Surface Modification via Chain End Segregation in Polymer Blends

Abstract

We have explored the use of chain end segregation as a means of controlling the properties of a polymer surface. Thin film blends of homopolystyrene (PS) and PS synthesized with low-energy oligotetrafluoroethylene chain ends (PS-TFE) were studied using neutron reflectivity. The fraction of PS-TFE that localizes near the surface was found to increase as a function of its concentration in the blend. Contact angle measurements indicate corresponding reductions in the surface tension due to the surface localization of the TFE chain ends. For a 10% blend of 6000 mol wt PS-TFE in 3 × 105 mol wt PS, the surface coverage of fluorocarbon ends was found to be >20%. A free energy model of the blends gives good qualitative agreement with the experimental results.

X-ray Spectromicroscopy Study of Protein Adsorption to a Polystyrene−Polylactide Blend

“…Since PETA is more hydrophobic than PEO [26], PETA should have lower surface free energy and would be expected to segregate to the surface [28,29]. Furthermore, the molecular weight difference between PETA and PEO should also affect the surface composition with the lower molecular weight PETA segregating to the surface [30]. These quantitative results show that at a crosslinker concentration > 5 wt-%, the PEO surface begins to lose its non-fouling properties and begins to adsorb protein.…”

Surface segregation of conformationally asymmetric polymer blends

“…The first one is given by graphs b and c, in which the external line associated with 1 and which renormalizes the one-polymer propagators in (35). The second part, with the external line associated with V ext AB , together with the graph a describes the fluctuations corrections to the concentration profile.…”

Wettability control of photocatalytic crystal layers by hydrophobic coating and subsequent UV light irradiation

“…For example, FAS molecule has the lower LUMO and HOMO so that these low energy levels lead to the lowest Fermi level (-0.20651 hartree). The nanotextured substrates were placed together with a glass cup filled with 0.1 cm 3 organosilane liquid into a 300 cm 3 Teflon container. The container was sealed with a cap and placed for 1 h in an oven maintained at 150°C.…”

“…Increasing a surface's water repellency can be achieved by both decreasing the free energy between it and water, and increasing its roughness [1,2]. Incorporating fluorine atoms, which have a small atomic radius and high electronegativity, can achieve a low surface free energy [3,4]. An ideally flat surface covered with regularly aligned and closely packed CF 3 groups shows a water contact angle of about 120° [4].…”