Surface Modification Of Polyurethane Research Articles

A Novel Approach to Water Softening Based on Graphene Oxide-Activated Open Cell Foams

This work focuses on exploring a new configuration for the reduction of water hardness based on the surface modification of polyurethane (PU) open cell foams by the deposition of thin graphene oxide (GO) washcoat layers. GO was deposited by the dip–squeeze coating procedure and consolidated by thermal treatment. The final washcoat load was controlled by performing consecutive depositions, after three of which, a GO inventory up to 27 wt% was obtained onto PU foams of 60 pores per inch (PPI). The GO-coated PU foams were assembled into a filter, and the performance of the system was tested by continuously feeding water with hardness in the 190–270 mgCa2+,eq·L−1 range. Remarkable results were demonstrated in terms of total adsorbing capacity, which was evaluated by measuring the outlet total hardness by titration and exhibited values up to 63 mgCa2+,eq·gGO−1 at a specific filtered water volume of 650 mLH2O·gGO−1, outperforming the actual state-of-the-art adsorbing capacity of similar GO-based materials.

Surface modification of polyurethane with eptifibatide-loaded degradable nanoparticles reducing risk of blood coagulation

The main purpose of the work was to develop a drug releasing coatings on the surface of medical devices exposed to blood flow, what should enable effective inhibition of blood coagulation process. As a part of the work, the process of encapsulating the anticoagulant drug eptifibatide (EPT) in poly(DL-lactic-co-glycolic acid) (PLGA) nanoparticles was developed. EPT encapsulation efficiency was 29.1 ± 2.1%, while the EPT loading percentage in the nanoparticles was 4.2 ± 0.3%. The PLGA nanoparticles were suspended in a polyanion solution (hyaluronic acid (HA)) and deposited on the surface-treated thermoplastic polyurethane (TPU) by a layer-by-layer method. As a polycation poly-L-lysine (PLL) was used. The influence of released EPT on the activation of the coagulation system was analyzed using dynamic blood tester. Performed experiments show an effective delivery of the drug to the bloodstream and low risk of platelets (membrane receptor) activation. The dynamic blood test process, including its physical phenomenon, was described using numerical methods, i.e. a finite volume cone-and-plate test model as well as non-Newtonian blood models. The values of shear stress and blood flow velocity under the fast-rotating cone were computed applying boundary conditions of cylinder wall imitating blood-nanomaterial interaction. Implementing boundary conditions as initial shear stress values of bottom cylinder wall resulted in the increase of shear stress in blood under rotating cone. The developed system combining drug eluting polymeric nanoparticles with the polyelectrolyte “layer-by-layer” coating can be easily introduced to medical implants of various shape, with the advantages of resorbable drug carriers allowing for local and controllable delivery of anti-thrombogenic drugs.

Grafting of niclosamide and salicylanilide onto hydrophilic polyurethane for the control of fungal and barnacle growth

Grafting of niclosamide or salicylanilide onto polyurethane (PU) was executed to develop antifungal effectiveness and barnacle repelling capability in seawater compared with underivatized PU. The PU surface was simultaneously modified to improve the surface hydrophilicity by inserting dimethylolpropionic acid into PU frame or by grafting recycled polyols onto PU. Surface modifications of PU significantly affected its properties, such as cross-link density, tensile and shape memory properties, and flexibility under freezing conditions relative to the unmodified PU. The modification of PU surface also notably influenced the glass transition and the melting and crystallization related to soft segments. The breaking tensile stress and the shape recovery were enhanced significantly after the grafting of polyol due to chemical cross-linking, whereas the breaking tensile strain was not reduced. Some PU samples demonstrated complete antifungal effectiveness against a mixture of fungi, and barnacle growth on PU films was limited in the specifically modified PUs.

Surface modification of polyurethane with a hydrophilic, antibacterial polymer for improved antifouling and antibacterial function.

Antimicrobial surface is important for the inhibition of bacteria or biofilm formation on biomaterials. The objective of this study was to immobilize a novel hydrophilic polymer containing the antibacterial moiety onto polyurethane surface via a simple surface coating technology to make the surface not only antibacterial but also antifouling. The compound 3,4-dichloro-5-hydroxy-2(5H)-furanone was derivatized, characterized and incorporated onto polyvinylpyrrolidone containing succinimidyl functional groups, followed by coating onto the polyurethane surface. Contact angle, antibacterial function and protein adsorption of the modified surface were evaluated. The result shows that the modified surface exhibited significantly enhanced hydrophilicity with a 54-65% decrease in contact angle, increased antibacterial activity to Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa with a 24-57% decrease in viability, and reduced human serum albumin adsorption with a 64-70% decrease in adsorption, as compared to the original polyurethane.

Surface modification of polyurethane via creating a biocompatible superhydrophilic nanostructured layer: role of surface chemistry and structure

ABSTRACTAdvanced surface modification approaches of biomaterials alongside the advent of sophisticated analytical techniques have provided a great opportunity to understand how the physicochemical characteristics of materials determine cell–surface dynamics at molecular and atomic scale. However, there are still many contradictory reports, which are mainly due to inadequate information about the role of the two parameters of surface chemistry and structure and their synergistic effect as an adequate predictor of biological performance. Here, surface parameters were altered by grafting of poly ethylene glycol (PEG) on polyurethane (PU) surfaces through a superhydrophilic modification method. In this study, surface modification of PU films by PEG thin layer via grafting technique and TiO2 nanoparticle entrapment in the brush polymers was investigated. The surface modification led to a reduction in protein adsorption and bacterial attachment by 8.7 times and 71% respectively with no cytotoxicity effect on HeLa cells. It was also observed that when PU surface became superhydrophilic the bacterial adhesion becomes independent of bacterium type. In general, it was observed that the impact of topographical changes on the biocompatibility and biofilm formation becomes significantly more profound than that of the surface chemistry alteration.

Biomimetic surface modification of polyurethane with phospholipids grafted carbon nanotubes.

To improve blood compatibility of polyurethane (PU), phospholipids grafted carbon nanotubes (CNTs) were prepared through zwitterion-mediated cycloaddition reaction and amide condensation, and then were added to the PU as fillers via solution mixing to form biomimetic surface. The properties of phospholipids grafted CNTs (CNT-PC) were investigated by thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and proton nuclear magnetic resonance ((1) H NMR). The results indicated that the phospholipids were grafted onto CNTs in high efficiency, and the hydrophilicity and dispersibility of the modified CNTs were improved effectively. The structures and properties of composites containing CNT-PC were investigated by optical microscope, XPS, and water contact angles. The results indicated that phospholipids were enriched on the surface with addition of 0.1 wt % of CNT-PC, which significantly reduced protein adsorption and platelet adhesion. The method of carrying phospholipids on the nanofiller to modify polymers has provided a promising way of constructing biomimetic phospholipid membrane on the surface to improve blood compatibility.

Surface modification of polyurethane via covalent immobilization of sugar-based trisiloxane surfactants

Sugar-based trisiloxane surfactants (N-siloxanegluconamides and N-siloxanelactobionamides, denoted as Si(3)NGA and Si(3)NLA) with the amphiphilic structures were successfully prepared. Polyurethane (PU) was grafted with 2-carboxyethyl acrylate (CEA) by the means of UV-induced graft polymerization, and further introduction of the Si(3)NGA and Si(3)NLA by conjugating the amino groups and acid groups. The surface graft polymerization was confirmed by attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. Water contact angle, protein adsorption, and platelet adhesion measurements were used to evaluate the hydrophilicity and hemocompatibility of the films. It was found that the Si(3)NGA-modified substrates obviously suppressed protein adsorption and platelet adhesion, while Si(3)NLA-modified substrates exhibited a higher protein adsorption and a coagulating performance of blood.

Synthesis and surface modification of polyurethanes with chitosan for antibacterial properties

Surface modification and providing antibacterial properties to the materials or devices are getting great attention especially in the last decades. In this study, polyurethane (PU) films were prepared by synthesizing them in medical purity from toluene diisocyanate and polypropylene ethylene glycol without using any other ingredients and then the film surfaces were modified by covalent immobilization of chitosan (CH) which has antibacterial activity. CH immobilized PU films (PU-CH) were found to be more hydrophilic than control PU films. Electron Spectroscopy for Chemical Analysis (ESCA) and Atomic Force Microscopy (AFM) analyses showed higher nitrogen contents and rougher surface topography for PU-CH compared to PU films. Modification with CH significantly increased antibacterial activity against Gram positive (Staphylococcus aureus) and Gram negative (Pseudomonas aeruginosa) bacteria. It was observed that the number of bacteria colonies were less about 102–105CFU/mL and number of attached viable bacteria decreased significantly after CH modification of PU films.

Surface modification of polyurethane towards promoting the ex vivo cytocompatibility and in vivo biocompatibility for hypopharyngeal tissue engineering

Polymeric substrates with good biocompatibility have been widely employed to create a living construct with the complexities of tissue histology and function in the field of tissue engineering. In this study, poly(ester-urethane) (58213, NAT022) was used to be substrate due to its good physical and chemical properties. Proteins like gelatin or silk fibroin were covalently bonded on its surface using method of diamine aminolysis and glutaraldehyde crosslinking, which had been setup in our group in order to improve poly(ester-urethane)'s hydrophilicity and biocompatibility. The modification was proved by the measurements of static and dynamic contact angles and fluorescence detection. The biological properties were evaluated as in vitro cell culture and in vivo transplantation via cell number counting, morphology observation, immunohistochemistry analysis, etc. The results showed that gelatin or silk fibroin grafted membrane displayed good cytocompatibility, i.e. good proliferation and differentiation of human hypopharynx fibroblast and skeletal muscle cell though the control poly(ester-urethane) indicated low toxicity to cells and good biocompatibility, which was also verified in in vivo experiment. After poly(ester-urethane)-silk fibroin was implanted subcutaneously in rat back, it exhibited a better compatibility to peripheral tissue and faster biodegradation than the control poly(ester-urethane) did. This information supplied us valuable knowledge for poly(ester-urethane) to be used as matrix in situ hypopharynx regeneration study.

Surface modification of polyurethane with acrylamide by plasma radiation and its cellular investigations

Surface modification of polyurethane with acrylamide by plasma radiation and its cellular investigations

Modification of Polyurethane Surface with an Antithrombin–Heparin Complex for Blood Contact: Influence of Molecular Weight of Polyethylene Oxide Used as a Linker/Spacer

Polyurethane (PU) was modified using isocyanate chemistry to graft polyethylene oxide (PEO) of various molecular weights (range 300-4600). An antithrombin-heparin (ATH) covalent complex was subsequently attached to the free PEO chain ends, which had been functionalized with N-hydroxysuccinimide (NHS) groups. Surfaces were characterized by water contact angle and X-ray photoelectron spectroscopy (XPS) to confirm the modifications. Adsorption of fibrinogen from buffer was found to decrease by ~80% for the PEO-modified surfaces compared to the unmodified PU. The surfaces with ATH attached to the distal chain end of the grafted PEO were equally protein resistant, and when the data were normalized to the ATH surface density, PEO in the lower MW range showed greater protein resistance. Western blots of proteins eluted from the surfaces after plasma contact confirmed these trends. The uptake of ATH on the PEO-modified surfaces was greatest for the PEO of lower MW (300 and 600), and antithrombin binding from plasma (an indicator of heparin anticoagulant activity) was highest for these same surfaces. The PEO-ATH- and PEO-modified surfaces also showed low platelet adhesion from flowing whole blood. It is concluded that for the PEO-ATH surfaces, PEO in the low MW range, specifically MW 600, may be optimal for achieving an appropriate balance between resistance to nonspecific protein adsorption and the ability to take up ATH and bind antithrombin in subsequent blood contact.

Surface modification of polyurethane and silicone for therapeutic medical technics by means of electron beam

Surface modification technologies are gaining growing acceptance for treatment of implant materials to enhance biocompatibility. Our examinations focus on polyetherurethane and silicones, two typical flexible implant materials, which we have modified by non-thermal electron beam processing. Advantages of this method are the adjustable degree of modification as well as the simultaneous sterilizing effects. The polymer surfaces were characterized with regard to wetting behavior, surface energy, chemistry and morphology. The cell adhesion was examined too. The results reveal that the electron beam is a useful tool for surface modification of polymers.

IMPROVING ADHESION OF SILICONE RUBBER COATING TO POLYURETHANE SURFACE

Surface modification of polyurethane(PU) by appropriate treatment and introducing silane coupling agent to PU surface was used to improve the adhesion of PU to silicone rubber(SR).FTIR and X-ray energy spectrometer were employed to investigate the surface treatment and graft reaction of silane coupling agent,while surface morphology and properties of materials were characterized by scanning electron microscopy and water contact angle.Different PU/SR interfaces after oscillation and shear were compared as well.The results indicated that the hydrophilicity of PU was improved after surface treatment,which generated more hydroxyl groups that could react with isocyanate-terminated silane coupling agent.When condensed room temperature vulcanized SR was poured onto PU surface,the silane coupling agent on PU surface could condense with it to improve the adhesion of PU and SR by connecting them with chemical bonds.

Surface Modification of Polyurethanes with Covalent Immobilization of Heparin

AbstractThrombus formation and blood coagulation is a major problem associated with blood contacting products such as catheters, vascular grafts, arteries, artificial hearts and heart valves. An intense research is being conducted towards the synthesis of new hemocompatible materials and modifications of surfaces with biological molecules. In this study, polyurethane (PU) films were synthesized in medical purity from diisocyanate and polyol without using any other ingredients and their surfaces were modified by covalent immobilization of heparin. Two types of heparin, unfractionated (UFH) and low molecular weight heparin (LMWH), were immobilized to investigate their effect on cell adhesion. The surface properties of the modified PUs were examined with ESCA, ATR‐FTIR and AFM. ESCA results demonstrated sulfur peaks indicating the presence of heparin and AFM results showed the alteration of surface structure after coating with heparin. Cell adhesion studies were conducted with heparinized whole human blood. The surfaces of the UFH immobilized films resulted in lesser red blood cell adhesion in comparison to LMWH demonstrating strong anti‐thrombogenic activity of the latter.

Surface modification of polyurethane using sulfonated PEG crafted polyrotaxane for improved biocompatibility

Sulfonated poly(ethylene glycol) (PEG-SO3) grafted polyrotaxanes (PRx-PEG-SO3) were prepared in order to utilize the unique properties of PEG-SO3 and the supramolecular structure of PRx, in which PEG-SO3 grafted α-cyclodextrins (α-CDs) were threaded onto PEG segments in a PEG-b-poly(propylene glycol) (PPG)-b-PEG triblock copolymer (Pluronic) chain capped with bulky end groups. Some of the PRx-PEG-SO3 demonstrated a higher anticoagulant activity in case of PRx-PEG-SO3 (P105), and compared with the control they showed a lower fibrinogen adsorption in PRx-PEG-SO3 (F68) and a higher binding affinity with fibroblast growth factor. The obtained results suggested that polyrotaxane incorporated with PEG-SO3 may be applicable to the surface modification of clinically used polymers, especially for blood/cell compatible medical devices.

Properties of phospholipid monolayer deposited on a fluorinated polyurethane

A simple procedure for surface modification of polyurethane by the Langmuir–Blodgett (LB) method using the amphiphile 1,2-distearoyl-sn-glycero-3-phosphocholine dihydrate (DSPC) was developed. The polyurethane containing the fluorinated moiety was prepared via the perfluorocontaining chain extender 2,2,3,3-tetrafluoro-1,4-butanediol. The fluorinated polyurethane (FPU) films were prepared by spin coating and dipping methods. The spin-coated FPU films exhibited hydrophobic characteristic and, thus, enhanced the transferability of DSPC. Held at constant pressure of 45 mN/m, the DSPC monolayer was transferred successfully to FPU films with a near-unity transfer ratio. The in vitro platelet adhesion assay revealed that the FPU modified with DSPC monolayer was more platelet compatible than the unmodified FPU substrates with no pseudopods and flattening of adherent platelets as well as lower platelet adhesion density. Moreover, the DSPC monolayer remained intact after platelet adhesion testing. In addition, the platelet compatibility of the unmodified FPU was affected by the film preparation methods. This might be attributed to the distinctive surface micromorphology formed. This simple DSPC deposition scheme by a LB technique would be very useful to further enhance the platelet compatibility of hydrophobic substrate and can be utilized for biomedical application in which the flow shear rate is not too high.

Polyurethane surfaces modified by amphiphilic polymers: effects on protein adsorption

Surface modification of polyurethane (PUR) surfaces was carried out by using three different amphiphilic polymers. Two of the polymers were graft copolymers, having backbones consisting of poly(methyl methacrylate-co-ethylhexyl acrylate) and poly(styrene-co-acrylamide), respectively, and poly(ethylene oxide) PEO 2000 grafts. The third polymer was a commercially available poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer, Pluronic 9400. The polymers were designated ACRY, STY2, and PE94, respectively. Surface modification was achieved by adsorption of the amphiphilic polymers at PUR surfaces from an aqueous solution, or by blending the amphiphiles into a PUR solution, followed by solution casting of films. The accumulation of the amphiphilic polymers at the PUR surfaces was observed by XPS and contact angle measurements. The ACRY and PE94 polymers were shown to adsorb poorly at the PUR surface, but gave strong surface effects when present in the PUR matrix. Protein adsorption was measured under static as well as under flow conditions. The modified surfaces had generally lower adsorption of blood proteins (HSA, Fg and IgG) than the unmodified PUR surfaces. ACRY blend modified surfaces had the lowest adsorption.

Surface modification of polyurethanes by multicomponent polyaddition reaction

Surface modification of polyurethanes by multicomponent polyaddition reaction

Surface modification of polyurethane by plasma‐induced graft polymerization of poly(ethylene glycol) methacrylate

A new approach, plasma-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA), was used to introduce PEG graft chains with hydroxyl end groups onto a polyurethane (Tecoflex) surface. After argon plasma treatment and subsequent exposure to air, graft polymerization onto Tecoflex films was allowed to proceed in deaerated aqueous solutions of PEGMA at 60°C. The virgin, plasma-treated, and grafted films were characterized comparatively by means of attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, measurement of contact angle, and protein adsorption. The Tecoflex film undergoes etching during argon plasma treatment, surface oxidation when exposed to air after plasma treatment, and surface restructuring in response to environment upon storage in air. The plasma-induced graft polymerization of PEGMA proved to be successful in introducing PEG graft chains with reactive hydroxyl end groups onto the surface. Grafted films with different surface grafting density of PEG were prepared. Grafted films with higher PEG content exhibit higher hydrophilicity, smoother topography, and lower fibrinogen adsorption. The hydroxyl end groups built onto the surface offer further possibilities of improving its biocompatibility by immobilizing bioactive molecules.

Surface modification of polyurethane by plasma-induced graft polymerization of poly(ethylene glycol) methacrylate

A new approach, plasma-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA), was used to introduce PEG graft chains with hydroxyl end groups onto a polyurethane (Tecoflex) surface. After argon plasma treatment and subsequent exposure to air, graft polymerization onto Tecoflex films was allowed to proceed in deaerated aqueous solutions of PEGMA at 60°C. The virgin, plasma-treated, and grafted films were characterized comparatively by means of attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, measurement of contact angle, and protein adsorption. The Tecoflex film undergoes etching during argon plasma treatment, surface oxidation when exposed to air after plasma treatment, and surface restructuring in response to environment upon storage in air. The plasma-induced graft polymerization of PEGMA proved to be successful in introducing PEG graft chains with reactive hydroxyl end groups onto the surface. Grafted films with different surface grafting density of PEG were prepared. Grafted films with higher PEG content exhibit higher hydrophilicity, smoother topography, and lower fibrinogen adsorption. The hydroxyl end groups built onto the surface offer further possibilities of improving its biocompatibility by immobilizing bioactive molecules. © 1996 John Wiley & Sons, Inc.