Argon plasma irradiation of polypropylene

a b s t r a c t Polypropylene samples were exposed to argon plasma discharge and the changes of the PP surface properties were studied by different methods. Surface wettability was derived from contact angle measured by standard goniometry and chemical structure of the plasma modified PP was studied using X-ray photoelectron spectroscopy (XPS) and by Rutherford backscattering spectroscopy (RBS), surface morphology and roughness of samples using AFM. Zeta potential of pristine and modified PP was determined with the SurPASS. The presence of incorporated oxygen in the PP surface layer, about 60 nm thick, was observed in RBS spectra. Oxygen concentration is a decreasing function of the depth. With progressing aging time the oxygen concentration on the PP surface decreases. Plasma treatment results in a rapid decrease of the contact angle, which increases again with increasing aging time. In XPS measurement the oxygen containing structures, created by the plasma treatment, were found on the very surface of the modified PP and the zeta potential being changed too. The significant difference in zeta potential between pristine and plasma treated PP clearly indicates that the plasma treatment leads to a more hydrophilic PP surface

"Soft and rigid" dithiols and Au nanoparticles grafting on plasma-treated polyethyleneterephthalate

Surface of polyethyleneterephthalate (PET) was modified by plasma discharge and subsequently grafted with dithiols (1, 2-ethanedithiol (ED) or 4, 4'-biphenyldithiol) to create the thiol (-SH) groups on polymer surface. This "short" dithiols are expected to be fixed via one of -SH groups to radicals created by the plasma treatment on the PET surface. "Free" -SH groups are allowed to interact with Au nanoparticles. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and electrokinetic analysis (EA, zeta potential) were used for the characterization of surface chemistry of the modified PET. Surface morphology and roughness of the modified PET were studied by atomic force microscopy (AFM). The results from XPS, FTIR, EA and AFM show that the Au nanoparticles are grafted on the modified surface only in the case of biphenyldithiol pretreatment. The possible explanation is that the "flexible" molecule of ethanedithiol is bounded to the activated PET surface with both -SH groups. On the contrary, the "rigid" molecule of biphenyldithiol is bounded via only one -SH group to the modified PET surface and the second one remains "free" for the consecutive chemical reaction with Au nanoparticle. The gold nanoparticles are distributed relatively homogenously over the polymer surface

The Influence of Surface Treatment and Activation of Thin Film Composite Membranes with Plasma Discharge and Determination of Their Physicochemical Properties.

In this work we have focused on the surface treatment and activation of membranes (73 AC and 82 V) with plasma discharge and determination of their physicochemical properties. The surface morphology, wettability, zeta potential of pristine and plasma- treated membranes were tested and compared

The relationship between physical activity, self-perceived health, and cognitive function in older adults

There are consistent associations between physical activity and self-perceived health. However, it is not clear whether associations between self-perceived health and participation in physical activity could be accounted for by associations with cognitive function. In the present study, we examined whether associations between physical activity and cognitive functioning could explain the variability between physical activity and self-perceived health. A sample of 204 older adults performed three cognitive tests selected from the Vienna test system battery: The Determination, Cognitrone, and Visual Memory tests. These tests measure general processing speed, attention, and visual memory, respectively. Participants also completed the 12-item Short Form Health Questionnaire SF-12 to measure perceived health, and the Physical Activity Survey for the Elderly to measure physical activity. Linear regressions and the PROCESS macro for SPSS were used to test our hypotheses. Consistent with our hypotheses, processing speed accounted for significant variance in the relationship between physical activity and self-perceived health. This suggests that cognitive processing speed might be an indirect path by which physical activity relates to enhanced health perceptions. The results demonstrate that associations between physical activity and self-perceptions of health are related to a fundamental cognitive process

Thermally induced wrinkling of Poly-L-lactic Acid with palladium nanolayers

Poly-L-lactic acid has lately attracted a lot of scientific interest as this material is capable of forming complex nanostructures by self organization due to wrinkling instability. This process is induced thermally on samples which were plasma-treated, sputtered with metal layers or both and therefore it offers many parameters for tweaking to achieve desired material properties. This paper focuses on poly-L-lactic acid samples coated with palladium nanolayers. After annealing these samples develop sharp wrinkles with size directly dependent on thickness of sputtered metal layer as observed by means of atomic force microscopy. Sheet resistance was also measured and has shown significant changes of electrical properties dependent both on palladium layer thickness and thermal treatment. X-ray photoelectron spectroscopy has shown that annealing does not change metal concentration on the surface of the sample it only causes rearrangement of the palladium. These data were important for choosing viable candidates for biocompatibility tests that are also presented in the paper. Annealed samples with thin palladium layers have shown significant improvement over polystyrene mock and even significant improvement of adhesion and short term proliferation (up to 60 hours) over pristine poly-L-lactic acid