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Summary: Surfaces of PTFE were modified by polychromatic UV irradiation in the presence of hydrazine vapors. The surfaces were characterized by FTIR and XP spectroscopy as well as by zeta‐potential and contact angle measurements. FTIR spectroscopy revealed that – in addition to the introduction of amino and hydrazinyl groups onto the PTFE surface – a partial hydrogenation of the CF units proceeds (generation of hydrocarbon units CH). This finding is backed by XPS results. A fraction of the photochemically modified PTFE layers is soluble in aqueous media, while hydrogenated units appear to be more stable. The determination of the zeta potential (ζ) of the PTFE surface showed a shift of the isoelectric point towards higher pH values as a result of the surface modification. The zeta potential vs. pH curves are shifting steadily towards more positive values at increasing duration of the N2H4/UV treatment. The analysis of the surface tension components of hydrazine‐modified PTFE indicates a strong increase of the Lifshitz‐Van der Waals components (γLW) and electron‐donor components (γ−) compared to untreated PTFE. These components change in different fashion after extraction of the PTFE surface with aqueous media. Finally it is shown that amino and hydrazinyl groups at the PTFE surface can be derivatized by polymer‐analogous reactions with isothiocyanates and anhydrides.Zeta‐potential versus pH plots of modified PTFE samples. Dependence on the UV irradiation time in the presence of hydrazine vapor. (○) 0 min; (▴) 30 min; (▾) 45 min; (♦) 70 min; (▪) 90 min; (•) 120 min.magnified imageZeta‐potential versus pH plots of modified PTFE samples. Dependence on the UV irradiation time in the presence of hydrazine vapor. (○) 0 min; (▴) 30 min; (▾) 45 min; (♦) 70 min; (▪) 90 min; (•) 120 min.

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SUMMARY: The surface of polystyrene was modified by the introduction of CN groups. This was achieved by irradiating the polymer with UV light (254 nm) in the presence of gaseous cyanogen bromide (BrCN). X-ray photoelectron spectroscopy (XPS) and FTIR analysis showed that after irradiation both Br and CN groups were covalently bound to the polymer surface. Quantitative XPS analysis revealed that upon prolonged irradiation every second monomer unit at the surface was modified with a CN group. It was demonstrated that photochemical techniques can be employed to attach specific functional groups onto polymer surfaces.

The effects of intravenous injections of the opiate antagonist naloxone (0.005-0.4 mg/kg body weight) on respiratory pattern, apnoea duration and frequency were investigated in six infants with severe sleep apnoea syndrome. Since several authors found elevated plasma- and CSF-levels of endogenous opioids (endorphines) in infants with sleep apnoea syndrome, we wanted to determine whether the impairment of the control mechanisms of respiration during sleep is due to an effect of endogenous opioids. Independent of the dose, naloxone did not exert any effect on respiratory pattern and occurrence of periodic apnoea. We were unable to prove that endorphines play a major role in pathogenesis of sleep apnoea syndrome in infancy and possibly in sudden infant death syndrome (SIDS). We speculate that elevated levels of endorphines reported by some investigators rather seem to be a consequence of hypoxic stress than a cause for sleep apnoeas.