Nanoengineered Surfaces Research Articles

Self-removing salt crystals

A newly discovered mechanism by which salt crystals leap off nanoengineered surfaces may lead to the development of industrial materials that resist the buildup of minerals from fresh and salt water.

Manipulation of Serum Protein Adsorption by Nanoengineered Biomaterials Influences Subsequent Immune Responses.

The adsorption of serum proteins on biomaterial surfaces is a critical determinant for the outcome of medical procedures and therapies, which involve inserting materials and devices into the body. In this study, we aimed to understand how surface topography at the nanoscale influences the composition of the protein corona that forms on the (bio)material surface when placed in contact with serum proteins. To achieve that, we developed nanoengineered model surfaces with finely tuned topography of 16, 40, and 70 nm, overcoated with methyl oxazoline to ensure uniform outermost chemistry across all surfaces. Our findings revealed that within the studied height range, surface nanotopography had no major influence on the overall quantity of adsorbed proteins. However, significant alterations were observed in the composition of the adsorbed protein corona. For instance, clusterin adsorption decreased on all the nanotopography-modified surfaces. Conversely, there was a notable increase in the adsorption of ApoB and IgG gamma on the 70 nm nanotopography. In comparison, the adsorption of albumin was greater on surfaces that had a topography scale of 40 nm. Analysis of the gene enrichment data revealed a reduction in protein adsorption across all immune response-related biological pathways on nanotopography-modified surfaces. This reduction became more pronounced for larger surface nanoprotrusions. Macrophages were used as representative immune cells to assess the influence of the protein corona composition on inflammatory outcomes. Gene expression analysis demonstrated reduced inflammatory responses on the nanotopographically modified surface, a trend further corroborated by cytokine analysis. These findings underscore the potential of precisely engineered nanotopography-coated surfaces for augmenting biomaterial functionality.

Nanostructured Surfaces Enhance Nucleation Rate of Calcium Carbonate.

Nucleation and growth of calcium carbonate on surfaces is of broad importance in nature and technology, being essential to the calcification of organisms, while negatively impacting energy conversion through crystallization fouling, also called scale formation. Previous work studied how confinements, surface energies, and functionalizations affect nucleation and polymorph formation, with surface-water interactions and ion mobility playing important roles. However, the influence of surface nanostructures with nanocurvature-through pit and bump morphologies-on scale formation is unknown, limiting the development of scalephobic surfaces. Here, it is shown that nanoengineered surfaces enhance the nucleation rate by orders of magnitude, despite expected inhibition through effects like induced lattice strain through surface nanocurvature. Interfacial and holographic microscopy is used to quantify crystallite growth and find that nanoengineered interfaces experience slower individual growth rates while collectively the surface has 18% more deposited mass. Reconstructions through nanoscale cross-section imaging of surfaces coupled with classical nucleation theory-utilizing local nanocurvature effects-show the collective enhancement of nano-pits.

Nano-engineered hierarchical natural fibre composites with localised cellulose nanocrystals and tailored interphase for improved mechanical properties

Natural fibre composites have been utilised in many applications such as automotive and buildings, thanks to their high specific properties and environmentally friendly nature. However, the incompatibility between hydrophilic natural fibres and hydrophobic polymer resins remains a longstanding issue in natural fibre composites. Inspired by nature's hierarchical structures and tailored functionalities, a nano-engineered hierarchical natural fibre composite has been developed in this study, utilising cellulose nanocrystals (CNCs) as localised nano-reinforcements at flax surfaces in a flax/bio-epoxy system. A simple and versatile spray coating technique was used to deposit CNCs on unmodified flax fibres, without using any chemical solvents. With the increased surface roughness and hence improved epoxy wetting on nano-engineered flax surfaces (3 wt% CNC loading), mechanical properties of the hierarchical composites have been significantly improved, with a 60 % increase in interlaminar shear strength, indicating an enhanced interfacial load transfer between flax and epoxy, alongside improved flexural modulus (14 %) and strength (23 %). This green approach without using any chemicals provides a scalable and sustainable way to develop tailored interfaces for natural fibre composites with enhanced resin wetting and mechanical properties.

Engineered Sustainable Omniphobic Coatings to Control Liquid Spreading on Food-Contact Materials.

The adhesion of sticky liquid foods to a contacting surface can cause many technical challenges. The food manufacturing sector is confronted with many critical issues that can be overcome with long-lasting and highly nonwettable coatings. Nanoengineered biomimetic surfaces with distinct wettability and tunable interfaces have elicited increasing interest for their potential use in addressing a broad variety of scientific and technological applications, such as antifogging, anti-icing, antifouling, antiadhesion, and anticorrosion. Although a large number of nature-inspired surfaces have emerged, food-safe nonwetted surfaces are still in their infancy, and numerous structural design aspects remain unexplored. This Review summarizes the latest scientific research regarding the key principles, fabrication methods, and applications of three important categories of nonwettable surfaces: superhydrophobic, liquid-infused slippery, and re-entrant structured surfaces. The Review is particularly focused on new insights into the antiwetting mechanisms of these nanopatterned structures and discovering efficient platform methodologies to guide their rational design when in contact with food materials. A detailed description of the current opportunities, challenges, and future scale-up possibilities of these nanoengineered surfaces in the food industry is also provided.

3D-printed versatile biliary stents with nanoengineered surface for anti-hyperplasia and antibiofilm formation

Biliary strictures are characterized by the narrowing of the bile duct lumen, usually caused by surgical biliary injury, cancer, inflammation, and scarring from gallstones. Endoscopic stent placement is a well-established method for the management of biliary strictures. However, maintaining optimal mechanical properties of stents and designing surfaces that can prevent stent-induced tissue hyperplasia and biofilm formation are challenges in the fabrication of biodegradable biliary stents (BBSs) for customized treatment. This study proposes a novel approach to fabricating functionalized polymer BBSs with nanoengineered surfaces using 3D printing. The 3D printed stents, fabricated from bioactive silica poly(ε-carprolactone) (PCL) via a sol–gel method, exhibited tunable mechanical properties suitable for supporting the bile duct while ensuring biocompatibility. Furthermore, a nanoengineered surface layer was successfully created on a sirolimus (SRL)-coated functionalized PCL (fPCL) stent using Zn ion sputtering-based plasma immersion ion implantation (S-PIII) treatment to enhance the performance of the stent. The nanoengineered surface of the SRL-coated fPCL stent effectively reduced bacterial responses and remarkably inhibited fibroblast proliferation and initial burst release of SRL in vitro systems. The physicochemical properties and biological behaviors, including in vitro biocompatibility and in vivo therapeutic efficacy in the rabbit bile duct, of the Zn-SRL@fPCL stent demonstrated its potential as a versatile platform for clinical applications in bile duct tissue engineering.

Acoustic sensing for investigating critical heat flux enhancement during pool boiling on electrodeposited copper foams

Nano-engineered surfaces have shown great promise in improving boiling heat flux and heat transfer coefficient for thermal management. Electrodeposited copper foams have attracted lots of scientific and engineering interest owing to their multi-tier structures. In this study, hierarchical copper foams with ultra-wicking properties were fabricated using cathodic deposition at different pH, including both acidic (pH 0) and basic (pH 10 and 12) solutions. Pendant droplet wicking tests and pool boiling experiments were performed to characterize the wicking flux and the critical heat flux (CHF) of the fabricated copper foams, respectively. The CHF enhancement mechanism in hierarchical copper foams was investigated with high-speed optical imaging and acoustic emission (AE) sensing during both the wicking and boiling tests. The results show that the wicking flux of the electrodeposited copper foams increases with the pH due to smaller dendrites and crystallites. Boiling CHF is also higher on the base-deposited copper foams (pH 10 and pH 12) than on the acid-deposited foams (pH 0). Consistent acoustic signatures are observed between wicking and boiling, i.e., smaller AE amplitudes are observed at higher wicking flux and higher CHF, which supports wicking-based CHF enhancement theories. A spike in the AE amplitude is observed at CHF during water boiling on copper foam surfaces due to the rapid growth of the vapor layer blanketing the boiling surface. During the nucleate boiling regime, the AE amplitude decreases with the heat flux in the low heat flux stage but increases with the heat flux in the high heat flux stage. This relationship is found to be due to the interplay of bubble size and bubble count in the stress field that bubbles exert on the heater surface. By analyzing the maximum bubble size, bubble count, and the power and dominant frequency of vapor fraction at varying heat fluxes from high-speed videos, our work shows no obvious effect of the surface structures on the dynamics of the apparent liquid–vapor interface. Combining the optical and acoustic analysis, it is concluded that the key role that surface structures play in CHF enhancement is improving capillary wicking underneath the bubbles rather than affecting the dynamics of the apparent liquid–vapor interfaces. This study not only explores the relationship between electrochemical control and wicking properties but also demonstrates the role of wicking in structure-enhanced boiling CHF through acoustic emission analysis.

Investigation of critical heat flux enhancement on nanoengineered surfaces in pressurized subcooled flow boiling using infrared thermometry

Enhancing the flow boiling critical heat flux (CHF) is beneficial to the economics and safety margins of many industrial applications cooled by boiling heat transfer. While many studies have shown that surfaces with hydrophilic nanoscale and micro-scale features can enhance CHF in pool boiling, it is still not clear how these engineered surfaces affect the CHF in subcooled flow boiling at ambient pressure, let alone high-pressure conditions. Here, two nano-engineered surfaces, i.e., a surface coated with a porous layer of hydrophilic silica nanoparticles and a surface coated with zinc oxide nanowires, were tested. Flow boiling tests with a 10 K subcooling and a mass flux of 1000 kg/(m2·s) were conducted at 1 bar and 4 bars using infrared thermometry diagnostics. At 1 bar, the CHF enhancement is around 15% for both coatings. At 4 bars, the CHF enhancement is around 17% for the nanowire surface, and around 25% for the nano-porous surface. Infrared thermometry measurements reveal that the CHF enhancement comes from an increase of both two-phase heat transfer and single-phase heat transfer mechanisms, which is due to a change of bubble dynamics on the nanoengineered surfaces. It is also shown that the boiling crisis can be predicted using a percolation model based on Monte Carlo (MC) simulations.

Experimental Characterization of Photoemission from Plasmonic Nanogroove Arrays

Metal photocathodes are an important source of high-brightness electron beams, ubiquitous in the operation of both large-scale accelerators and table-top microscopes. When the surface of a metal is nanoengineered with patterns on the order of the optical wavelength, it can lead to the excitation and confinement of surface-plasmon-polariton waves that drive nonlinear photoemission. In this work, we aim to evaluate gold plasmonic nanogrooves as a concept for producing bright electron beams for accelerators via nonlinear photoemission. We do this by first comparing their optical properties to numerical calculations from first principles to confirm our ability to fabricate these nanoscale structures. Their nonlinear photoemission yield is found by measuring emitted photocurrent as the intensity of their driving laser is varied. Finally, the mean transverse energy of this electron source is found using the solenoid-scan technique. Our data demonstrate the ability of these cathodes to provide a tenfold enhancement in the efficiency of photoemission over flat metals driven with a linear process. We find that these cathodes are robust and capable of reaching sustained average currents over 100 nA at optical intensities larger than $2\phantom{\rule{0.2em}{0ex}}\mathrm{GW}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}2}$ with no degradation of performance. The emittance of the generated beam is found to be highly asymmetric, a fact we can explain with calculations involving the also asymmetric roughness of the patterned surface. These results demonstrate the use of nanoengineered surfaces as enhanced photocathodes, providing a robust air-stable source of high-average-current electron beams hopefully with great potential for industrial and scientific applications.

Response of Human Gingival Fibroblasts and Porphyromonas gingivalis to UVC-Activated Titanium Surfaces

Ultraviolet (UV) photofunctionalization has been demonstrated to synergistically improve the osteoblast response and reduce biofilm formation on titanium (Ti) surfaces. However, it remains obscure how photofunctionalization affects soft tissue integration and microbial adhesion on the transmucosal part of a dental implant. This study aimed to investigate the effect of UVC (100-280 nm) pretreatment on the response of human gingival fibroblasts (HGFs) and Porphyromonas gingivalis (P. g.) to Ti-based implant surfaces. The smooth and anodized nano-engineered Ti-based surfaces were triggered by UVC irradiation, respectively. The results showed that both smooth and nano-surfaces acquired super hydrophilicity without structural alteration after UVC photofunctionalization. UVC-activated smooth surfaces enhanced the adhesion and proliferation of HGFs compared to the untreated smooth ones. Regarding the anodized nano-engineered surfaces, UVC pretreatment weakened the fibroblast attachment but had no adverse effects on proliferation and the related gene expression. Additionally, both Ti-based surfaces could effectively inhibit P. g. adhesion after UVC irradiation. Therefore, the UVC photofunctionalization could be more potentially favorable to synergistically improve the fibroblast response and inhibit P. g. adhesion on the smooth Ti-based surfaces.

Recent progress in films with nanoengineered surfaces via bubble-induced self-assembly for energy applications

Films with nanoengineered surfaces can be generated by the bubble-induced self-assembly (BISA) for a variety of energy-related applications.

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review.

Liquid-vapor phase change phenomena such as boiling and condensation are processes widely implemented in industrial systems such as power plants, refrigeration and air conditioning systems, desalination plants, water processing installations and thermal management devices due to their enhanced heat transfer capability when compared to single-phase processes. The last decade has seen significant advances in the development and application of micro and nanostructured surfaces to enhance phase change heat transfer. Phase change heat transfer enhancement mechanisms on micro and nanostructures are significantly different from those on conventional surfaces. In this review, we provide a comprehensive summary of the effects of micro and nanostructure morphology and surface chemistry on phase change phenomena. Our review elucidates how various rational designs of micro and nanostructures can be utilized to increase heat flux and heat transfer coefficient in the case of both boiling and condensation at different environmental conditions by manipulating surface wetting and nucleation rate. We also discuss phase change heat transfer performance of liquids having higher surface tension such as water and lower surface tension liquids such as dielectric fluids, hydrocarbons and refrigerants. We discuss the effects of micro/nanostructures on boiling and condensation in both external quiescent and internal flow conditions. The review also outlines limitations of micro/nanostructures and discusses the rational development of structures to mitigate these limitations. We end the review by summarizing recent machine learning approaches for predicting heat transfer performance of micro and nanostructured surfaces in boiling and condensation applications.

DeltaPCA: A statistically robust method for analysing surface-enhanced Raman spectra for quantitative analyte detection

Surface-enhanced Raman spectroscopy using functionalised nanoparticles or nano-engineered surfaces provides a highly selective and sensitive technique for detecting and quantifying analyte binding. However, practical diagnostic and sensing applications are hindered by technical variability due to hot-spotting and analyte drift, as well as variability in sample preparation and substrate uniformity. In this work, we introduce a novel joint experimental design and computational analysis procedure to minimize and/or control for these sources of error. Sample variability is minimized by preparing functionalised nanoparticles with and without analyte under the same conditions, and then recording and analysing difference spectra. To account for technical variability, multiple spectra are recorded from each sample. The key novelty of our analysis procedure is that all information about sample and technical variability is retained through to the final comparative analysis step, and we apply principal component analysis twice - once to extract “variance-minimized” spectra as principal loading vectors and again to distinguish between samples with and without the target analyte. Proof of principle experiments using thiolated aptamers to detect CoV-SARS-2 spike protein reveal that analyte binding show that analyte binding primarily shows up as a depletion of free covalent stretching bands, coupled to appearance of corresponding hydrogen-bonded stretching bands. This is quite different from previous work which largely focusses on changes in the “fingerprint” region where we find that the signal may be obscured by greater technical variability. Our computational analysis code can be freely downloaded from https://github.com/dlc62/DeltaPCA.

Opportunities in Nano-Engineered Surface Designs for Enhanced Condensation Heat and Mass Transfer

AbstractRecent advancements in surface nano-engineering have spurred intense interests in their implementation for enhancing condensation heat transfer. When appropriately designed, nano-engineered surfaces not only lead to highly efficient transport mechanisms not achievable with conventional dropwise condensation (DWC), they also demonstrate the possibility of augmenting condensation of low surface tension fluids widely used in industry. These advantages are further enhanced by the development of highly scalable nanofabrication methods, which enable the potential transition from laboratory-scale prototypes to real-world industrial applications. In this review, we discuss the progress, opportunities, and challenges of enhancing condensation heat and mass transfer with nano-engineered surfaces. This article provides an overview of the recent developments in micro/nanoscale coating and structure fabrication techniques and performs a thorough comparison of their condensation performance, elucidating the complex interfacial transport mechanism involved. Surface structuring methods that are durable, scalable, and low-cost are essential attributes for large-scale industrial implementation. Here, the methods used to improve surface durability and demonstrations of nanostructure-enhanced meter-scale condensers are presented. Limitations are discussed and the potential techniques to overcome these challenges are summarized. Given the recent development of metal additive manufacturing (AM) technology and its growing relevance in manufacturing processes, we end this review by providing our perspectives on the opportunities in enabling surface nanostructuring of metal additive manufactured materials and the potential of nanometric–millimetric codesign optimization for the development of next-generation additively manufactured condensers.

Nanostructured antibacterial surfaces – What can be achieved?

Nanomaterials have emerged as the new weapon in the arsenal to fight antimicrobial resistance (AMR). While antibiotics have played a major role in combating infectious diseases, AMR presents a new challenge for sustainability in global health, food security and development. Inspired by nature, recent trending research has demonstrated that specific nanoscale surface patterns can rupture and kill bacteria on contact. Nano-engineered surfaces have demonstrated good capacity to prevent bacterial attachment and biofilm formation (the precursor to infection) and could be used as a strategic disinfectant for medically and industrially relevant materials. This opinion paper provides an overview of the role of nanotechnologies, specifically nanostructured surfaces, in aiding the development of infection-resistant surfaces.

Life Span of Slippery Lubricant Infused Surfaces.

Since their discovery a decade ago, slippery liquid infused porous surfaces (SLIPSs) or lubricant infused surfaces (LISs) have been demonstrated time and again to have immense potential for a plethora of applications. Of these, one of the most promising is enhancing the energy efficiency of both thermoelectric and organic Rankine cycle power generation via enhanced vapor condensation. However, utilization of SLIPSs in the energy sector remains limited due to the poor understanding of their life span. Here, we use controlled conditions to conduct multimonth steam and ethanol condensation tests on ultrascalable nanostructured copper oxide structured surfaces impregnated with mineral and fluorinated lubricants having differing viscosities (9.7 mPa·s < μ < 5216 mPa·s) and chemical structures. Our study demonstrates that SLIPSs lose their hydrophobicity during steam condensation after 1 month due to condensate cloaking. However, these same SLIPSs maintain nonwetting after 5 months of ethanol condensation due to the absence of cloaking. Surfaces impregnated with higher viscosity oil (5216 mPa·s) increase the life span to more than 8 months of continuous ethanol condensation. Vapor shear tests revealed that SLIPSs do not undergo oil depletion during exposure to 10 m/s gas flows, critical to condenser implementation where single-phase superheated vapor impingement is prevalent. Furthermore, higher viscosity SLIPSs are shown to maintain good stability after exposure to 200 °C air. A subset of the durable SLIPSs did not show change in slipperiness after submerging in stagnant water and ethanol for up to 2 weeks, critical to condenser implementation where single-phase condensate immersion is prevalent. Our work not only demonstrates design methods and longevity statistics for slippery nanoengineered surfaces undergoing long-term dropwise condensation of steam and ethanol but also develops the fundamental design guidelines for creating durable slippery liquid infused surfaces.

Dropwise Condensation by Nanoengineered Surfaces: Design, Mechanism, and Enhancing Strategies

AbstractCondensation is a common heat transfer process widely used in power plants, seawater desalination, and refrigeration industry. Highly efficient condensation is of great importance to save energy, improve operating efficiency of energy systems, and protect the environment. Compared with its filmwise counterpart, dropwise condensation has much higher heat transfer efficiency and is projected as the future condensation process. Various nanoengineered surfaces, including superhydrophobic surfaces, hybrid surfaces with different combinations of surface wettability, and slippery liquid‐infused surfaces, have been designed and applied to sustain and enhance dropwise condensation. In this review, the theories related to surface wetting and liquid mobility are summarized first, followed by an overview of the recent progress on these three major types of nanoengineered surfaces in dropwise condensation. Their contribution to heat transfer enhancement is also discussed, emphasizing on the promotion of nucleation and droplet departure. Given the critical impact of flooding in condensation heat transfer, studies that addressed flooding phenomenon at high subcooling are further reviewed. Various applications that use dropwise condensation surfaces are also summarized. Current challenges in dropwise condensation with nanoengineered surfaces are provided in the end, together with perspectives to accelerate its commercialization.

Influence of sterilization on the performance of anodized nanoporous titanium implants

Towards clinical translation of bioactive nano-engineered titanium implants, achieving appropriate sterilization and understanding its influence on the modified implant characteristics is essential. With limited studies exploring the influence of sterilization techniques on electrochemically anodized titanium with TiO2 nanostructures, we aimed to advance this domain by performing an in-depth evaluation of the influence of common sterilization techniques (ethanol immersion, various UV irradiation times, gamma irradiation, and dry/wet autoclaving) on TiO2 nanopores fabricated on micro-rough Ti surfaces (dual micro-nano) via single step anodization. Various sterilized surfaces were systematically compared in terms of topographical, chemical, crystalline, wettability and mechanical characteristics. Next, we investigated the protein adhesion capacity and functions of primary gingival fibroblasts (proliferation, adhesion/alignment and spreading morphology) to compare the bioactivity of the sterilized nanopores. Ethanol immersion, gamma irradiation and UV irradiation conserved the topography of the fabricated nanopores, while autoclave sterilization (both dry and wet) compromised the nanoporous structures. Various duration of UV-sterilization resulted in no significant changes in the surface topography and chemistry of the fabricated TNPs. Our findings revealed that UV irradiation is the most appropriate technique to sterilize nano-engineered titanium implants for appropriate wettability, protein adhesion capacity and enhanced metabolism and proliferation of human gingival fibroblasts (hGFs). This study systematically investigated the influence of sterilization on anodized nano-engineered titanium implants towards achieving reproducible outcomes (in terms of topography, chemistry and bioactivity), and found that UV irradiation holds great promise for application across different nano-engineered metal surfaces.

Untwining the topography-chemistry interdependence to optimize the bioactivity of nano-engineered titanium implants

Bioactivity is influenced by both the chemistry and the topography of the implant surface; however, the chemical and topographical modifications of nano-engineered implants often occur concurrently. Defining whether and how each of topography and chemistry tailor specific cellular activity has the potential to aid in the fabrication of the next generation of highly responsive implants. New approaches are needed to study implants with similar topography (but different chemistry) and similar chemistry (but different topography). To address this, we fabricated controlled nanotopographies on Ti implants using anodization resulting in similar topography and similar chemistry of Ti/TiO2 nanostructures. Next, we performed in-depth topographical and chemical analysis to evaluate the surface characteristics and quantified their protein adhesion properties. Further, human gingival fibroblasts (hGFs) were cultured on different surfaces to evaluate cell proliferation, metabolism, adhesion and spreading. Study found that protein adhesion and cell metabolism/proliferation are influenced by the topography (pore size and alignment) as well as the chemistry of the nanostructures. Additionally, cell alignment was significantly influenced by the topography of nanostructures. This study untwined the specific influence of dual topographically/chemically modified nano-engineered surfaces on bioactivity, aiming at optimized parameters towards the next generation of highly bioactive implants.

Molecular dynamics simulations of thin-film evaporation: The influence of interfacial thermal resistance on a graphene-coated heated silicon substrate

Two-phase liquid cooling on nanoengineered surfaces has shown great promise for tackling overheating in high performance microelectronics. At the nanoscale, phase change heat transfer can be affected substantially by the thermal resistance at the solid–liquid interface (also known as the Kapitza resistance). For example, surface modification by nanocoatings has been shown to efficiently enhance boiling heat transfer. However, there have been few studies on the effect of the Kapitza resistance on thin-film evaporative heat transfer. Here, the transport behavior of a liquid argon nanofilm evaporating on silicon (100) surfaces coated with different layers of graphene is analyzed using non-equilibrium molecular dynamics (MD) simulations. The results show that increasing layers of graphene coatings lead to a 136% increase in the Kapitza resistance and a 62% reduction in the evaporation rate. The large increase in Kapitza resistance is attributed to the strong repellence between graphene and argon molecules, manifested by a higher contact angle. These findings demonstrate the dominant role of interfacial thermal transport in the evaporation behavior of thin liquid films, and provide guidelines for selecting new materials when designing nanoengineered surfaces to realize improved evaporative cooling performance. • MD simulations of evaporation of liquid Ar on Si coated with graphene. • Influence of surface wettability on Kapitza resistance and evaporation. • Strong correlation between evaporative heat transfer and intermolecular interaction at solid–liquid interface.