Polyurethane Surface Research Articles

Improving hydrophobicity of polyurethane by PTFE incorporation

ABSTRACTA simple and facile method was established of incorporating polytetrafluoroethylene (PTFE) on to polyurethane (PU) to improve hydrophobicity of PU by incorporating low levels of fluorine at a molecular level. Nanocomposites were made by preparing PU in the presence of PTFE using seeded miniemulsion polymerization method. The resulting PTFE/PU nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, differential scanning calorimetric, and thermo gravimetric analysis (TGA). FTIR and TEM indicated changes observed in their structure, size and morphology. The water contact angle of PTFE/PU nanocomposite films increased with increasing amount of PTFE and more on blending with silica nanoparticles but a slight decrease in thermal stabilities of SiO2/PTFE/PU nanocomposites were noticed. The hydrophobicity imparted by PTFE to PU surface was found to be at its best for 1 : 2 PTFE/PU latex film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42779.

Siły i stereometria warstwy wierzchniej poliuretanu po różnych obróbkach skrawania

Siły i stereometria warstwy wierzchniej poliuretanu po różnych obróbkach skrawania

Polyurethane: Stable Cell Phenotype Requires Plasticity: Polymer Supported Directed Differentiation Reveals a Unique Gene Signature Predicting Stable Hepatocyte Performance (Adv. Healthcare Mater. 12/2015).

One major obstacle to the routine deployment of stem cell-derived cells is their instability in culture. On page 1820 David C. Hay and co-workers describe the use of a synthetic polymer surface. The image shows stem cell-derived hepatocytes replated on this polyurethane surface. Importantly the cells express Zonal Occludin (green stain) at the cell surface, which indicates that the cells display elements of polarization. The blue stain is DAPI, which demarks the nucleus.

Bioinspired Blood Compatible Surface Having Combined Fibrinolytic and Vascular Endothelium‐Like Properties via a Sequential Coimmobilization Strategy

Developing surfaces with antithrombotic properties is of great interest for the applications of blood‐contacting biomaterials and medical devices. It is promising to coimmobilize two or more biomolecules with different and complementary functions to improve blood compatibility. However, the general one‐pot strategy usually adopted by previous studies suffers the problems of inevitable competition between diverse biomolecules and uncontrollability of the relative quantities of the immobilized biomolecules. To solve these problems, a new sequential coimmobilization strategy is proposed and applied to fabricate a blood compatible surface. Polyurethane surface is modified with a copolymer, poly(2‐hydroxyethyl methacrylate‐co‐1‐adamantan‐1‐ylmethyl methacrylate), which serves as a linker‐spacer for sequential attachment of two functional molecules, a hexapeptide containing REDV (Arg‐Glu‐Asp‐Val) sequence, and a modified cyclodextrin bearing 7 lysine ligands, through covalent bonding and host–guest interaction, respectively. The resulting surface combines the antithrombogenic properties of the vascular endothelium and the clot lysing properties of the fibrinolytic system. Importantly, neither of the two functions of REDV peptide and lysine is compromised by the presence of the other, suggesting the enhanced blood compatibility. These results suggest a new strategy to engineer multifunctional surfaces by coimmobilization of bioactive molecules having unique functionalities.

Thermal behavior, surface energy analysis, and hemocompatibility of some polycarbonate urethanes for cardiac engineering

The understanding of basic surface properties and the relationships between temperature and the configuration of the polymer surface are the key to further understand the first interaction mechanism of the polymer with the body. To this end, some poly(carbonate tetramethylene ether)urethane (PCEU), poly(carbonate siloxane tetramethylene ether)urethane (PCSiEU), and their 1:1 gravimetric mixture (PCEU/PCSiEU) membranes were prepared. In order to establish the relationships between temperature and the chemical structure of polymer surface, the polyurethane (PU) membranes were analyzed by attenuated total reflectance–Fourier transform infrared spectroscopy. The temperature has a significant influence on these PU surface structures. Surface characteristics such as wettability and surface free energy were also analyzed since the interaction between biomaterials and blood occurs at their interface. The preliminary cytotoxicity screening showed no cytotoxicity of these PU membranes. The PU samples do not accelerate the clot formation mechanisms under the tested conditions. The results suggest that these PU membranes are promising materials for the preparation of cardiovascular scaffolds.

Collagen immobilization on poly(ethylene terephthalate) and polyurethane films after UV functionalization

An attractive alternative method to add new functionalities such as biocompatibility due to the micro- and nanoscaled modification of surfaces is offered by UV-modified polymers. The aim of this study was to evaluate the effect of the UV light functionalization on two polymers, poly(ethylene terephthalate) (PET) and polyurethane (PU) films, by means of atomic force microscopy (AFM), Fourier transform infrared–attenuated total reflectance (FTIR–ATR), and contact angle measurements. Thus, the UV-irradiation activates the polymers surface by breaking some chemical bonds and generation of new functional groups on the surface. This process can be controlled by the irradiation time. The topography provides the formation of superposed ‘nap’ and ‘wall-type’ structures on both untreated and treated samples. The surface parameters were found to depend on the polymer films before and after irradiation. The immobilization of collagen on PET surface was confirmed by X-ray photoelectron spectroscopy measurements and for PU surface was proved by FTIR–ATR. First technique suggests an increase of the nitrogen content at longer UV exposure time, and the second one reveals the appearance of the protein Amide I band. Supplementary, AFM measurements clearly revealed the presence of collagen attached on the polymer surface. Thus, these new UV-irradiated polymers are promising materials in our further attempts to obtain new biofunctionalized surfaces.

Improvement of poly(ester-urethane) surface properties by RAFT mediated grafting initiated by gamma radiation

RAFT (ang. Reversible Addition–Fragmentation chain Transfer) polymerization has been considered as one of the most successful techniques for the preparation of polymers with predetermined molecular weights, narrow molecular weight distributions and high degree of chain end functionalities. This method was used for grafting of N-isopropylacrylamide onto polyurethane (PUR) surface to improve biocompability of the matrix surface. The pristine and grafted samples were investigated by the following surface characterization techniques: ATR-FTIR spectroscopy and scanning electron microscopy (SEM). The analysis of paramagnetic species was performed by EPR spectroscopy in order to evaluate the ability of PUR to form covalent bonds with monomer molecules. Grafting of PNIPAAm onto PUR surface in controlled manner was confirmed by GPC. The wettability of PUR and PUR-g-PNIPAAm surfaces was evaluated by contact angle (CA) measurements. Preliminary in vitro cytotoxicity experiments were carried out to study biocompability of pristine and modified samples using MTT assay. Attachment and proliferation of MG-63 osteosarcoma cells on polyurethane films before and after radiation grafting was investigated to assess the potential use of this material for biomedical applications.The applied modification resulted in surface changes of poly(ester-urethane). Polyurethane matrix coated by poly(N-isopropylacrylamide), the polymer classified to the group of thermosensitive polymers, exhibited hydrophilic properties in water at 25°C, while at 35°C the surface properties change into hydrophobic. Additionally, narrow molecular weight distribution of the grafted chains was obtained, uniformly covering the surface of the matrix. In vitro studies confirmed that the modified matrices are not cytotoxic when degree of NIPAAm grafting is 14% and number-average molecular weight of the grafted chains (Mn) is about 40,000g/mol.

Preparation and characterization of hydrophilic silicon dioxide film on acrylate polyurethane coatings with self-cleaning ability

A hydrophilic silicon dioxide film which was prepared by silicon dioxide sol could be coated on the acrylate polyurethane coating and translate the wettability of the coating from hydrophobic (CA=85°) to hydrophilic (CA=16°). The silicon dioxide sol was prepared by hydrolyzing tetraethoxysilane (TEOS) in aqueous medium and formed a hydrophilic film on acrylate polyurethane surface at 60°C. The concentration of silicon dioxide sol influenced the film wettability and the hydrophilicity was studied by static contact angle and sliding angle measurements. It was observed that with increase in the ratio of the water/silicon dioxide sol from 0:1 to 3:1, the contact angle decreased from 35° to 16° and the sliding angle decreased obviously. Compared with hydrophobic acrylate polyurethane coating, the hydrophilic silicon dioxide film exhibited better self-cleaning ability which was confirmed by the self-cleaning test through measuring the specular gloss of coatings before contamination and after water droplets spray. Furthermore, there was little dust left on the hydrophilic silicon dioxide film after exposed to an outdoor environment for ca. 50 days.

Polyaniline-coated polyurethane foam for pressure sensor applications

In this article, conductive composite foams were developed by in situ polymerization of aniline on polyurethane (PU) foam. After the polyaniline (PANI) deposition process on the interior surfaces of the porous PU foams, the nonconductive PU foams became conductive composites. The morphology of coating has been observed by means of scanning electron microscopy (SEM). The PANI-coated foam has been characterized chemically by means of energy-dispersive X-ray (EDX) and spectrometric analyses. The thermal characterization has been carried out by means of differential scanning calorimetery (DSC). The developed PANI-coated foam was subjected to compression tests in Zwick/Roell tensile tester, and electrical resistance was recorded during the tests to study the pressure-sensing mechanism. The stability of the developed sensor was characterized with respect to temperature and humidity using programmable environmental test chamber. The SEM studies revealed the deposition of PANI onto the PU surface, and the presence of sulfur content in PANI-coated foam was found through EDX analysis. The treated foam showed increase in light absorption during spectrometric analysis. From DSC studies, it was found that there is reduction in the melting temperature of PU foam after PANI coating. The conductive foam exhibited varying electrical properties with respect to compression. It was found that a linear relationship existed between change in electrical resistance and applied pressure up to 100 N/m2, and the changes are less beyond this, making it suitable for pressure sensor applications for 0–100 N/m2 pressure range.

Preparation and property of waterborne UV‐curable chain‐extended polyurethane surface sizing agent: Strengthening and waterproofing mechanism for cellulose fiber paper

ABSTRACTWaterborne UV‐curable polyurethane (UWPU) dispersions with different hydrophilicity and functionalities were prepared by varying the content of dimethylol butanoic acid (DMBA) and pentaerythritol triacrylate (PETA). And linear and cyclic chain extenders with different functionalities were also incorporated into the UWPU backbone, including isophorone diamine (IPDA), diethylene triamine (DETA), and ethylene diamine (EDA). Effects of DMBA content, PETA content, photoinitiator content, UV curing time, chain extender on the properties of UWPU dispersions and films, as well as the properties of the unsized and sized paper were investigated. The water resistance and mechanical properties of sized paper were greatly relied on the particle size, the molecular weight, the croslinking density, and penetrability of UWPU. UWPU dispersion chain extended with IPDA (IPDA‐UWPU) displayed smaller particle size than that of UWPU. The paper sized with IPDA‐UWPU was endowed with best water resistance, tensile strength, folding strength and surface strength. XPS depth analysis revealed that IPDA‐UWPU exhibited better penetrability into the paper substrate than UWPU. SEM and AFM demonstrated that the smoothness of sized paper was improved, and the bond strength between fibers was enhanced. The obtained UWPU could be directly used as an effective and fast drying surface sizing agent for cellulose fiber paper. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42354.

Establishing proper scanning conditions in atomic force microscopy on polyimide and polyurethane samples and their effect on 3D surface texture parameters.

Several atomic force microscopy (AFM) tests have been carried out on both smooth (polyimide) and rough (polyurethane) surfaces so that to obtain the best results; subsequently, the optimization of experiments performed is presented. A special emphasis has been put on the effect of tip geometry, image pre-processing procedure, scanning area, resolution, pixel size, and cantilever oscillation amplitude in tapping mode, as well as on the quality of the topographical images and 3D surface texture parameters. After viewing the scanning tip and finding out its sharpness, degradation, and contamination, a simultaneous calibration in X, Y, and Z directions, lateral calibration of SPM scanners and detection of lateral non-linearity, hysteresis, creep, and cross-coupling effects has been made. We have established the following experimental parameters: proper scanning resolution (512 × 512 pixels), adequate pixel size (between 2.9 and 19.5 nm) and suitable intermittent contact region (moderate tapping) for which the AFM images present good contrast and resolution. Using these parameters, the values of 3D texture parameters remain constant. These kinds of measurements are extremely important to conduct further AFM experiments on polyimide and polyurethane surfaces under optimal conditions, thus avoiding unwanted artifacts on the morphological images or unrealistic values for the 3D surface texture parameters that might occur.

Semiconducting polyurethane/polypyrrole/polyaniline for microorganism immobilization and wastewater treatment in anaerobic/aerobic sequential packed bed reactors

ABSTRACTThe development of new materials for microorganism immobilization is very important in wastewater treatment. In this work polyurethane (PU) foams were modified polymerizing pyrrole and aniline onto their surface by chemical oxidization to obtain polyurethane/polypyrrole (PU/PPy), polyurethane/polyaniline (PU/PANI), and PU/(PPy‐co‐PANI) supports which were used to immobilize microorganisms for municipal wastewater treatment in batch mode and continuous flow using two sequential (anaerobic/aerobic) packed bed reactors (PBR) varying the total hydraulic retention time (HRT). The supports were characterized by Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) and tested in chemical oxygen demand (COD) removal during treatment of a municipal wastewater. It was observed from SEM analysis that globular nanostructures of PPy and PPy‐co‐PANI were formed onto the PU surface with average diameters between 100 and 300 nm, which are typical of aqueous polymerization of pyrrole monomer; however irregular nanostructures were observed when PANI was homopolymerized onto the PU foam. Batch wastewater treatment after 14 days showed COD removal efficiencies of 77%, 69%, 78%, and 80% for PU foam, PU/PPy, PU/PANI, and PU/(PPy‐co‐PANI), respectively; which was explained as a function of polymers morphology deposited onto the PU foam surface. Also it was observed from the sequential PBR that for 24 h and 36 h of HRT, 80 and 90% of COD removal can be achieved; respectively.© 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42242.

Surface biocompatible construction of polyurethane by heparinization

A macromolecular biocompatible surface modifier for polyurethane (PU), namely, polyurethane-block-poly (chloromethyl styrene) (PU-b-PCMS) copolymer, was synthesized by coupling hydroxyl-terminated PCMS with diisocyanate-terminated PU and further quaternizing. The synthesized surface modifier was blended with PU and heparin was absorbed on PU surface by ion exchange. The modification effectively increased the hydrophilicity and water absorption of PU. To evaluate the hemocompatibility of the modified blend films, the extent of platelet adsorption, plasma recalcification time and hemolysis were measured. To determine if the blend films were toxic to mammalian cells, viability of the cells cultured on the blend films was assayed. All results indicated that the blood and cell compatibilities of the PU films were improved significantly after entrapment of a few quaternized PU-b-PCMS copolymers into PU and further heparinizing.

Designing of dynamic polyethyleneimine (PEI) brushes on polyurethane (PU) ureteral stents to prevent infections

Permanent antibacterial coatings have been developed by brush-like polyethyleneimine (PEI) on polyurethane (PU) ureteral stents since bacterial adhesion and biofilm formation with the following encrustation on stent surface limit their long term usage. In order to control or prevent bacterial infections; PEI chains with two different molecular weights (Mn: 1800 or 60,000Da) were covalently attached on the polyurethane (PU) surface by “grafting to” approach to obtain a brush-like structure. Then, PEI brushes were alkylated with bromohexane to enhance the disruption of bacterial membranes with increasing polycationic character. X-ray Photoelectron and Infrared Spectroscopy investigations confirmed that PEI grafting and alkylation steps were performed successfully. Surface roughness in dry state increased dramatically from 65.8nm to 277.7nm and 145.2nm for short chain PEI and long chain PEI grafted samples, respectively. Both low and high molecular weight PEI grafts exhibited a brush-like structure and potent antibacterial activity by lowering the adherence of Klebsiella pneumonia, Escherichia coli and Proteus mirabilis species up to two orders of magnitude without any cytotoxic effect on L929 and G/G cells. Thus, permanent bactericidal activity was achieved by the contact-active strategy of dynamic PEI brush-like structures on polyurethane ureteral stent.

Introduction of an Enhanced Binding of Reduced Graphene Oxide to Polyurethane Sponge for Oil Absorption

Reduced graphene oxide (rGO) was covalently bound onto the surface of polyurethane (PU) sponge using two different coupling agents: (3-aminopropyl)triethoxysilane and titanium(IV)(triethanolaminato)isopropoxide. The coupling agents were introduced before and after reduction of graphene oxide to compare the impact of the sequence on the absorbance capacities. The sponges were evaluated based on hydrophobicity and pump oil absorbance capacities. The structure and properties of the sponges were evaluated using scanning electron microscopy and Fourier transform infrared spectroscopy. Results revealed that reacting the graphene oxide PU sponge with the coupling agent titanium(IV)(triethanolaminato)isopropoxide prior to reduction significantly improved oil absorbance. This was due to the improved binding of reduced graphene oxide to the polyurethane framework. The resulting improved rGO-coated PU sponge is a highly efficient and reusable sorbent material and is a promising alternative for oil–water separation applications.

Coating Polyurethane Surfaces by Electrostatic Charging Followed by Dip Coating/Electrophoretic Deposition

AimSurface associated infections are one of the main causes for failures associated with medical devices. Bacterial localization and biofilm formation may lead to acute and chronic infection. Biofilm on the surface protects the bacteria from the immune system and antibiotic therapy. This needs aggressive treatment of antibiotics. The high doses of antibiotic treatment prevent healthy tissue formation at the site and triggers antibiotic resistance. Thus, to prevent infections, various strategies have been developed besides conventional systemic and local antibiotic treatment. Recently, there is an increasing interest for coating these surfaces to improve bioactivity and prevent infection. The current study aimed to modify the surface of polyurethane endotracheal tubes by charging them electrostatic ally to induce a positive and then coating them with an anti‐ bacterial protein via dip coating(3 times for a minute each) and electrophoretic deposition(using titanium foil as counter and working electrode at a voltage of 20V for 10 minutes).Results and conclusionimage(a)image(b)
Figure 1: SEM images of the coated surfacesA thick and uniform coating was achieved on both the inside and outside surfaces of the tubes. Bioactivity of the protein was maintained and the entire process was cost and time efficient.AcknowledgementsThe authors would like to thank N8 Medical devices and Northeastern university for funding and Brigham Young University for providing the endotracheal tubes.

Effect of plasma treatment on the hydrophobicity of imitation leather with 100% polyurethane surface

This paper examines the effect of atmospheric pressure plasma (APP) treatment on surface hydrophobicity of imitation leather with 100 % polyurethane surface with organosilane precursor. Based on the APP treatment with precursor, a single-step surface process on imitation leather was achieved. The results showed that under a particular combination of treatment parameters, a hydrophobic surface is achieved on the APP treated sample. Other than water, coffee, milk, and tea were also used for evaluating the surface hydrophobicity of plasma treated imitation leather and both liquids achieved higher contact angle when compared with the untreated sample.

An engineered micropattern to reduce bacterial colonization, platelet adhesion and fibrin sheath formation for improved biocompatibility of central venous catheters.

BackgroundCatheter-related bloodstream infections (CRBSIs) and catheter-related thrombosis (CRT) are common complications of central venous catheters (CVC), which are used to monitor patient health and deliver medications. CVCs are subject to protein adsorption and platelet adhesion as well as colonization by the natural skin flora (i.e. Staphylococcus aureus and Staphylococcus epidermidis). Antimicrobial and antithrombotic drugs can prevent infections and thrombosis-related complications, but have associated resistance and safety risks. Surface topographies have shown promise in limiting platelet and bacterial adhesion, so it was hypothesized that an engineered Sharklet micropattern, inspired by shark-skin, may provide a combined approach as it has wide reaching anti-fouling capabilities. To assess the feasibility for this micropattern to improve CVC-related healthcare outcomes, bacterial colonization and platelet interactions were analyzed in vitro on a material common for vascular access devices.MethodsTo evaluate bacterial inhibition after simulated vascular exposure, micropatterned thermoplastic polyurethane surfaces were preconditioned with blood proteins in vitro then subjected to a bacterial challenge for 1 and 18 h. Platelet adhesion was assessed with fluorescent microscopy after incubation of the surfaces with platelet-rich plasma (PRP) supplemented with calcium. Platelet activation was further assessed by monitoring fibrin formation with fluorescent microscopy after exposure of the surfaces to platelet-rich plasma (PRP) supplemented with calcium in a flow-cell. Results are reported as percent reductions and significance is based on t-tests and ANOVA models of log reductions. All experiments were replicated at least three times.ResultsBlood and serum conditioned micropatterned surfaces reduced 18 h S. aureus and S. epidermidis colonization by 70% (p ≤ 0.05) and 71% (p < 0.01), respectively, when compared to preconditioned unpatterned controls. Additionally, platelet adhesion and fibrin sheath formation were reduced by 86% and 80% (p < 0.05), respectively, on the micropattern, when compared to controls.ConclusionsThe Sharklet micropattern, in a CVC-relevant thermoplastic polyurethane, significantly reduced bacterial colonization and relevant platelet interactions after simulated vascular exposure. These results suggest that the incorporation of the Sharklet micropattern on the surface of a CVC may inhibit the initial events that lead to CRBSI and CRT.

Platelet adhesion, aggregation, and embolism on artificial surfaces in non-parallel blood flow

When using artificial surfaces that come into contact with the bloodstream, it is important to consider the undesirable consequences of thrombus formation and embolization. Although great progress has been made by creating new surfaces and antithrombotic coatings or evaluating flow conditions, unexpected platelet adhesion and aggregation can lead to the sudden formation of an adverse thrombus. Our experiments in a stagnation point flow chamber with citrate-anticoagulated whole blood and ADP-stimulated platelets mimicked the situations of implanted artificial organs, e.g., mechanical circulatory support devices, or extravascular circulation. With video microscopy, real-time platelet characteristics were observed at shear rate levels between 50 and 500 s−1 on glass, von Willebrand factor, and polyurethane surfaces for at least 5 min after the first contact. Platelet adhesion and aggregation were observed with distinctness in aggregate size, surface coverage, aggregate size, probability of an embolic event, and platelet contraction. The probability of an embolic event increased at lower flow rates. Additionally, platelet contraction was affected by the flow rate. Raising the flow rate intensified the platelet contraction. With this setup, the microembolization caused by surface contact and flow and platelet contraction can be detected in a real-time direct observation. This capability addresses both technical and clinical issues, such as thrombus and embolus formation, and may improve the research on the hemocompatibility of biomaterials.

Acyclic N-halamine-immobilized polyurethane: Preparation and antimicrobial and biofilm-controlling functions.

Hydroxyl groups were introduced onto polyurethane surfaces through 1,6-hexamethylene diisocyanate activation, followed by diethanolamine hydroxylation. Polymethacrylamide was covalently attached to the hydroxylated polyurethane through surface grafting polymerization of methacrylamide using cerium (IV) ammonium nitrate as an initiator. After bleach treatment, the amide groups of the covalently bound polymethacrylamide chains were transformed into N-halamines. The new N-halamine-immobilized polyurethane provided a total sacrifice of 107-108 colony forming units per milliliter of Staphylococcus aureus (Gram-positive bacteria), Escherichia coli (Gram-negative bacteria), and Candida albicans (fungi) within 10 min and successfully prevented bacterial and fungal biofilm formation. The antimicrobial and biofilm-controlling effects were both durable and rechargeable, pointing to great potentials of the new acyclic N-halamine-immobilized polyurethane for a broad range of related applications.