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Diamond-like carbon (DLC) is being considered for widespread clinical use as a surface coating for cardiovascular devices. We synthesized fluorinated DLC (F-DLC) coatings in order to create a more hydrophobic surface with improved antithrombogenicity and flexibility when compared with conventional DLC coatings by combining the inertness of DLC films with the advantage of fluorination. The purpose of this study was to evaluate the in vitro hemocompatibility and in vivo biocompatibility of the F-DLC coating for medical devices. The in vitro whole blood model confirmed that platelet loss was lower in the F-DLC group than in the noncoated group (SUS316L), which suggests the adhesion of a smaller number of platelets to F-DLC-coated materials. Furthermore, the biomarkers of mechanically induced platelet activation (beta-thromboglobulin) and activated coagulation (thrombin-antithrombin-three complex) were markedly reduced in the F-DLC-coated group. In vivo rat implant model studies revealed no excessive local and systemic inflammatory responses in the F-DLC group. The thickness of the fibrous tissue capsule surrounding the F-DLC-coated disk was almost equal to that of the noncoated SUS316L disk, which has the favorable biocompatibility for metallic implant materials. F-DLC coating thus appears to be a promising candidate for use as a coating material in blood-contacting devices.

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ABSTRACT:Fabrication of poly(p-oxybenzoyl) (POB) nanowhiskers was examined by using reaction-induced crystallization of oligomers during the polymerization of p-acetoxybenzoic acid in liquid paraffin. Width of the POB whiskers was susceptible to polymerization temperature and it was efficiently controlled by a change in temperature during the polymerization. Increase in polymerization temperature just after nucleation (Han) reduced the degree of super saturation of oligomers () resulting in the depression of the width increase by the crystallization of oligomers on side surface of the whiskers. Temperature drop just before nucleation (Cbn) enhanced the value of resulting in the generation of much more nuclei having the smaller width. On the basis of these results, the combination of these two methods Han and Cbn afforded the whiskers having the smallest width, and the POB nanowhiskers were prepared of which the width and the length were 190 nm and 18.6 mm, respectively. [DOI 10.1295/polymj.37.906] KEY WORDS Poly(p-oxybenzoyl) / Nanowhisker / Polyester / Crystallization / Oligomer / One-dimensional nanoscale materials such as nanowhiskers, nanofibers, nanotubes and nanobelts are attracting attention because of their intriguing chemical and physical properties, and actively studied to create novel devices.1-3 Among them, nanowhiskers of inorganic compounds are recently developed for electronic/optoelectronic devices and sensors.4,5 Polymer nanowhiskers and nanofibers have also been received much attention as very interesting one-dimensional materials.6-8 The polymer nanofibers are usually fabricated by the polymer nano-processing technologies represented by electrospinning 9-15 or the self-assembling of polymer molecules. [16][17][18] Template syntheses have been developed involving the introduction of the materials within channels of templates. [19][20][21][22][23][24][25] In contrast to this, the fabrication of polymer nanowhiskers is more difficult, and to our knowledge C 60 whisker is the only nanowhisker prepared by a liquid-liquid interfacial precipitation under light illumination. 26Rigid-rod aromatic polymers are characterized by the unique combination of thermal and mechanical properties, which makes them useful candidates for high performance materials. 27 Although the nanowhiskers and nanofibers of rigid aromatic polymers have a bright prospect of valuable industrial materials, they show usually neither solubility nor feasibility and hence it is difficult to process them by the previous fabrication procedures. The fabrication method of them has not been reported so far.Poly(p-oxybenzoyl) (POB) which is a wholly aromatic polyester possesses the aforesaid antagonistic problem between properties and processability. In order to overcome this problem, we have been studying the morphology control of POB by using crystallization of oligomers during polymerization, and succeeded in obtaining POB whiskers by the polymerization of p-acetoxybenzoic acid (ABA) in liquid paraffin (LPF) with the elimination of acet...

The yielding behavior of the melts of poly(n-butyl)acrylate rubber-particles with various cross-link densities in feed (c x ) is investigated by the creep and recovery tests, and the large amplitude oscillation (LAOS) measurements. The measurements reveal the presence of a yield stress for the onset of plastic flow. The equilibrium shear modulus (G 0 ), which is measured at the small stresses below the yield stress, increases with an increase in c x as G 0 ~ c x 0.5 . The yield strain (g c ≈ 2 × 10 -2 ) is almost independent of c x and temperature. The c x -insensitive g c is qualitatively similar to the earlier results for the highly dense suspensions of micro-hydrogels.