Loss Of Hydrophobicity Research Articles

Fragmentation and release of pristine and functionalized carbon nanotubes from epoxy-nanocomposites during accelerated weathering.

There is an increasing volume of nano-enabled materials in the market. Once composites containing nano-additives are disposed of, weathering could deteriorate their structures, releasing nanoparticles and risking exposure of humans and aquatic organisms. Composite degradation due to environmental aging continues, including structural deterioration resulting in cracking, fragmentation, and release of microplastics and nano-additives to the environment. This research aims to study the degradation and release of initially embedded nanomaterials (NMs) from composites and their toxicity. The molecular interaction of carbon nanotube (CNT)/polymer composites is critical for modifying the polymer properties. This study investigated the interactions of functional multiwalled carbon nanotube (MWCNT) composites which affect their release during accelerated weathering processes. Different epoxy-MWCNT composites were prepared by filling a polymer with pure MWCNTs and MWCNTs functionalized with acid () and amine () groups. The physical and chemical changes of aged composites were characterized by gravimetric analysis, contact angle measurements, FTIR, SEM, and laser confocal microscopy. A loss of hydrophobicity was observed for composite surfaces long before surface cracks materialized. Released polymer fragments and nanoparticles were analyzed in wash water using TEM, FTIR and Raman spectroscopy. The environmental risks for long-term use of CNT-polymer composites and the influence of fillers on the extent of chemical photodegradation depended on the combination of polymer and fillers. If nanoparticles are released from the matrix, the high surface-to-volume ratio and reactivity of NMs make them highly dynamic in environmental systems. Exposure to these released NMs could negatively affect human health and the environment. This study provides fragmentation and CNT particle release data that could describe how molecular-level interactions between functionalized CNTs and epoxy polymers affect the aging and release of CNTs. A toxicity assessment based on a reactive oxygen species (ROS) formation assay and MTS assay for cell viability and activity of the released polymer and CNT fragments and leachate showed moderate levels of cytotoxicity of released materials as compared to pristine epoxy plates.

Fluoropolymer Membranes for Membrane Distillation and Membrane Crystallization.

Fluoropolymer membranes are applied in membrane operations such as membrane distillation and membrane crystallization where hydrophobic porous membranes act as a physical barrier separating two phases. Due to their hydrophobic nature, only gaseous molecules are allowed to pass through the membrane and are collected on the permeate side, while the aqueous solution cannot penetrate. However, these two processes suffer problems such as membrane wetting, fouling or scaling. Membrane wetting is a common and undesired phenomenon, which is caused by the loss of hydrophobicity of the porous membrane employed. This greatly affects the mass transfer efficiency and separation efficiency. Simultaneously, membrane fouling occurs, along with membrane wetting and scaling, which greatly reduces the lifespan of the membranes. Therefore, strategies to improve the hydrophobicity of membranes have been widely investigated by researchers. In this direction, hydrophobic fluoropolymer membrane materials are employed more and more for membrane distillation and membrane crystallization thanks to their high chemical and thermal resistance. This paper summarizes different preparation methods of these fluoropolymer membrane, such as non-solvent-induced phase separation (NIPS), thermally-induced phase separation (TIPS), vapor-induced phase separation (VIPS), etc. Hydrophobic modification methods, including surface coating, surface grafting and blending, etc., are also introduced. Moreover, the research advances on the application of less toxic solvents for preparing these membranes are herein reviewed. This review aims to provide guidance to researchers for their future membrane development in membrane distillation and membrane crystallization, using fluoropolymer materials.

Influence of AC corona discharge on the hydrophobicity of silicone rubber surface in high-speed airflow environment

Corona discharge is one of the key factors that lead to the hydrophobicity loss of silicone rubber insulators used on the roof of high-speed trains. Based on the artificial experimental wind-tunnel platform, influences of AC corona intensity and airflow velocity on the hydrophobicity distribution of the silicone rubber surface were studied. According to the corona discharge phenomena and measured discharge current, influences of airflow velocity and voltage on the characteristics of corona discharge in a high-speed airflow environment were discussed. Results reveal that the hydrophobicity distribution on the silicone rubber surface shifts along the airflow direction in the high-speed airflow environment when the voltage is relatively high. When ionization zone develops to the needle-plate gap, the discharge path is deflected to the direction of airflow, which is responsible for the change of the hydrophobicity distribution. It is notable that the deflection distance decreases with the increase of airflow velocity. This is attributed to the fact that the electrons with variable horizontal distance from the electron to the plate electrode center are subjected to different electric field forces, resulting in different influences of high-speed airflow on them. These results are of engineering and theoretical significance for insulators used in high-speed railways.

Investigation of the performance of dual-layered omniphobic electrospun nanofibrous membranes for direct contact membrane distillation

Direct contact membrane distillation (DCMD) is a viable one-stop solution for sustainable seawater desalination and wastewater recovery. In this study, robust dual-layered omniphobic electrospun nanofibrous membranes (ENFMs) were fabricated with a re-entrant architecture and low surface free energy. This was achieved by incorporating hydrophobic mesocellular silica foam (MCF-5) into the top layer, followed by the surface functionalisation with 1 H, 1 H, 2 H, 2 H Perfluorodecyltriethoxysilane to improve the membrane anti-wetting and anti-fouling resistance. The dual-layered ENFMs exhibited a high porosity and a water contact angle ≃ of 143˚ and displayed an excellent vapour flux of ∼ 8.5 Lm−2h−1 and NaCl rejection > 99.99% when tested with synthetic seawater. The long-term desalination of natural seawater revealed that the normalised permeate flux was > 0.98 (NaCl rejection > 99.97%), and a simple water wash could recover the loss of membrane hydrophobicity and performance caused by the membrane scaling. The fabricated ENFMs displayed excellent permeate quality (< 1 ppm organic content and < 30 µS/cm) when evaluated with synthetic wastewater containing pharmaceutical compounds (acetaminophen, diclofenac sodium, ibuprofen and amoxicillin). The dual-layered membranes demonstrated outstanding anti-wetting ability when challenged with increasing concentration of cationic surfactant cetyltrimethylammonium bromide (CTAB 1.5 mM) in saline oily wastewater. The preliminary investigations revealed that these ENFMs hold great potential to be further investigated for enhanced water recovery.

Improving surface performance of silicone rubber for composite insulators by multifunctional Nano-coating

Composite insulator is an important component of outdoor insulation systems. It works in complex environments and faces a series of problems such as surface contamination, loss of hydrophobicity, and accumulation of surface charges, which may eventually lead to flashover. Aiming to solve these problems in a simple and scalable method, we propose a multifunctional nano-coating based on SiO2/PDMS/EP. By the combination of multiscale structure and low surface energy modification, this coating shows excellent water-repellency performance, a large contact angle greater than 160° and a small rolling angle near 0° are achieved on coated silicone rubber, which enables the surface with excellent self-cleaning performance. Benefiting from the multiscale roughness, the heat transfer is inhibited by the reduced contact area, which further slows down the icing process on coated silicone rubber. The de-icing force on coated silicone rubber is also smaller than that on pristine silicone rubber. This coating also introduces many shallow traps to the surface, which is beneficial to the fast surface charge dissipation in a short time. Besides, the high water-repelling ability can promote the droplet to roll away under the action of electrical field force, which alleviates the electrical distortion caused by the droplets. As a result, the wet flashover voltage of coated silicone rubber is 60% higher than that of pristine silicone rubber. This multifunctional coating is a facile, scalable, and effective approach to improving the comprehensive surface performance of insulators.

AC Corona Degradation of Silicone Rubber Nanocomposites at Low Air Pressure

Corona discharges get accelerated at low air pressure conditions leading to severe aging of the polymeric housing material, eventually causing the failure of the insulator. In this article, the effect of ac corona on different silicone rubber (SiR) micro- and nanocomposite samples at low pressure is studied. Micro alumina trihydrate (ATH), nano-titanium dioxide (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), and nano-silica are used as filler materials in varying concentrations. This article compares the filler materials for nanocomposite preparation based on their performance in low-pressure conditions. It is observed that the decrease in pressure results in increased corona discharges and loss of hydrophobicity in the samples. The formation of carboxylic acid is evident from the Fourier transform infrared spectroscopy (FTIR) for the treated samples. The performance of silica nanocomposite with 5 wt% loading is better than the silica nanocomposite with 3 wt% loading. Crack width, surface roughness, and physicochemical changes were significantly reduced in silicone dioxide filled SiR (SSR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5%</sub> ) when compared to other silica and TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -filled samples at low pressure. The SiR samples filled with 5 wt% nano-silica perform better in terms of resisting corona-induced degradation at low pressure.

Property evolution of gas diffusion layer and performance shrink of fuel cell during operation

The last decade has seen a renewed emphasis on proton exchange membrane fuel cells. As an essential component in proton exchange membrane fuel cells, gas diffusion layer assumes significant responsibility on water management, as well as on the performance and durability of proton exchange membrane fuel cells. However, researchers have not determined what is the relationship between gas diffusion layer characteristic evolution and the mass transport shrink in proton exchange membrane fuel cells during operation. The objective of this study is to investigate how the property of the gas diffusion layer evolves during cell operation and its relationship with the mass transport of the stack. The results showed that the hydrophilicity of the gas diffusion layer surface and bulk phase increased obviously after the endurance test. The loss of hydrophobic agents and the exposure of hydrophilic surfaces are mainly responsible for this phenomenon. In addition, the structural collapse severely damages the mechanical strength of the gas diffusion layer and thus hinders the electrical conductivity and mass transfer capability of the gas diffusion layer. Loss of hydrophobicity and mechanical strength cause a serious decline in the performance of proton exchange membrane fuel cells.

Interfacial Properties and Antioxidant Activity of Whey Protein-Phenolic Complexes: Effect of Phenolic Type and Concentration

Whey protein is a common food additive for enhancing product stability and texture, while phenolics are considered food antioxidants. As a consequence, combining whey protein with phenolics is an effective way to improve protein functionality while also maintaining polyphenol bioactivity. Herein, the functional properties and antioxidant activity of whey protein modified with various types and concentrations of oxidized phenolic compounds, including gallic acid (OGA), ferulic acid (OFA), and tannic acid (OTA), were studied. In general, the modified whey protein had a decrease in free amino content, but an increase in total phenolic content. Whey protein modified with 5% OTA showed the highest total phenolic content and the lowest free amino content. Modification of whey protein with OTA and OGA resulted in a loss of surface hydrophobicity in contrast to whey protein modified with OFA. However, no significant difference in surface activity including foam and emulsion properties in the whey protein with/without modification was observed. The modified whey protein had an increase in antioxidant activity when compared with that of the control.

Power evolution of fuel cell stack driven by anode gas diffusion layer degradation

Recent research has revealed that gas diffusion layer degradation has a crucial effect on fuel cell stack power density evolution. There have been several investigations focused on the influence of cathode gas diffusion layer degradation on stack performance. However, the degradation behavior and contribution of the anode gas diffusion layer on stack output power remain to be studied. Here, the 1000 h durability test of a stack was conducted under the New European Driving Cycle condition, and the effect of anode gas diffusion layer failure on the stack output power was evaluated. Carbon corrosion is the main attenuation characteristic of the anode gas diffusion layer, which significantly reduces its mechanical strength, and decreased the support capacity of the anode gas diffusion layer. Moreover, carbon corrosion also leads to exposure of new hydrophilic surfaces, reducing the hydrophobicity of the gas diffusion layer. In addition, the loss of hydrophobic agents is also one of the main characteristics of anode gas diffusion layer attenuation, which is the main reason for hydrophobicity loss. The decreased hydrophobicity will significantly improve the water retention capacity, and reduce the back diffusion of cathode water. As a result, mass transfer resistance will increase at a high current density. In conclusion, we verified the crucial impact of anode gas diffusion layer on cell output power density, and provide a new idea for the stack power attenuation investigation.

Influence of corona discharge on the hydrophobic behaviour of nano/micro filler based silicone rubber insulators

Silicone rubber is one of the most used outdoor insulation materials in the last few decades due to its improved performance in contaminated and humid conditions. The improved performance of silicone rubber insulators is due to their hydrophobic nature, however, the organic nature of silicone molecules makes them vulnerable to ageing and degradation. This paper aims at investigating the loss and recovery of hydrophobicity of four different silicone rubber micro/nanocomposites exposed to corona discharge. The samples were exposed to corona discharge generated by pin-plate electrode configuration under AC stress. A series of tests were performed to observe the impact of different electrode-sample gaps and for various periods of corona exposure. The hydrophobicity of samples was measured pre and post corona exposures at various intervals up to 72 h. This time could confirm the hydrophobicity recovery process. Numerical simulations were also performed in COMSOL Multiphysics to investigate the electric fields along the sample surface at different electrode gaps. Experimental results showed that samples recovery time was proportional to the duration of exposure to corona discharge and inversely proportional to the electrode-sample gap. Among all, samples with 2.5% nano-silica as additive showed better hydrophobicity recovery. Simulation results showed that an increase in electrode gap resulted in decreased electric field intensity, hence supporting the experimental outcomes.

Targeted Synthesis of Anti‐Hydrolysis 2D‐ZIF Laminates with Super‐Hydrophobic Transport Channels via In Situ Phase Transition Strategy

AbstractThe design flexibility in the crystalline structure and surface wettability make the zeolitic imidazolate frameworks (ZIFs) an excellent platform for task‐specific applications. However, the key challenge lies in the precise modulation of transport channels, which still suffers from slow diffusion kinetics in nanopores and the loss of hydrophobicity during long‐term operation. Here, a facile structural directing method to render conventional 3D polyhedrons to well‐controlled ZIF nanoplates, and further to super‐hydrophobic laminated material by an in situ phase transition strategy is reported. As exemplified in water transport devices, the integrated ZIFs laminate shows an exceptional anti‐hydrolysis property and super‐hydrophobic transport channels, which warrant remarkable structural stability at fully wet conditions for a time period of at least 3 months, even under acidic conditions and boiling water for 24 h. The simple transformation strategy paves the way for fabrication and regulation of coordinated structures where hydrophobic transport channels are required, and opens a new opportunity for the smart design of advanced structures for water treatment under harsh environments.

Effects of ferulic acid on the oxidation stability and nitrozation of myofibrillar proteins under oxidative stress

This study investigated the effects of ferulic acid (FA) on the oxidative stability and nitrozation of porcine myofibrillar proteins (MPs) under oxidative stress. The addition of FA significantly (P < 0.05) inhibited the formation of carbonyl and dityrosine, and reduced the sulfhydryl and free amine content compared with the oxidized MPs. Moreover, FA intensified oxidation-initiated loss of surface hydrophobicity and α-helix conformation, and enhanced protein cross-linking. A progressive quenching of MP endogenous fluorescence intensity was observed with the increase of FA concentration, and the emission wavelength showed a slight red shift. Beside, the addition of FA significantly eliminated sodium nitrite and almost completely inhibited the formation of 3-nitrotyrosine (3-NT) and N-nitrosodimethylamine (NDMA) at 200 μmol/g. Principal component analysis indicated that there were positive correlations between protein oxidation variables (carbonyl, dityrosine and surface hydrophobicity) and nitrozation indexes (3-NT and NDMA), as well as between 3-NT and NDMA. These results suggest that FA could suppress the nitration via controlling MP's oxidation.

Study on Corona Aging Characteristics of Silicone Rubber Material under Different Environmental Conditions

In this article, a silicone rubber-based composite material is selected as the test sample, and a 100-h corona aging test is conducted under different environments using multiple pin-plate electrodes to study the corona discharge characteristics of pin-plate under different humidity, salt fog, and haze environments. The corona aging characteristics of silicone rubber material are analyzed by the static contact angle, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The results show that, with the increase in the relative humidity (RH), the frequency and energy of corona discharge increase. The discharge frequency under a haze environment is small, but the number and amplitude of the positive half-cycle pulse are larger. With the increase in RH and the deterioration of the environment, the oxidation degree and hydrophobicity loss rate of the material surface are accelerated, and the material surface damage is also aggravated. The aging characteristics of silicone rubber have a positive correlation with the content of water molecules in the air, some hydrophilic -OH, and acidic -COOH appear on the material surface, leading to the insulation performance decrease. As the aging of silicone rubber deepens, its equivalent transverse relaxation time drop increases, the number of H atoms that become low bond energy state inside increases, and the resistance to corona aging decreases. The results of this article can provide some reference for the evaluation, diagnosis, and production of composite insulators in different regions.

Impact of natural and artificial ageing on the properties of multilayer external wall thermal insulation systems

Multilayer external wall thermal insulation systems are widely used in new constructions and for the retrofitting of building façades. Despite the increasing use as constructive solution, significant anomalies have been frequently identified on these systems only few years after their application, raising questions on their long-term durability. This paper focuses on the effects of one-year natural ageing and artificial ageing through hygrothermal cycles (heat/rain and heat/cold) on the water performance (capillary water absorption and drying kinetics), bio-susceptibility (mould development) and surface properties (colour, gloss, and roughness) of four multilayer external wall thermal insulation systems (three ETICS and a thermal rendering system). Results showed a significant loss of surface hydrophobicity after ageing. Considering the 24 h water absorption results, an increase up to 73% and 432% was obtained for the naturally and artificially aged systems, respectively, and when compared to the reference unaged systems. The drying kinetics was affected by ageing, with increases of the drying resistance ranging between 47% and 122% after artificial ageing. Traces of mould growth were observed on the artificially aged systems; however, no growth was detected on either the unaged or the one-year naturally aged systems. Substantial colour change for all systems after ageing was observed, confirming aesthetic alteration. Results contribute towards the development of implemented artificial ageing protocols, as well as for the delivery of multilayer thermal systems with enhanced performance and durability.

Failure behavior of gas diffusion layer in proton exchange membrane fuel cells

Past studies exhibit that the performance constancy of proton exchange membrane fuel cells relate to the multiphase transport of mass, heat, and electricity in the cell, a critical of which is the gas diffusion layer. However, there is little effort devote to the gas diffusion layer degradation mechanism in a real fuel cell stack. In this study, the degradation mechanism of a commercial gas diffusion layer is investigated after the durability test of a 1 kW fuel cell stack. The results confirm that the degradation of the gas diffusion layer makes a great contribution to the membrane electrode assembly regression. The dissolution of non-graphitized carbon and polytetrafluoroethylene leads to structural damage and hydrophobicity loss of microporous substrate. In addition, the strength decay behavior of carbon fiber is detected. These degradations lead to the loss of support capability and hydrophobicity of gas diffusion layer. The combined effect of these factors leads to a decrease in the effective gas transfer path of the gas diffusion layer under high current density, which leads to a decline in fuel cell performance. This study provides an essential basis for the design of a high-durability gas diffusion layer for proton exchange membrane fuel cells.

In vitro biodegradation of low-density polyethylene by soil microorganisms

The accumulation of recalcitrant plastics in the environment, particularly polyethylene, is a major threat to the ecology. Among the different kinds of polyethylene, low-density polyethylene (LDPE) is the most widely used polyethylene. The goal of this work was to isolate and discover a powerful polyethylene degrading microbial strain from plastic waste disposal soil. The bacterial and fungal strains were isolated by enrichment technique and were identified based on the morphological and biochemical characteristics. Further, they were screened individually for their lowdensity polyethylene (LDPE) degrading efficiency by in vitro biodegradation assay. The efficiency of the potent strain to colonize on the LDPE surface and its biodegradation ability were investigated. The degraded products of low-density polyethylene were analysed by FTIR after the biodegradation study which was conducted for a long incubation period by inoculating the selected bacterial strain in synthetic medium (SM) with LDPE as the carbon source. Totally six different bacterial and five different fungal strains were isolated from the polluted soil. Among the bacterial strains, the JSB2, JSB3 and JSB4 and among the fungal strains, JSF1, JSF3 and JSF4 showed maximum growth, more cell surface hydrophobicity and weight loss and they were selected for further studies. The incubation of LDPE films with bacteria and fungi led to the formation of new absorbance bands such as dehydrated dimer of carbonyl group (1720 cm-1), CH3 deformation (1463 cm-1) and C=C conjugation band (862 cm-1). The results inferred that the exogenous addition of these microbes to LDPE contaminated soil causes an enhanced degradation. Among the microbial isolates, Bacillus species showed high degradation.

Aging characteristics and self-healing properties of laser-textured superhydrophobic silicone rubber for composite insulators

The aging characteristics of laser-treated superhydrophobic silicone rubber surfaces was investigated through accelerated aging tests. It indicated that the superhydrophobic surfaces have excellent anti-aging properties, which is manifested in that even after aging for 1000 h, the contact angles of the superhydrophobic surfaces remain above 140o. The loss of hydrophobicity was caused by defects in the surface microstructures, a decrease in the hydrophobic ―CH3 groups, and an increase in the hydrophilic ―OH groups on the surfaces. To avoid the decrease in the hydrophobicity of the prepared superhydrophobic surface, a simple and efficient heat treatment method was adopted to restore its hydrophobicity. After heat treatment at 200°C, the rolling angle of the aged surface was restored to 4.6o with a contact angle of 161.5o. This recovery is mainly attributed to the decrease in the content of the ―OH on the rubber surface during the heat treatment. The results also show the sample surface irradiated with a laser fluence of 10.0 J/cm2 has better anti-aging performance and self-healing properties due to the larger particles and a more distinct micro-nano hierarchical structures, providing a smaller actual illumination area and a larger heating area in the aging and heat treatment process.

Accelerated stress testing of PUREBLACK® carbon-based gas diffusion layers with pore forming agent for proton exchange membrane fuel cells

Gas diffusion layer (GDL) configurations containing PUREBLACK® and VULCAN® carbons with 30 wt % polyethylene glycol as pore forming agent are evaluated under two ex-situ methods of accelerated stress testing (AST), in water and hydrogen peroxide (30%), for 1000 and 24 h, respectively. The samples are characterized via contact angle, scanning electron microscopy (SEM), porosity and pore size distribution and the fuel cell performance and durability are also evaluated, before and after the ASTs. Contact angle and SEM demonstrate extensive degradation impact on VULCAN® carbon, especially in hydrogen peroxide, with cracked surface due to carbon corrosion and wash-off, complete hydrophobicity loss, along with porosity increase. The fuel cell performance is evaluated at 60 and 100% RH at 70 °C, using O2 and air as oxidants, and the degraded VULCAN® carbon-based GDLs after the ASTs, result in significant performance loss and durability in air (~20% after 50 h) test shows non uniform gas distribution to the catalyst layer after ~30 h of continuous operation under constant current density 600 mA.cm−2, especially under high RH conditions. On the other hand, PUREBLACK®-based GDLs demonstrate superior durability in air (~12% after 50 h), possibly attributed to its graphitized carbon structure, as evident from the stable durability for 50 h.

Durable and Flexible Hydrophobic Surface with a Micropatterned Composite Metal-Polymer Structure.

Hydrophobic metallic surfaces have attracted much academic and industrial interest due to their promising applications in various fields. Typically, hydrophobicity in metallic materials can be realized by micro/nanostructures and chemical treatment. However, both fragile rough surfaces and low-surface-energy fluorinated silanes are prone to wear and abrasion, leading to the loss of hydrophobicity. In this experiment, we demonstrated a facile and potentially low-cost methodology to fabricate hydrophobic surfaces by integrating a mechanically durable nickel skeleton with an interconnected microwall array filled with hydrophobic poly(tetrafluoroethylene) (PTFE). The interconnected metal frames prevented the removal of the hydrophobic material by abradants, and good hydrophobicity was preserved after more than 1000 cycles of linear abrasion under a local pressure of ∼0.12 MPa. The fabricated surfaces exhibited enhanced anti-icing properties with water droplets compared to unprocessed nickel surfaces. The prepared surfaces also showed superior flexibility. No obvious fracture was observed even after 300 cycles of buckling while the hydrophobic performance was still maintained. The surfaces designed here could provide effective guidance to manufacture large-area surfaces in nickel and other metallic materials that require flexibility, hydrophobic properties, and anti-icing functions for harsh applications.

Hydrophobic recovery of femtosecond laser processed silicone rubber insulator surfaces

AbstractThis article demonstrates the loss and recovery in hydrophobicity of silicone rubber insulator surface processed by a femtosecond laser. The two stages of the wettability conversion were investigated. First, a rough micro/nano structure was formed on the original hydrophobic sample surface processed by the femtosecond laser, and the water contact angle on the surface was reduced from ~ 110° to a minimum of ~ 35°. This hydrophilicity loss was due to the increase in the hydrophilic OH groups and the reduction of the hydrophobic CH3 groups on the surfaces. Second, the roughened samples were stored in a natural ambient environment. Over a certain storage time, the surface hydrophobicity recovered gradually and evolved into a superhydrophobic state. It was found that the migration of low molecular weight cycle and/or linear siloxane oligomers resulted in the recovery of the hydrophobicity property. Coupled with the increase of surface roughness caused by laser irradiation, the further evolution of the hydrophobicity was promoted. Moreover, the higher temperature accelerates the recovery of the surface hydrophobicity. The research on the conversion mechanism of the wettability on the silicone rubber insulator surface processed by femtosecond laser is of great significance for improving its reliability in practical applications.