20 research outputs found

    Surfaces of fluorinated polymer systems

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    Scrotal metastases from colorectal carcinoma: a case report

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    A 72-year-old man presented with a two month history of rectal bleeding. Colonoscopy demonstrated synchronous lesions at 3 cm and 40 cm with histological analysis confirming synchronous adenocarcinomata. He developed bilobar hepatic metastases while undergoing neoadjuvant chemoradiotherapy. Treatment was complicated by Fournier's gangrene of the right hemiscrotum which required surgical debridement. Eight months later he re-presented with an ulcerating lesion on the right hemiscrotum. An en-bloc resection of the ulcerating scrotal lesion and underlying testis was performed. Immunohistological analysis revealed metastatic adenocarcinoma of large bowel origin. Colorectal metastasis to the urogenital tract is rare and here we report a case of rectal carcinoma metastasizing to scrotal skin

    P[CF3(CF2)5CH2MA-co-MMA] and P[CF3(CF2)5CH2MA-co-BA] Copolymers: Reactivity Ratios and Surface Properties

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    This study aimed at reducing the surface energy of coatings by copolymerization of commonly used monomers with fluorine-containing monomers. Copolymers of 1,1-dihydroperfluoroheptyl methacrylate (FHMA) and methyl methacrylate (MMA) or butyl acrylate (BA) are prepared by low-conversion polymerization in solution. Using 1H-NMR data and nonlinear least-squares data fitting, reactivity ratios of these systems at 80°C are determined to be rFHMA = 1.31, rMMA = 0.76, and rFHMA = 3.15, rBA = 0.38, respectively. We assume that the penultimate unit effect plays an important role in these systems. Introduction of the perfluoroalkyl side chain lowers the polymer surface energy significantly; copolymers of MMA and FHMA show a reduction in total surface energy of about 50 % at a content of 15 mol % FHMA as compared with pure PMMA. The attainable reduction in surface energy is much larger than with, for example, Teflon. This is due to the preferential adsorption of the - CF3 groups of the fluoroalkyl side chain, if compared to that of the - CF2 - groups of Tefl

    Quantification of fluorine density in the outermost atomic layer

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    The outermost at. layer of perfluorinated thiol monolayers on gold and poly(tetrafluoroethylene) (PTFE) is analyzed by low-energy ion scattering. Abs. quantification of fluorine d. in this layer was achieved after calibrating the fluorine signal with a freshly cleaved LiF(100) single crystal. The fluorine d. of monolayers of a C8F17-thiol on gold was 1.48 * 1015 F atoms/cm2, whereas for PTFE a value of 1.24 * 1015 F atoms/cm2 was obsd. This difference was explained by the different tilt angles of the thiol on gold and PTFE chains with respect to the surface normal. Both a configurational and a mol. interpretation on the perfluorinated thiol monolayer on gold are given

    Thermodynamically controlled surface segregation of perfluoroalkyl-end-capped PMMA as investigated by low energy ion scattering (LEIS)

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    Low MW PMMA prepd. by atom transfer radical polymn. (ATRP) was blended with a perfluoroalkyl-end-capped PMMA (Rf-PMMA) synthesized also by ATRP. Thin films were prepd. by spin casting the polymer blend solns. in toluene. Fluorinated species became enriched at the film surface, evidenced by increased contact angles for both water and hexadecane. The temp.-dependent fluorine concn. in the outermost one layer was quant. detd. by low energy ion scattering (LEIS). The fluorine concn. decreased significantly upon the increase of the temp. when the temp. was above the glass transition temp. of polymers. The surface segregation of fluorinated species at temps. above the Tg of polymers appears to be thermodynamically controlled. [on SciFinder (R)

    Low surface energy films based on partially fluorinated isocyanates: the effects of curing temperature

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    Self-stratification strategy can be used to prepare films in which both bulk and surface properties can be optimized. By using this approach, only a very small quantity of fluorinated species is needed to generate a surface with low surface energy. When cross-linking is involved during film formation, we are dealing with a competition behavior between the diffusion of fluorinated species and the formation of cross-linked network. In this study low surface energy polymeric films were prepared on the basis of partially fluorinated polyisocyanates, in combination with hydroxyl-end-capped three-armed solventless liquid oligoesters and modified hyperbranched polyesters. At a fluorine concentration of only 0.5 wt.%, contact angles of water and hexadecane can reach 120° and 80°, respectively. A surface energy as low as 10¿15 mN/m can be obtained upon the addition of less than 1 wt.% of fluorine in the films. It was shown, from real time ATR-FTIR and contact angle measurements, that the curing temperatures demonstrated significant effects on the cross-linking rate as well as on the wettability of the films

    Low surface energy films based on partially fluorinated isocyanates: the effects of curing temperature

    No full text
    Self-stratification strategy can be used to prepare films in which both bulk and surface properties can be optimized. By using this approach, only a very small quantity of fluorinated species is needed to generate a surface with low surface energy. When cross-linking is involved during film formation, we are dealing with a competition behavior between the diffusion of fluorinated species and the formation of cross-linked network. In this study low surface energy polymeric films were prepared on the basis of partially fluorinated polyisocyanates, in combination with hydroxyl-end-capped three-armed solventless liquid oligoesters and modified hyperbranched polyesters. At a fluorine concentration of only 0.5 wt.%, contact angles of water and hexadecane can reach 120° and 80°, respectively. A surface energy as low as 10¿15 mN/m can be obtained upon the addition of less than 1 wt.% of fluorine in the films. It was shown, from real time ATR-FTIR and contact angle measurements, that the curing temperatures demonstrated significant effects on the cross-linking rate as well as on the wettability of the films
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