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Diamond-like carbon (DLC) and silicon carbide (SiC) coatings are attractive because of low friction coefficient, high hardness, chemical inertness and smooth finish, which they provide to biomedical devices. Silicon wafers (Si waf ) and silicone rubber (Si rub ) plates were coated using plasmaenhanced chemical vapour deposition (PE-CVD) techniques. This article describes: 1-the characterization of modified surfaces using attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FTIR) and contact angle measurements, 2-the results of three in-vitro haemocompatibility assays. Coated surfaces were compared to uncoated materials and various substrates such as polymethylmethacrylate (PMMA), polyethylene (LDPE), polydimethylsiloxane (PDMS) and medical steel (MS). Thrombin generation, blood platelet adhesion and complement convertase activity tests revealed the following classification, from the most to the least heamocompatible surface: Si rub / DLC-Si rub / DLC-Si waf / LDPE/ PDMS/ SiCSi waf / Si waf / PMMA/ MS. The DLC coating surfaces delayed the clotting time, tended to inhibit the platelet and complement convertase activation, whereas SiC-coated silicon wafer can be considered as thrombogenic. This study has taken into account three events of the blood activation: coagulation, platelet activation and inflammation. The response to those events is an indicator of the in vitro haemocompatibility of the different surfaces and it allows us to select biomaterials for further in vivo blood contacting investigations.

SYNOPSISFilms of polyurethane were prepared by reaction of hydroxytelechelic polybutadienes carrying covalently bound quaternary ammonium salts with an aliphatic triisocyanate. These coatings exhibited high biocidal activity against Gram-positive and Gram-negative bacteria, yeasts, and moulds. It was found that many parameters controlled the bioactivity such as the time of contact between films and bacteria, the [ NCO] / [ OH] ratio used to prepare the cured polyurethane, the concentration of quaternary ammonium salts in the coating, and the length of the alkyl chain from C8 to CI6 linked to the quaternary nitrogen atom. A secondary phenomenon of diffusion only observed with the shorter alkyl chains ( C8 and Clo) was shown to be due to synthesis residues. After these water-soluble impurities are eliminated, the biocidal activity remains excellent: then it is due only to a contact polymer bacteria. 0 1993 John Wiley & Sons, Inc.

SYNOPSISHydroxytelechelic polybutadienes carrying covalently bound quaternary ammonium salts were successfully synthesized in three steps. The first one was the preparation of 1-(N,Ndimethylaminopropyl) 1,1,3,3-tetramethyldisiloxane (MLA) by hydrosilylation. The addition occurred mainly in the terminal position of the double bond, but isomers were formed in small proportion ( a n isomer resulting from an inverse addition and an isomer resulting from a n isomerization of the double bond). The proportion of these isomers increased with the concentration of catalyst ( HzPtCls). Similar results were obtained with a Pt ( 0 ) -divinyltetramethyldisiloxane complex (Pt,DVDS) . The second step was the grafting of M;A onto the 1,2-units of a hydroxytelechelic polybutadiene by hydrosilylation. The yield of the reaction was higher than 90% and the OH functionality decreased slightly. Here again, different platinum catalysts were compared initial rates were higher with Pt,DVDS, but the final yields were better with HzPtCls. The last step was the quaternization of the pendant tertiary amino groups in methanol with alkyl bromides from COH17Br to CI6&Br. The yield of the reaction was higher than 90% and the OH functionality was not modified.

SYNOPSISPolyurethane coatings prepared from hydroxytelechelic polybutadiene with pendant quaternary ammonium salts (QAS) are able to kill microorganisms only by contact. In order to determine the time of protection against microorganisms, these biocidal polymers were submitted to various ageing conditions. The activity remained constant after exposure to a very high number of bacteria (Escherichia coli) . Nevertheless immersion in water caused a slow decrease of activity with time whatever the QAS examined (-N+R,R' with R = Me or Bu and R' = n-octyl to n-hexadecyl). The phenomenon can be analysed in two stages. The first one, short (5-10 days) and limited, is due to the diffusion of a watersoluble synthesis residue. At the end of this period, the samples are still active and the activity is only due to a contact polymer-bacteria. The second stage is much slower and is accompanied by a transformation of QAS in amine. This is attributed to an equilibrium between QAS, amine, and alkyl bromide slowly shifted toward the formation of amine because of a weak solubility of alkyl bromide in water. Increasing the lipophilicity and bulkiness of the &AS substituents improves the durability of the biocidal activity. Some samples still exhibit a good activity after more than 1 year of ageing in harsh conditions. 0 1993 John Wiley & Sons, Inc. I NTRO DUCT IONQuaternary ammonium salts (QAS) possessing at least one alkyl substituent of at least eight carbon atoms are able to kill microorganisms such as bacteria, fungi, and moulds by interacting with the cell membrane.' QAS of low molar mass are widely used as "cationic disinfectants." Water-soluble polymers bearing QAS as lateral groups linked through nonhydrolysable covalent bonds exhibit bactericidal and fungicidal a~t i v i t y .~,~ It has been shown that insoluble polymers containing the same type of QAS are also efficient in the solid ~t a t e .~-~ In the preceding papers of this series, the synthesis of hydroxytelechelic polybutadienes bearing QAS at the extremity of a siloxanic side chain were described8 and the biocidal properties of PU-films based on these polyols were ~t u d i e d .~The coatings present a good ef-