Polyurethane Surface Research Articles

AFM Nanoindentation of Stiff Inhomogeneous Layer onPolymeric Substrate.

Analysis of indentation data of heterogeneous material, in particular, layer on an elastic substrate requires information about the contact area that is essential for calculating mechanical properties. The actual shape of the AFM-tip is not described by simple body of revolution. In this work, the indentation of a stiff layer on a hyperelastic substrate by a truncated conical tip is studied using finite element methods. The size of the tip, elastic modulus, and thickness of the layer are varied. The obtained model dependences of loading and contact area versus the depth of indentation are used in analysis of the experimental data of AFM indentation of stiff inhomogeneous nanolayers of polyurethane surface. Thickness and elastic modulus of the layers, fracture properties of the surface are studied. The obtained results can find application in the study of mechanical properties and fracture toughness of thin flexible films on an elastic substrate.

Optimization of Electromagnetic-Wave Reflectivity Performance of Electromagnetic Shielding Yarn Prepared by Evaporation-Induced Sintering of Ga60.5In25Sn13Zn1.5 Alloy with Nanosilicates.

Electromagnetic interference (EMI) shielding textiles have received widespread attention, and liquid metal (LM) shows superiority in flexible and deformable electronics. Here, we introduce a novel method using nanosilicates to help sinter LM through capillary evaporation, resulting in strong adhesion to substrates. By adjustment of the amount of nanosilicates, flexible EMI shielding yarns are created using dip-coating and curing processes. The sintered LM tightly adhered to the undulating and uneven surfaces of polyurethane (PU) yarns. The as-fabricated ION/LM@PU ("ION" is abbreviation of "ionogel") has strong EMI shielding and low EM-wave reflection due to the high electrical conductivity of the LM layer and good impedance matching of P(AAm-co-AA) ionogel. The addition of an ionogel enhances EM-wave absorption and strengthens interfacial polarization, making it an effective green EMI shielding yarn for reducing secondary reflection pollution. ION/LM@PU exhibited high total electromagnetic interference shielding effectiveness (EMI SET) (∼56 dB), low reflected power coefficient (R) (∼0.153), high impedance matching (|Zin/Z0| ≈ 0.660), high tensile strength (∼23.75 MPa), and high elastic recovery (∼0.92 at 10th stretch-release cycle). The EMI shielding mechanism of ION/LM@PU ± 60° is composed of reflective loss and absorption loss (including multireflective loss, conduction loss, dipole polarization loss, and interfacial polarization loss).

Mechanically robust, self-healing and stretchable electromagnetic shielding materials based on multi-component dynamic bonded polyurethane elastomer

Stretchable self-healing electromagnetic interference (EMI) shielding materials can automatically restore their original performance after mechanical damage, and can still maintain over 20 dB EMI shielding effectiveness (EMI SE) under tensile state. In this work, a series of highly stretchable self-healing polyurethane elastomer PUBNS-X was prepared by introducing dynamic disulfide bonds, boronic ester bonds and boron-nitrogen coordination (B-N) on the polyurethane main chain. It was found that B-N coordination significantly increased the elongation at break and the tensile strength. The high dynamic reversibility of boronic ester, disulfide bond and B-N coordination bond synergistically endowed PUBNS-X with excellent temperature-triggered self-healing properties. The mechanical properties of PUBNS-X can be restored to more than 90 % at 60 °C. The pre-assembled silver nanowires (AgNWs) conductive network was then introduced into the polyurethane surface by taking advantage of the fluidity of the dynamically bonded polyurethane backbone to obtain a series of stretchable self-healing electromagnetic shielding composites (AgNWs/PUBNS-Y). The results showed that the EMI SE of AgNWs/PUBNS-Y can reach ∼55 dB, and the conductivity can be restored to 82 % of the original value after healing at 60 °C. The investigation of the electromagnetic interference shielding performance of composites under different strains showed that the EMI SE of AgNWs/PUBNS-3 can still maintain 20 dB under 90 % strain. These composites will have broad potential applications in the fields of flexible wearable electronic products, bionic intelligent materials and soft robots.

Mechanically robust and durable polyurethane-based superhydrophobic coating containing silica nanoparticles derived from hydrothermal assisted sol–gel method

In the current study, a suspension of hydrothermal assisted sol–gel synthesised superhydrophobic silica nanoparticles (h-SNPs) are sprayed over apartially cured polyurethane (PUR) surface on aluminium substrate. The surface exhibited superhydrophobic (SH) property with a water contact angle of 166 ± 2° and awater sliding angle of < 5°. X-ray diffraction study confirmed the formation of amorphous silica nanoparticles. The particle size determined by field emission scanning electron microscope is about 19–21 nm. The roughness of the coating is 3.5 µm as characterised using a surface profilometer. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy investigations indicated the presence of urethane linkages from PUR and siloxane stretching from h-SNPs. The adhesion of the coating tested with a cross-hatch cutter as per ASTM D3359 shows a rating of 5B. The coating qualified mandrel bend test conducted according to ASTM D255. No cracks are observed at the deformed areas and water drops roll off the surface, demonstrating the integrity of the coating and its superhydrophobicity. The coating exhibits high robustness as evident from sandpaper abrasion and tape peel tests. When compared to superhydrophobic polyurethane (SH PUR) coating developed using commercial silica as reported in our previous work, the developed h-SNPs coating is much more durable as confirmed by accelerated weathering test and anti-icing test. The SH coating also exhibits superhydrophobicity even after 200 h of accelerated weathering test and 16 de-icing cycles. The coating withstands 15 days of water immersion and also displays self-cleaning property.

Strain Sensing Enhancement of 3D-printed Polyurethane through Surface Deposition of Carbon Black

Strain sensors for wearable electronics function by identifying mechanical deformations and translating into electrical signals. For optimal performance, electrical conductivity, electrical sensitivity, and flexibility are major properties of strain sensors. Polyurethane (PU) shows promise for custom strain sensors due to its high flexibility. Additionally, using digital light processing (DLP) 3D printing to shape PU is suitable for detecting body movements. Therefore, the aim of this study is developing 3D-printed PU to strain sensing devices, utilizing the surface coating method on 3D-printed PU with carbon black (CB) and polydimethylsiloxane (PDMS) to fabricate the (PDMS+CB)/CB/PU strain sensor. The conductive network of CB enhances sensitivity, while PDMS is incorporated to act as an adhesive for the durability of CB on the PU surface. The results of the experiment reveal a gauge factor of 6.04 with range from 1 to 10% elongation. The strain sensor of this study has high potential to use for strain sensing technology and is capable of detecting small body movements.

Constructing a catalytical NO-generation coating on a polyurethane surface to enhance hemocompatibility and promote endothelial cell growth

Polyurethanes (PU) is widely applied in the blood-contact biomaterials. However, its biocompatibility still cannot meet the requirements for long-term service. In this work, a polydopamine (PDA) layer was first prepared on the PU surface, and then an anticoagulant polymer with an endothelial glycosaminoglycan-mimicking structure capable of catalyzing the release of nitric oxide (NO) gas molecules 6-arm-poly (ethy1ene glycol)-Heparin-Selenocystamine (PEG-Hep-SeCA) was grafted on the PDA-modified PU surface to construct a bioactive coating with the capacity to catalyze the release of NO from the endogenous donors. The findings indicated that the modified PU surfaces had excellent hydrophilicity, selective albumin adsorption as well as good blood compatibility and endothelial cell growth properties. The hemocompatibility and endothelial cell growth were further significantly improved in the case of catalytic NO generation. Therefore, the surface modification strategy of this study can significantly improve the biocompatibility of PU and thus lay the foundation for future clinical applications of medical polyurethane.

Liquid metal induced segregated-like electromagnetic shielding composites with excellent photothermal conversion and strain sensing capacities

The development of multifunctional electromagnetic interference (EMI) shielding materials has garnered significant attention, yet achieving flexible composites that integrate EMI shielding, thermal conductivity, and other functionalities under low filler loading remains a challenge. This study presents a novel flexible composite with segregated structure prepared via a simple co-mixing and hot-pressing method. By selectively distributing conductive Liquid metal (LM) and Multi-wall carbon nanotube (CNT) on the surface of Polyurethane (TPU) particles, a continuous and compact conductive network is successfully constructed, enabling the attainment of a high EMI shielding effectiveness of 80.2 dB and a thermal conductivity of 4.8 W m−1 K−1 even at low LM loadings. Furthermore, the composite exhibits low-voltage-driven Joule heating performance, excellent photothermal conversion efficiency, and promising potential for wearable sensor applications. The combination of these outstanding properties highlights the great potential of LM-based composites for next-generation wearable devices.

Surface Immobilization of Oxidized Carboxymethyl Cellulose on Polyurethane for Sustained Drug Delivery.

Polyurethane (PU) has a diverse array of customized physical, chemical, mechanical, and structural characteristics, rendering it a superb option for biomedical applications. The current study involves modifying the polyurethane surface by the process of aminolysis (aminolyzed polyurethane; PU-A), followed by covalently immobilizing Carboxymethyl cellulose (CMC)polymer utilizing Schiff base chemistry. Oxidation of CMC periodically leads to the creation of dialdehyde groups along the CMC chain. When the aldehyde groups on the OCMC contact the amine group on a modified PU surface, they form an imine bond. Scanning electron microscopy (SEM), contact angle, and X-ray photoelectron spectroscopy (XPS) techniques are employed to analyze and confirm the immobilization of OCMC on aminolyzed PU film (PU-O). The OCMC gel incorporates Nitrofurantoin (NF) and immobilizes it on the PU surface (PU-ON), creating an antibacterial PU surface. The confirmation of medication incorporation is achieved using EDX analysis. The varying doses of NF have demonstrated concentration-dependent bacteriostatic and bactericidal effects on both Gram-positive and Gram-negative bacteria, in addition to sustained release. The proposed polyurethane (PU-ON) surface exhibited excellent infection resistance in in vivo testing. The material exhibited biocompatibility and is well-suited for biomedical applications.

Foreign Body Reaction to Ion-Beam-Treated Polyurethane Implant.

All artificial materials used for implantation into an organism cause a foreign body reaction. This is an obstacle for a number of medical technologies. In this work, we investigated the effect of high-energy ion bombardment on polyurethane for medical purposes and the reaction of body tissues to its insertion into the mouse organism. An analysis of the cellular response and shell thickness near the implant showed a decrease in the foreign body reaction for implants treated with high-energy ions compared to untreated implants. The decrease in the reaction is associated with the activation of the polyurethane surface due to the formation on the surface layer of condensed aromatic clusters with unbonded valences on the carbon atoms at the edges of such clusters and the covalent attachment of the organism's own proteins to the activated surface of the implant. Thus, immune cells do not identify the implant surface coated with its own proteins as a foreign body. The deactivation of free valences at the edges of aromatic structures due to the storage of the treated implant before surgery reduces surface activity and partially restores the foreign body response. For the greatest effect in eliminating a foreign body reaction, it is recommended to perform the operation immediately after treating the implant with high-energy ions, with minimal contact of the treated surface with any materials.

Molecular dynamics simulation of water permeation mechanism in polymer grouting material

Polyurethane (PU) grouting materials are commonly used in infrastructure trenchless rehabilitation projects and are frequently exposed to water environments. However, the underlying microscopic mechanism of polymer damage caused by water infiltration has not been systematically investigated. In this paper, we employed molecular dynamics (MD) simulation to explore the wetting behavior of water on the PU surface and the permeation behavior of PU under pressure. The results showed that when sufficiently high water pressure is applied, PU deforms and creates voids. Subsequently, water molecules begin to penetrate the interior of the PU. For PU models with thicknesses of 10 Å, 15 Å, and 20 Å, penetration behavior was observed at water pressures of 189 MPa, 256 MPa and 314 MPa, respectively. Moreover, with PU models of identical thickness, the depth of water molecules penetration and the volumetric water content of the PU increased with rising water pressure. Furthermore, it was observed that PU has many small interatomic pores in its free state. Under the influence of water, distribution of these pores deviates from a normal distribution and becomes irregular. These findings provide valuable insights into the microscopic mechanism underlying infiltration damage of PU grouting materials at the molecular level.

Argatroban- and copper-modified polymers with improved thromboresistance and antimicrobial properties

This paper describes a novel approach the development of biocompatible polyvinyl chloride (PVC) and polyurethane (PU) polymers, modified with copper (II) ions followed by the immobilisation the thrombin inhibitor argatroban (AG) using dopamine chemistry. The surface loading of the immobilised AG was 6.06 µg cm−2 on PVC and 6.66 µg cm−2 on PU, confirmed by FTIR and inhibitor concentration measurements. Both AG/Cu-modified polymers produced NO by catalytically decomposing S-nitrosothiol, reaching NO levels in plasma of 0.59 × 10–10molcm-2min-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{mol} \\, {\ ext{cm}}^{-2} \\, {\ ext{min}}^{-1}$$\\end{document} for AG/Cu-PVC and 0.51 × 10–10molcm-2min-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{mol} \\, {\ ext{cm}}^{-2} \\, {\ ext{min}}^{-1}$$\\end{document} for AG/Cu-PU, matching endothelial cell-produced physiological levels. This modification improved the haemocompatibility of the polymers through thrombin inhibition and reduced platelet aggregation and adhesion. Additionally, both modified polymers inhibited Staphylococcus aureus adhesion, growth and viability, confirming their acquired antibacterial properties. Antibacterial activity against Escherichia coli was also observed. These results demonstrate that modifying PVC and PU surfaces with copper (II) and AG produced materials with dual antithrombotic and antibacterial functions.Graphical abstract

The effects of submicron-textured surface topography on antibiotic efficacy against biofilms.

Submicron-textured surfaces have been a promising approach to mitigate biofilm development and control microbial infection. However, the use of the single surface texturing approach is still far from ideal for achieving complete control of microbial infections on implanted biomedical devices. The use of a surface topographic modification that might improve the utility of standard antibiotic therapy could alleviate the complications of biofilms on devices. In this study, we characterized the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa on smooth and submicron-textured polyurethane surfaces after 1, 2, 3, and 7 days, and measured the efficacy of common antibiotics against these biofilms. Results show that the submicron-textured surfaces significantly reduced biofilm formation and growth, and that the efficacy of antibiotics against biofilms grown on textured surfaces was improved compared with smooth surfaces. The antibiotic efficacy appears to be related to the degree of biofilm development. At early time points in biofilm formation, antibiotic treatment reveals reasonably good antibiotic efficacy against biofilms on both smooth and textured surfaces, but as biofilms mature, the efficacy of antibiotics drops dramatically on smooth surfaces, with lesser decreases seen for the textured surfaces. The results demonstrate that surface texturing with submicron patterns is able to improve the use of standard antibiotic therapy to treat device-centered biofilms by slowing the development of the biofilm, thereby offering less resistance to antibiotic delivery to the bacteria within the biofilm community.

Isolation, identification and screening of Polyurethane polymer degrading microbe isolated from contaminated site

The objective of this research was to isolate soil-based bacteria that may destroy polyurethane (PU). PU plays a crucial role in many parts of our daily life. Polyurethanes are a significant and adaptable group of synthetic polymers utilized in a wide range of industrial, automotive and medical sectors. Due of its widespread use and challenges in recycling or reusing, PU primarily becomes garbage. PU has been observed to be degraded by a variety of bacteria and fungi. The objective of this study was to isolate polyurethane degrading microbes from the soil sample. Two bacteria Bacillus subtilis and Pseudomonas aeruginosa and three fungi Aspergillus versicolor, Aspergillus fumigatus and Aspergillus Niger, were isolated and identified from the soil sample based on morphological and biochemical characteristics. In this study, the fungus Aspergillus versicolor shows the high degradation percentage on polyurethane film. Scanning electron microscopy and ATR-FTIR were used in this study to evaluate the surface and chemical alterations of PU.

Electrophoretic deposition of TiO2 nanotubes and antibiotics on polyurethane coated stainless steel for improved antibacterial response and cell viability

In the quest for advancing the performance of metallic implants, surface modification emerges as a pivotal strategy to mitigate ion depletion, enhance the host's biological response, and exhibit anti-microbial behavior with reduced cytotoxicity. In this study, we developed a non-traditional electrophoretic deposition (EPD) hybrid coating for medical-grade stainless steel 316 L (SS316L) surfaces covered with a segmented polyurethane (SPU). These coatings are composed of anatase TiO2 nanotubes (TiO2_A), and antibiotics (nisin N or gentamicin G). We characterized the modified metals using FTIR and Raman spectroscopy, contact angle measurements, AFM, TGA, SEM-EDX, as well as assessing their antimicrobial response and cell cytotoxicity. The results demonstrate the formation of porous surfaces with embedded nanotubes and antibiotics within and on the polyurethane surfaces. Samples with SPU+ TiO2_AG EPD exhibited superior coverage, antimicrobial properties, and enhanced viability compared to cases where only particles or antibiotics were coated individually. Additionally, samples of SPU+ TiO2_AN EPD displayed favorable hydrophilicity and suitable cytotoxicity. Therefore, the synergistic effect of nanoparticles and antibiotics positively influences the functionality of the coating.

Mechanical-Enhanced and Durable Zwitterionic Hydrogel Coating for Inhibiting Coagulation and Reducing Bacterial Infection.

Blood-contact medical devices are indispensable for clinical interventions, yet their susceptibility to thrombosis and bacterial infections poses substantial risks to treatment efficacy and patient well-being. This study introduces a polysulfobetaine/alginate-CuII (SAC) zwitterionic hydrogel coating on polyurethane (PU) surfaces. This approach retains the superhydrophilic and antifouling nature of pSBMA while conferring the antibacterial effects of copper ions. Meanwhile, the copper alginate network intertwines with the polysulfobetaine (pSBMA) network, enhancing its mechanical properties and overcoming inherent weaknesses, thereby improving coating durability. Compared to the substrate, the SAC hydrogel coating significantly reduces thrombus adhesion mass by approximately 81.5% during extracorporeal blood circulation and effectively prevents bacterial biofilm formation even in a high-concentration bacterial milieu over 30 days. Moreover, the results from an isolated blood circulation model in New Zealand white rabbits affirm the impressive anticoagulant efficacy of the SAC hydrogel coating. The findings suggest that this hydrogel coating and its application method hold promise as a solution for blood-contact material surface modification to address thrombosis and bacterial biofilm formation simultaneously.

In Vivo Comparison of the Efficacy and Duration of Local Antibiotics on Smooth, Textured and Polyurethane Implant Surfaces.

Capsular contracture is one of the most common complications after breast surgery involving silicone implants. The most likely cause of this condition is biofilm formation. In this study, the efficacy of local antibiotherapy against biofilm formation on implant surfaces was investigated. Thirty-six rats were divided into six groups. Three pockets were created on the dorsum of each rat, and 1 × 2cm implant surface samples from smooth, polyurethane and textured implants were randomly placed into pockets. All samples were inoculated with staphylococcus epidermidis. In groups 1-2-3, inoculated samples were placed into the pockets and removed after 1, 6 and 24h, respectively. In groups 4-5-6, inoculated samples immersed with rifamycin were placed and removed after 1, 6 and 24h, respectively. Bacterial load was measured with plate count method. Bacterial load was lower in groups 4-5-6 than in groups 1-2-3 (p < 0.05). In groups 4-5-6, bacterial load was lower for polyurethane than for textured surfaces at all time points (1, 6 and 24h; p < 0.05). Again, in groups 4-5-6, bacterial load was lower for smooth than for textured surfaces at 24h (p < 0.05). In groups 4-5-6, bacterial load was lower for polyurethane than for smooth surfaces at all time points, but difference was not statistically significant (1, 6 and 24h; p < 0.05). The results suggest that local antibiotic therapy was effective in reducing the bacterial load on all surfaces. The effectiveness of local rifamycin on the polyurethane surface was higher, and the duration of activity was longer than other surfaces. This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of contents or the online Instructions to Authors www.springer.com/00266 .

Biofilm formation by Listeria monocytogenes from the meat processing industry environment and the use of different combinations of detergents, sanitizers, and UV-A radiation to control this microorganism in planktonic and sessile forms.

This study aimed to evaluate the ability of biofilm formation by L. monocytogenes from the meat processing industry environment, as well as the use of different combinations of detergents, sanitizers, and UV-A radiation in the control of this microorganism in the planktonic and sessile forms. Four L. monocytogenes isolates were evaluated and showed moderate ability to form biofilm, as well as carried genes related to biofilm production (agrB, agrD, prfA, actA, cheA, cheY, flaA, sigB), and genes related to tolerance to sanitizers (lde and qacH). The biofilm-forming isolates of L. monocytogenes were susceptible to quaternary ammonium compound (QAC) and peracetic acid (PA) in planktonic form, with minimum inhibitory concentrations of 125 and 75 ppm, respectively, for contact times of 10 and 5min. These concentrations are lower than those recommended by the manufacturers, which are at least 200 and 300 ppm for QAC and PA, respectively. Biofilms of L. monocytogenes formed from a pool of isolates on stainless steel and polyurethane coupons were subjected to 14 treatments involving acid and enzymatic detergents, QAC and PA sanitizers, and UV-A radiation at varying concentrations and contact times. All treatments reduced L. monocytogenes counts in the biofilm, indicating that the tested detergents, sanitizers, and UV-A radiation exhibited antimicrobial activity against biofilms on both surface types. Notably, the biofilm formed on polyurethane showed greater tolerance to the evaluated compounds than the biofilm on stainless steel, likely due to the material's surface facilitating faster microbial colonization and the development of a more complex structure, as observed by scanning electron microscopy. Listeria monocytogenes isolates from the meat processing industry carry genes associated with biofilm production and can form biofilms on both stainless steel and polyurethane surfaces, which may contribute to their persistence within meat processing lines. Despite carrying sanitizer tolerance genes, QAC and PA effectively controlled these microorganisms in their planktonic form. However, combinations of detergent (AC and ENZ) with sanitizers (QAC and PA) at minimum concentrations of 125 ppm and 300 ppm, respectively, were the most effective.

Wearable skin-like polyurethane devices with variable optical functions

Skin-like wearable devices have great potential in the era of intelligence. In addition to common electronic devices, flexible photonic devices are receiving ever-increasing attention, while intelligent features of devices such as self-healing are also requested. In this work, a smart skin-like wearable photonic device constructed by combining inorganic optical materials and self-healing polyurethanes is reported. Polyurethanes with skin-like modulus are synthesized by mixing chain extender, cross-linker, and hindered phenol AO-70, demonstrating fast self-healing capability (healing efficiency of 99 % within 2 min) and good shape memory effect (shape fixation rate of 90 %). A series of flexible photonic devices are prepared by depositing optical materials on polyurethane surfaces by physical vapor deposition (PVD), with a focus on a photonic device for 1064 nm laser protection. Notably, the device exhibits a spectral recovery rate of 91.76 % after 150 % strain and a spectral recovery rate of 98.13 % after healing in 2 min, indicating superior stretchability and fast self-healing ability. This work provides a new strategy for smart skin-like wearable flexible photonic devices.

An investigation into the effect of UV irradiation and biofilm colonization on adsorption and desorption behavior of polyurethane (PU) microplastics for bisphenol A (BPA)

Recent studies have demonstrated that microplastics (MPs) can act as a transport vector for pollutants in the environment. However, most studies have focused on carbon-carbon backbone polymers, with little known about heteroatom backbone polymers. In this study, polyurethane (PU) MPs were modified by UV irradiation and microorganism colonization to assess the different aging treatments on the interaction behavior (adsorption/desorption) between PU MPs and bisphenol A (BPA). The results of the adsorption kinetics experiment illustrated that the adsorption process of BPA could be described well by a pseudo-second order kinetic equation on both fresh and aged PU MPs. Although fresh PU MPs revealed the highest saturated adsorption capacity, at low BPA exposure concentrations (≤ 100 μg/L) the adsorption capacities for UV aged and biofilm colonized PU MPs were very similar to fresh MPs or even slightly higher than for fresh MPs, the main adsorption mechanisms including H-bonding interactions and π–π interactions. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) investigations suggested obvious physicochemical property changes (e.g., generation of new functional groups, erosion, etc.) after UV irradiation and biofilm colonization. This study also showed that different exposure environments (ultrapure water, artificial seawater, simulated gastric fluid) could affect BPA adsorption/desorption via hydrophobic and electrostatic interaction on PU surfaces. These results further clarify the adsorption mechanisms of BPA on PU MPs that have undergone different aging treatments, and provides a theoretical basis for the assessment of environmental behavior and exposure risks when PU MPs and BPA coexist.

A flexible superhydrophobic thermoplastic polyurethane porous surface with good self-cleaning function prepared by supercritical CO2 foaming

Porous surfaces show great potential for superhydrophobic applications. Supercritical CO2 foaming is a green technology for preparing porous materials, but it is rarely used to prepare porous surfaces due to the non-porous skin caused by the escape of gas. In this study, a porous thermoplastic polyurethane (TPU) surface with dense cell and small cell spacing is prepared by employing bilayer TPU sheet to restrict the escape of gas from surfaces. The influence of the foaming pressure and temperature on the cells of the TPU surface is researched. Furthermore, bimodal cells are obtained by regulating the foaming process and the effect of cell structure on wettability is investigated. Subsequently, a flexible superhydrophobic material with low water-adhesion, mechanical stability, and self-cleaning properties is successfully prepared by modifying fluorinated silica particles on porous TPU surfaces.