Effects of thermal annealing of segmented-polyurethane on surface properties, structure and antithrombogenicity

Analyses of the surface structure and properties of thermally heat-treated and non-treated segmented-polyurethane (SPU) surfaces showed that a crystalline structure, the domain size of which was larger than that of the micro-phase separation structure, appeared when the SPU surface was annealed in the temperature range of 60–140 °C. The appearance of the crystalline structure resulted in a decrease in surface free energy, that is, an increase in the hydrophobicity of the surface. Whole blood or platelet-rich plasma (PRP), when in contact with a SPU surface, which had previously been in contact with a glass surface during casting, coagulation of the whole blood occurred within approximately 30 min and, in case of PRP, in approximately 60 min. When the SPU surface was modified by thermal annealing, the coagulation time for PRP was delayed, whereas that of whole blood remained essentially unchanged. Relationships between the surface properties and the structure of annealed SPU and antithrombogenicity are discussed. The data collected herein suggest that the heat treatment of SPU might be useful for improving antithrombogenicity.     

磷酰胆碱共聚物(MPC-co-EHMA)的合成及对聚氨酯膜的生物相容性影响

2-甲基丙烯酰氧乙基磷酰胆碱(MPC)与甲基丙烯酸异辛酯(EHMA)通过自由基聚合制备共聚物PMEH20,并将PMEH20添加到基材聚氨酯中制备了共混膜。牛血清蛋白(BSA)吸附性测试显示当PMEH20质量分数为15%时,BSA吸附量比空白聚氨酯下降了81.7%;血小板粘附性能测试显示,含有PMEH20的聚氨酯共混膜粘附了更少的血小板;动态水接触角测试发现共混膜中磷酰胆碱基团可以通过翻转重排于薄膜表面;薄膜力学性能测试显示,在PMEH20质量分数达到10%时,膜材料的综合力学性能最好。     

Enhancement of the ionic conductivity of poly(ethylene oxide) electrolyte film by polyaniline addition

To improve the electrical conductivity of LiClO₄–poly(ethylene oxide) (PEO) complex, nonconductive polyaniline (NPANI) was employed as an additive. The electrical conductivity of the PEO–LiClO₄–NPANI electrolyte was at least ten times that of the original PEO–LiClO₄ electrolyte. The amine and/or imine nitrogen atoms in the NPANI polymer chain as well as the oxygen atoms in the PEO poly-merchain attracted the Li⁺ ions, and ion-dipole interaction occurred. The interaction enhanced the mobility of the ClO₄ ^– ions. The positively charged nitrogens were electronically stabilized in the entire polymer chain because NPANI had conjugated electrons. The mechanism is unique and different from those of other polymer additives. It is the very first example in which NPANI was employed as the additive for the PEO solid electrolyte and in which NPANI was found to be an effective additive. In addition, the NPANI addition hardly affected the physical properties of the PEO matrix such as the glass transition temperature and the melting temperature.     

Interface between zinc phosphate-deposited steel fibres and cement paste

In an attempt to protect steel fibre reinforcements from corrosion and improve their adherence to cement pastes, we deposited a zinc phosphate (ZnPh) conversion coating on the surface of the fibres. At the interfacial contact zones between the cement paste and ZnPh, alkali-induced dissolution caused the dissociation of abundant PO ₄ ^3– ions from the ZnPh. The interaction of PO ₄ ^3– ions with Ca²⁺ ions from the pastes led to the formation of hydroxyapatite and brushite in the vicinity of the dissolved ZnPh surface. Such intermediate calcium phosphate compounds played important roles in (1) improving the cement-fibre interfacial bonds, and (2) repairing the damage of the ZnPh surfaces dissolved by alkali. These processes protected the steel fibre from corrosion.     

Domain-controlled polymer alloy composed of segmented polyurethane and phospholipid polymer for biomedical applications

Segmented polyurethane(SPU)s are block polymers which have a good elastic property and thermoplasticity. However, the biocompatibility of SPU is not sufficient, and a living organism rejects the SPU as a foreign material. Thus, some modification is needed to provide excellent biocompatibility and retain the good physical characteristics of the SPUs. In this study, we blended the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer with SPU to prepare an SPU/MPC polymer alloy. We investigated the effects of the molecular weight (M_w) of the MPC polymer on the microdomain structure and mechanical property of the polymer alloy. When the MPC polymer with a higher M_w was blended with SPU, the polymer alloy underwent a reduction in mechanical strength. On the other hand, even when the lower M_w of the MPC polymer was blended with SPU, differential scanning calorimetric analysis revealed that the MPC polymer chains did not disrupt the crystallinity of the hard segments of SPU and the polymer alloy could maintain its physical properties the same as that of the original SPU. We investigated the adsorption of immunoglobulin (IgG) on the surface of the polymer alloy for evaluation of its fundamental biocompatibility. The SPU/MPC polymer alloy lowered the amount of adsorbed IgG compared to that on SPU. This means that the blending of the MPC polymer significantly improved the biocompatibility of the SPU. We succeeded in preparing an SPU/MPC polymer alloy that possesses both the good mechanical property of SPU and the improved biocompatibility using MPC polymers.     

Technique for testing aspherical surfaces

Conclusions The above technique was used for measuring and appropriately processing the results obtained for spherical (concave and convex), parabolic, elliptical, and hyperbolic surfaces (in the case of a spherical surface the measured distance d is the radius r).The obtained results were found to be so precise that they can be recommended for application in the technique for precise practical measurements of surface shapes. This method is based on comparison with surfaces of predetermined shape whose meridional cross section can be represented by an equation for a circle, parabola, and hyperbola.After the surface measurements the meridional cross-section curves were identified according to the method under consideration. Discrepancies in the determined parameters were discovered by comparing the parameters of surfaces with a given shape to the identified surfaces. Thus, the discrepancies for the different surfaces are: spherical — 1·10^–3, elliptical and hyperbolic — 2.10^–2, parabolic — 6·10^–3.Translated from Izmeritel'naya Tekhnika, No. 1, pp. 13–15, January, 1981.     

Effects of nanoclay and polyurethanes on inhibition of mild steel corrosion

Sulfonated polyurethanes (SPU) were used as corrosion inhibitor for mild steel in acidic solution. The sulfonation of the > N-H groups of the urethane linkages was confirmed from Nuclear Magnetic Resonance (NMR) and Fourier Transform Infra Red (FTIR) spectroscopic techniques. The inhibition efficiency of sulfonated polyurethanes, prepared from two different routes, was investigated using different techniques. The effects of microstructure of polyurethane (PU), degree of sulfonation, time of immersion and temperature on the inhibition of corrosion were discussed. The disc-like nanoparticles, so-called nanoclay, either suspended or chemically attached to SPU chains (nanocomposites) dramatically enhanced the inhibition efficiency for mild steel in acidic medium. All the inhibitors retard the corrosion rate by getting themselves adsorbed on the corroding surface by following the Langmuir adsorption isotherm. The surface analysis of inhibited and uninhibited samples was performed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Among the various inhibitors used, the nanocomposite of polyurethane was the most effective. Molecular modeling helped in determining the extent of packing of the SPU chains leading to better inhibition efficiency.     

Hydrogen bonding in poly(styrene-mono-ethyl-maleate)

This paper studies the styrene-(mono-ethyl-maleate) copolymer using IR spectroscopy. The copolymer was obtained by styrene copolymerization with maleic anhydride, in ethanol as the reaction medium. The IR spectra recorded give information concerning the physico-chemical structure, the monomer ratio and emphasize the intermolecular interactions corresponding to the hydrogen bond associations. The elevated temperature studies (90–130°C) allowed us to establish the equilibrium constants, the enthalphy and entropy variation, values of –4.2 kcal mol^-1 and –3.7 e.u. mol^-1, respectively, being obtained.     

FTIR spectral characterization of thin film coatings of oleic acid on glasses: I. Coatings on glasses from ethyl alcohol

Oleic acid was coated on soda lime–silicate, soda-silicate, and silica glasses from ethyl alcohol. The coating properties of oleic acid were related to the structure, composition, and dissolution properties of the glasses. The bonding mechanism between the organic coating and the glass surface for each different composition of the glass was revealed by analysis of the diffuse reflectance infrared Fourier transform (DRIFT) spectra. The metal ions on the soda lime–silicate glass surface produced metal-(Na-, Ca-, and Al-) oleates through the formation of metal–carboxylate complexes. Two different structural types were present for calcium-oleate. Some of the oleic acid coated undissociatively on the glass surface through hydrogen bonding. Oleic acid reacted with the surface of the soda-silicate glass, which possessed less Na2O content than the soda lime–silicate glass did, completely dissociating, producing only sodium-oleate species because of the high diffusion and dissolution rates of Na+ ions. Oleic acid formed only hydrogen bonds with silanol groups on silica glass. The coated organic layer on soda lime–silicate glass possessed a more ordered and compact structure than either on silica glass or in pure oleic acid. The metal ions on the soda lime–silicate glass surface strongly coordinated to COO– ions from the oleic acid and made the alkyl chains of the oleates more rigid and oriented, consequently causing the coated layer to be more ordered and compact. This structural result caused the dimeric pairs of COOH groups of undissociatively adsorbed oleic acid molecules to be closer, possessing stronger hydrogen bonds than occurring on the silica glass surface. These results suggest that the composition of the glass is one of the most important factors for determining the coating mechanism involving oleic acid.     

Effect of the surface treatment on the room-temperature bonding of Al to Si and SiO2

Bonding of polycrystalline Al to Si(1 0 0) and SiO2 (fused silica) was carried out at room temperature by means of surface-activated bonding method. In the present work, different means of surface activation such as irradiation of an argon fast atom beam (FAB) and a hydrogen radical beam (RB) were used. Influence of the exposure to a vacuum atmosphere of the activated surfaces by fast atom irradiation on the bonding behaviour was investigated. The strength of the Al–Si joints sputter cleaned by FAB before bonding reaches as much as 32 MPa. When the activated surfaces were exposed to 30 L (where L is the abbreviation for langmuir (1.33×10-4 Pa s)) in the residual gases (mainly vapour), the strength of the Al–Si joint decreased to 20 MPa and approached that of the Al–SiO2 joint. This indicates that the fracture strength of the joint of Al and Si with an intermediate layer of OH groups and oxide is close to that of Al and Si oxide. The adhesion between Al and Si deteriorated strongly because of hydrogen termination on the Si surface which had been irradiated by the hydrogen RB. On the contrary, bonding of Si with native oxides to Al was successful with the hydrogen RB irradiation.     

A study on compatibilization of AES/PA6 blends

Polyblends of Nylon 6 and AES were prepared and their mechanical properties and phase morphology examined. Two compatibilization techniques were evaluated: addition of a suitable block copolymer: poly(styrene-co-maleic anhydride) (SMA); AES functionalization with maleic anhydride (MA) through reactive extrusion. As a preliminary test for the compatibilizing efficiency, SMAs and PA6 were compounded in a Brabender mixer, recording the torque during the operations and evaluating, by solvent extraction, the amount of SMA grafted to PA6. However, when moving to the ternary blends AES/SMA/PA6, the highest value of notched lzod impact strength (290 J m^–1 versus 20 J m^–1) was found for an SMA sample containing 24% MA, which did not show the highest reactivity with PA6 in the preliminary test run. This finding suggests that not only the reactivity towards PA6, but also the miscibility with AES phase (the highest for the SMA product with 24% MA) must be taken into account when designing the best performing compatibilizer. On the other hand, AES functionalization with MA and DCP proved to be more successful and the resulting 50/50 blend with PA6 exhibited an outstanding value of notched Izod impact strength (1050 J m^–1)     

硅烷偶联剂改性聚氨酯的研究

从原料和工艺两方面出发,对以γ-氨丙基三乙氧基硅烷(KH550)为基础的硅烷改性聚氨酯(SPU)进行了改善.原料方面,改性后的KH550由伯氨基转化为仲氨基,反应活性降低;工艺方面,将KH550加料顺序提前.试验结果表明:这两种方法均有利于降低SPU树脂的黏度和提高反应平稳性;较好解决了由于黏度上升太快引起的KH550自聚凝团问题.     

Thermally Induced Losses in Ultra-Cold Atoms Magnetically Trapped Near Room-Temperature Surfaces

We have measured magnetic trap lifetimes of ultra-cold ⁸⁷Rb atoms at distances of 5–1000 µm from surfaces of conducting metals with varying resistivity. Good agreement is found with a theoretical model for losses arising from near-field magnetic thermal noise, confirming the complications associated with holding trapped atoms close to conducting surfaces. A dielectric surface (silicon) was found in contrast to be so benign that we are able to evaporatively cool atoms to a Bose–Einstein condensate by using the surface to selectively adsorb higher energy atoms.     

Bonding to aged surfaces: A thermally-aged epoxy

It is common experience that aged surfaces are often difficult to bond to. We report an examination of bonding to thermally-aged epoxy surfaces, using as the adhesive the same epoxy as that of the aged surface. The cured and postcured epoxy was aged at 200 ° C, with the ageing time varying from 2 to 8 h. The fracture energy of the bond line was measured by mode I cleavage under conditions of relatively slow crack growth. The bondline fracture energy was found to decrease logarithmically with ageing time. The fracture energies for bonds to surfaces aged for 2, 4, and 8 h at 200 ° C were 0.077, 0.059, and 0.050 kJ M^–2, respectively. These compare to 0.13 kJ M^–2 for a bond to an unaged surface and 0.21 kJ m^–2 for bulk fracture. Fracture surfaces resulting from both slow and rapid fracture were examined by optical and scanning electron microscopy. Fracture features different from those arising from bulk fracture were found. Areas with good adhesion occurred amidst fields of featureless fracture surface; the frequency and size of these areas decreased with increased ageing time. Evidence of plastic deformation was found, always occurring on the new side of the bond: ridges parallel with crack propagation at high crack speeds and subsurface undulations perpendicular to crack propagation at low speeds. The bond has the effect of channelling the crack along the bondline, but fracture does not always remain exactly at the interface. Fracture often occurred a relatively constant distance away from the interface, suggesting that the presence of the interface was felt for some distance.     

The effect of annealing temperature on the structure of diamond-like carbon films by electrodeposition technique

Diamond-like films have been prepared by electrodeposition in liquid phase. The films consist of a little amount of hydrogen, which can be removed by annealing at below 600 °C. The Raman signal of annealing films suggested: (1) the intensity ratio I_D/I_G increases which suggested that the crystallites grew in number and size with increasing temperature; (2) the D-line position changes from 1380 to 1346 cm^–1, and the G-line position from 1580 to 1604 cm^–1 which indicated that partially tetrahedral bonds have been broken and have transformed to trigonal bonds, (3) the linewidths of the D and G-line decrease with the increasing annealing temperature. These results indicated that the primary bonding in the films changed gradually from sp³-bonded to sp²-bonded carbon with increasing annealing temperature, i.e., graphitization.     

硅烷改性聚氨酯的合成

以氨基硅烷偶联剂为基础,对以异氰酸酯基为端基的聚氨酯预聚体进行再封端,合成了一系列不同硅烷封端率的单组分湿固化聚氨酯。测试结果表明:硅烷偶联剂成功接枝在聚氨酯预聚体上,产物的表干时间、粘接强度、耐湿热都得到很大改善,力学强度在一定封端率下保持较好,在聚氨酯密封胶、弹性体等领域有很好的应用前景。     

Domain-controlled polymer alloy composed of segmented polyurethane and phospholipid polymer for biomedical applications

Segmented polyurethane(SPU)s are block polymers which have a good elastic property and thermoplasticity. However, the biocompatibility of SPU is not sufficient, and a living organism rejects the SPU as a foreign material. Thus, some modification is needed to provide excellent biocompatibility and retain the good physical characteristics of the SPUs. In this study, we blended the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer with SPU to prepare an SPU/MPC polymer alloy. We investigated the effects of the molecular weight (M_w) of the MPC polymer on the microdomain structure and mechanical property of the polymer alloy. When the MPC polymer with a higher M_w was blended with SPU, the polymer alloy underwent a reduction in mechanical strength. On the other hand, even when the lower M_w of the MPC polymer was blended with SPU, differential scanning calorimetric analysis revealed that the MPC polymer chains did not disrupt the crystallinity of the hard segments of SPU and the polymer alloy could maintain its physical properties the same as that of the original SPU. We investigated the adsorption of immunoglobulin (IgG) on the surface of the polymer alloy for evaluation of its fundamental biocompatibility. The SPU/MPC polymer alloy lowered the amount of adsorbed IgG compared to that on SPU. This means that the blending of the MPC polymer significantly improved the biocompatibility of the SPU. We succeeded in preparing an SPU/MPC polymer alloy that possesses both the good mechanical property of SPU and the improved biocompatibility using MPC polymers.     

Characterization of trypsin immobilized on the functionable alkylthiolate self-assembled monolayers: A preliminary application for trypsin digestion chip on protein identification using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Self-assembled monolayers (SAMs) on coinage metal provide versatile modeling systems for studies of interfacial electron transfer, biological interactions, molecular recognition and other interfacial phenomena. Recently the bonding of enzyme to SAMs of alkanethiols onto Au electrode surfaces was exploited to produce a bio-sensing system. In this work, the attachment of trypsin to a SAMs surface of 11-mercaptoundecanoic acid was achieved using water soluble N-ethyl-N -(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide as coupling agent. The thickness of SAMs was determined by optical ellipsometer; contact angles of the modified Au surfaces were measured in air using a goniometer. The Second Harmony Generation data displays the last few percents of the alkylthiol molecules adsorbed and produced the complete monolayer by inducing the transition from a high number of gauche defects to an all-trans conformation. Using X-ray Photoelectron Spectroscopy (XPS) and Fourier-Transformed Infrared Reflection-Absorption and Attenuated Total Reflection Spectroscopes (FTIR-RAS and ATR), we examined the chemical structures of samples with different treatments. By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), we demonstrated the digestion of bovine serum albumin (BSA) on the trypsin-immobilized SAMs surface.Experimental results have revealed that the XPS C1s core levels at 286.3 and 286.5 eV (Amine bond), 288.1 eV (Amide bond) and 289.3 eV (Carboxylic acid) illustrate the immobilization of trypsin. These data were also in good agreement with FTIR-ATR spectra for the peaks valued at 1659.4 cm^{– 1} (Amide I) and 1546.6 cm^{– 1} (Amide II). Using MALDI-TOF MS observations, analytical results have demonstrated the BSA digestion of the immobilized trypsin on the functionalized SAMs surface. For such surfaces, BSA was digested on the trypsin-immobilized SAMs surface, which shows the enzyme digestion ability of the immobilized trypsin. The terminal groups of the SAMs structure can be further functionalized with biomolecules or antibodies to develop surface-base diagnostics, biosensors, or biomaterials.     

FT-IR ATR spectroscopy of the edge surface of pyrolytic graphite and its surface/PVC interface

The edge surface of pyrolytic graphite (PG) has been oxidized by electrochemical and oxygen plasma treatments. The structure of the oxidized edge surfaces of PG and the interaction between the oxidized surface and poly(vinyl chloride) (PVC) have been studied by means of Fourier transform — infrared attenuated total reflection (FT-IR ATR) spectroscopy. Phenolic hydroxyl groups and functional groups with a carbonyl group are present on the untreated and all oxidized edge surfaces. For all the surfaces, some of the phenolic hydroxyl groups are linked by hydrogen bonds to each other or functional groups with a carbonyl group, part of the carboxyl groups also being linked by hydrogen bonds to each other. Lactone, carboxyl, and quinone structure moieties are formed on the edge surface by the electrochemical treatment. Among the moieties, quinones are mainly introduced to the edge surface by the severe electrochemical treatment. Quinones are not present on the untreated and the plasma-treated edge surfaces. FT-IR ATR spectra provide evidence for the existence of hydrogen bonds between the > C = O groups present on the edge surface and PVC.     

Poly(ethylene glycol) interactions with alumina and silica powders determined via DRIFT

Diffuse reflection infrared spectroscopy (DRIFT) is used to determine interfacial interactions between poly(ethylene glycol) (PEG), alumina and silica powders. The interactions are created by grafting in high temperature and low moisture environments due to preferential adsorption between PEG and water. Under these grafting conditions, a shoulder appears on the C–O–C stretching band of the DRIFT spectrum. This is found to occur when PEG is in the presence of a hydrogen donor such as surface hydroxyls on alumina and silica. The shoulder is reported as an interaction band due to hydrogen bonding between the PEG etheric oxygen and the surface hydroxyls of alumina and silica. Specific band positions are measured when the PEG chain is interacting with alumina (1090 cm^–1), silica (1080 cm^–1), or water (1085 cm^–1).