscoelastic modulus of the water-PETO-B-ULSD layer had no significant changes. Therefore, we concluded that 20 nm SiO2 disturbed the dense packing of monoolein as its adsorption to surfactants and the electrostatic repulsion force between them and the hydrophobic group, resulting in a decrease in elastic modulus. However, PETO-B had a complex branched structure leading to a loose packing, which had unoccupied adsorption sites and barely affected by the intrusion of 20 nm SiO2. Therefore, this research provided a strategy to add nanosized-SiO2 into W/O emulsions containing monoolein-like surfactant to reduce its stability.

Structural and dielectric properties of ion beam irradiated polymer/silver composite films

In this work, flexible nanocomposite films that are composed of silver (Ag) nanoparticles, polyaniline (PANI) and methylcellulose (MC) were manufactured using the casting solution fabrication technique. The manufactured films were characterized using X-ray diffraction and Fourier transform infrared spectroscopy, which confirming the preparation of the composite samples. The MC/PANI/silver films were then irradiated with oxygen (O)-ion beams at a range of fluences (8 × 1017, 16 × 1017 and 24 × 1017 ions/cm2). The electrical conductivity, complex impedance behavior, electric modulus and energy density of pure and irradiated films were determined throughout the frequency range 100 Hz–5 MHz. The oxygen-beam irradiation of MC/PANI/silver films caused a significant modification in dielectric parameters. Also, the dielectric constant ε′ improved from 0.68 to 3.17, and the conductivity was modified from 1.47 × 10−6 to 25.9 × 10−6 S/cm. The findings of the present study will pave the way for the use of irradiated MC/PANI/silver nanocomposite films in a variety of applications, including microelectronic devices, batteries and supercapacitors.

Debonding characterization of stiff film/compliant substrate systems based on the bilinear cohesive zone model

Interfacial debonding is one of the main failure modes of stiff film/compliant substrate systems, which are common in flexible electronics. In order to characterize their debonding process, we propose a theoretical model based on the bilinear cohesive zone model, where the stiff film acts like a membrane and the substrate is modeled by an elastic half-plane. The interfacial shear stress appears as a singular integral in the governing equations, and this term can be solved by expanding into the first-kind Chebyshev polynomials and further adopting the collocation method. The solutions of the present model are verified by the previous experimental data and the finite element analysis. The results indicate that the present model can not only capture the non-uniform deformation of the compliant substrate, but also describe the full debonding process including the elastic, elastic-softening and elastic-softening-debonding stages. Besides, the influences of film modulus, film thickness and interfacial properties on the debonding process are discussed. The present study can help us predict the debonding process of the stiff film/compliant substrate systems such as flexible electronics and guide the optimal design to prevent premature interfacial debonding.

Aluminium nitride thin films directly grown on conducting boron-doped nanocrystalline diamond films without using buffer layer for high frequency applications

Aluminium Nitride (AlN)-diamond hetero-structures are promising candidates for high frequency acoustic wave resonator applications. This paper reports the electrical, piezoelectric and mechanical properties of AlN films directly grown on boron-doped nanocrystalline diamond (B-NCD) films. X-ray diffraction (XRD) and Raman spectroscopy were used to determine the crystallinity of B-NCD and AlN films. The resistivity (∼8 ×107Ω.m) and dielectric constant (∼14) were obtained from the electrical characterisation of the fabricated Al/AlN/B-NCD capacitors. Piezoelectric coefficient (d33, 4.3 pmV−1) of AlN films was measured by piezo force microscopy (PFM) technique. Nanoindentation technique was used to determine the hardness (∼14 GPa) and elastic modulus (∼202 GPa) of AlN films. These different properties of AlN/B-NCD/Si (100) hetero-structure show that it will provide a high-performance platform to realize high frequency resonators for 5G applications.

Hybrid nanocomposite packaging films from cellulose nanocrystals, zinc sulfide quantum dots reinforced polylactic acid with fluorescent and antibacterial properties

AbstractIn this study, nanocomposite thin films from cellulose nanocrystals (CNCs), zinc sulfide (ZnS) quantum dots, and polylactic acid (PLA) with fluorescent and antibacterial properties were constructed via a simple, and fast route. ZnS nanoparticles were added to CNC following the hydrothermal process. The film casting method was used to form thin nanocomposite films. The transmission electron microscope analysis revealed the uniform dispersion and ZnS nanoparticles through CNC suspension and FTIR results confirmed the interaction between –OH group on CNC and ZnS nanoparticles. A noticeable emission peak at 475 nm for CNC‐ZnS signifies the suitability of CNC‐ZnS for the assembly of ZnS QDs. The addition of ZnS‐coated CNC into PLA film resulted in a bright blue fluorescence when exposed to ultraviolet light. The incorporation of 5 wt% CNCs loaded with ZnS quantum dots into PLA notably decreased bacterial growth in Escherichia coli and Salmonella, respectively. Data obtained from dynamic mechanical analysis underlined that the presence of 1 wt% ZnS‐coated CNC in PLA increased the storage modulus of nanocomposite films by 25%. The CNCs loaded with ZnS quantum dots showed effective fluorescent and antimicrobial properties to be used as food packaging material.

Dibutyl Itaconate and Lauryl Methacrylate Copolymers by Emulsion Polymerization for Development of Sustainable Pressure-Sensitive Adhesives.

Renewable polymers possess the potential to replace monomers from petrochemical sources. The design and development of polymeric materials from sustainable materials are a technological challenge. The main objectives of this study were to study the microstructure of copolymers based on itaconic acid (IA), di-n-butyl itaconate (DBI), and lauryl methacrylate (LMA); and to explore and to evaluate these copolymers as pressure-sensitive adhesives (PSA). The copolymer synthesis was carried out through batch emulsion radical polymerization, an environmentally friendly process. IA was used in a small fixed amount as a functional comonomer, and LMA was selected due to low glass transition temperature (Tg). The structure of synthesized copolymers was studied by FTIR, 1H-NMR, Soxhlet extraction, and molecular weight analyses by GPC. Furthermore, the viscoelastic and thermal properties of copolymer films were characterized by DMA, DSC, and TGA. The single Tg displayed by the poly(DBI-LMA-IA) terpolymers indicates that statistical random composition copolymers were obtained. Moreover, FTIR and NMR spectra confirm the chemical structure and composition. It was found that a cross-linked microstructure and higher molecular weight are observed with an increase of LMA in the feed led. The Tg and modulus (G′) of the copolymers film can be tuned with the ratio of DBI:LMA providing a platform for a wide range of applications as a biobased alternative to produce waterborne PSA.

Chirality-Dependent Mechanical Properties of Bundles and Thin Films Composed of Covalently Cross-Linked Carbon Nanotubes.

The effect of nanotube chirality on the mechanical properties of materials composed of single-walled carbon nanotubes (CNTs) is poorly understood since the interfacial load transfer in such materials is strongly dependent on the intertube interaction and structure of the nanotube network. Here, a combined atomistic-mesoscopic study is performed to reveal the effect of CNT diameter on the deformation mechanisms and mechanical properties of CNT bundles and low-density CNT films with covalent cross-links (CLs). First, the pullout of the central nanotube from bundles composed of seven (5,5), (10,10), (20,20), (17,0), and (26,0) CNTs is studied in molecular dynamics simulations based on the ReaxFF force field. The simulations show that the shear modulus and strength increase with decreasing CNT diameter. The results of atomistic simulations are used to parametrize a mesoscopic model of CLs and to perform mesoscopic simulations of in-plane tension and compression of thin films composed of thousands of cross-linked CNTs. The mechanical properties of CNT films are found to be strongly dependent on CNT diameter. The film modulus increases as the CNT diameter increases, while the tensile strength decreases. The in-plane compression is characterized by collective bending of whole films and order-of-magnitude smaller compressive strengths. The films composed of (5,5) CNTs exhibit the ability for large-strain compression without irreversible changes in the material structure. The stretching rigidity of individual nanotubes and volumetric CL density are identified as the key factors that dominate the effect of CNT chirality on the mechanical properties of CNT films. The film modulus is affected by both CL density and stretching rigidity of CNTs, while the tensile strength is dominated by CL density. The obtained results suggest that the on-demand optimization of the mechanical properties of CNT films can be performed by tuning the nanotube chirality distribution.

Fabrication and Characterization of High-Quality Epitaxial Nanocolumnar Niobium Films with Abrupt Interfaces on YSZ(001)

Niobium (Nb) is a promising refractory metal with a wide variety of technological applications in nanoelectronics, optoelectronics, photonics, and energy-related technologies. However, to further advance the field of nanoelectronics and nanophotonics, very high-quality Nb films with excellent structural order are needed. While much progress has been made in understanding the heteroepitaxy of Nb on oxide substrates, the underlying fundamental mechanisms, especially to realize films showing abrupt interfaces with the substrate and without needing the expensive equipment and/or processing under extreme conditions, remain a challenge. In this context, herein, we demonstrate an approach to stabilize the epitaxial, nanocolumnar bcc Nb films with highly ordered and abrupt interfaces on YSZ(001) substrates using simple and industrially widely adopted sputter deposition. 90 nm Nb films deposited onto YSZ(001) at 500 °C exhibit a strained, epitaxial structure. As evidenced in X-ray diffraction and transmission electron microscopy analyses, the structural quality of Nb films is driven by substrate-assisted selective nanocrystallization. Coupled with granular morphology and high structural quality, the optical properties measured by spectroscopic ellipsometry and reflectivity indicate highly reflective Nb films with enhanced optical constants. Corroborated with surface/interface quality, microstructure, and optical properties, the epitaxial Nb films exhibit excellent mechanical characteristics. The hardness and elastic modulus of the Nb epitaxial films were 18 and 240 GPa, respectively, which are attributed primarily to the growth of a compact nanocolumnar Nb epitaxial film on YSZ.

Estimation of the Young's Modulus of Nanometer-Thick Films Using Residual Stress-Driven Bilayer Cantilevers.

Precise prediction of mechanical behavior of thin films at the nanoscale requires techniques that consider size effects and fabrication-related issues. Here, we propose a test methodology to estimate the Young’s modulus of nanometer-thick films using micromachined bilayer cantilevers. The bilayer cantilevers which comprise a well-known reference layer and a tested film deflect due to the relief of the residual stresses generated during the fabrication process. The mechanical relationship between the measured residual stresses and the corresponding deflections was used to characterize the tested film. Residual stresses and deflections were related using analytical and finite element models that consider intrinsic stress gradients and the use of adherence layers. The proposed methodology was applied to low pressure chemical vapor deposited silicon nitride tested films with thicknesses ranging from 46 nm to 288 nm. The estimated Young’s modulus values varying between 213.9 GPa and 288.3 GPa were consistent with nanoindentation and alternative residual stress-driven techniques. In addition, the dependence of the results on the thickness and the intrinsic stress gradient of the materials was confirmed. The proposed methodology is simple and can be used to characterize diverse materials deposited under different fabrication conditions.

Optimizing mechanical properties in single-layered and multi-layered amorphous carbon coatings

Hydrogenated amorphous carbon coatings improve mechanical performance characteristics on a variety of substrates, resulting in widespread industry applications requiring a combination of high hardness, low coefficient of friction, wear resistance, elasticity, and adhesion. However, such a combination of properties is difficult to achieve. We investigated the structure, mechanical properties and scratch behavior in single-layered and multilayered amorphous carbon thin films made by plasma immersion ion implantation-based plasma enhanced chemical vapor deposition. The elastic modulus and hardness in single-layered films were improved up to 149 GPa and 17 GPa respectively by varying the applied bias voltage and pulse width. We observed a non-equivalent impact on mechanical properties and coating structure based on whether pulse width or frequency were varied in the duty cycle range of 1–12.5%. Mechanical properties were independent of pulse frequency within experimental uncertainty. All the single-layered films showed exceptional elastic recovery of ~70%. Film microstructures as measured by Raman microscopy showed that the maxima in modulus/hardness as a function of bias voltage correlated to films with the highest sp3 bonding fraction, highest sp2 disorder, and overall lowest disorder. The maxima in hardness and elastic modulus as a function of pulse width correlated with intermediate sp3 bonding fraction and highest overall disorder, but the sp2 disorder was nearly unchanged. Based on single-layer results, multilayers were developed. Nanoindentation and scratch testing showed that while multilayering preserved high hardness and improved friction behavior irrespective of the recipe, the scratch volume was strongly correlated to the hardness.

Tailoring the mechanical response of Ruddlesden Popper lead halide perovskites

Two dimensional (2D) Ruddlesden Popper perovskites have been extensively studied for their exceptional optical and electronic characteristics while only a few studies have shed light on their mechanical properties. The existing literature mainly discusses the mechanical strength of single crystal perovskites, however a study of structure tunability of 2D perovskite thin films is still missing. In this study, we report the effect of number of inorganic layers ‘n’ on elastic modulus of 2D, quasi-2D perovskites and 3D perovskite thin films using nanoindentation technique. Our studies indicate the role of orientation of the inorganic layers in perovskite films in tailoring their mechanical response. The experimental results have been substantiated using first principle density functional theory (DFT) calculations. We also report other important mechanical parameters namely, shear modulus, bulk modulus, Poisson’s ratio, Pugh’s ratio, Vickers hardness, yield strength and the universal elastic anisotropic index using DFT simulations. Anisotropy is observed in the elastic modulus of the materials under study and has been discussed in detail in the manuscript. Understanding the mechanical behavior of 2D Ruddlesden Popper perovskites thin film in comparison with conventional 3D perovskite offers intriguing insights into the atomic layer dependent properties and paves the path for next generation mechanically durable and novel devices.

Effect of adding carboxymethyl cellulose, zeolite and microcrystalline cellulose on the optical and mechanical properties of latex composite films

In this research, four-types of latex composite films which are carboxymethyl cellulose latex composite film, zeolite latex composite film, microcrystalline cellulose latex composite film and microcrystalline cellulose sodium hydroxide latex composite film were prepared by casting method. Drying time of all films formation is 24 hr. The average thickness of the dry film is 0.10 mm. The transparency of films were measured by UV-Vis spectrophotometer. It was found that the carboxymethyl cellulose latex composite film have more transparency than zeolite latex composite film, microcrystalline cellulose latex composite film and microcrystalline cellulose sodium hydroxide latex composite film respectively. The analysis of functional group of films were measured by ATR-FTIR technique. It was found that all types of films consist of O-H stretching group and C=O group without ether group of cellulose and Si-O-Al group of zeolite. The mechanical property of films were measured by Universal Testing Machine. It was found that the Young’s modulus of microcrystalline cellulose sodium hydroxide latex composite film was higher than microcrystalline cellulose latex composite film, zeolite latex composite film and carboxymethyl cellulose latex composite film respectively. The characteristic of stress-strain curve of films showed that all films were hard and brittle except microcrystalline cellulose latex composite films were hard and tough.