Thin films of poly(3-hydroxybutyrate) were modified by microwave ammonia plasma treatment. The results of the modification were studied by means of contact angle goniometry, ellipsometry, Fourier transform infrared-attenuated total reflection spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. To prove the presence of amino groups on the poly(3-hydroxybutyrate) surface, chemical labeling with 4-trifluoromethyl benzaldehyde was performed before X-ray photoelectron spectroscopy analysis. Under the applied plasma conditions, a hydrophilic surface with a good long-term stability was obtained.

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The electrokinetic charge density and the dissociation behavior of the surface carboxylic acid groups in binary self-assembled monolayers (SAMs) of 11-mercaptoundecanoic acid (MUA)/11-mercapto-undecanol (MUOH), and 16-mercaptohexadecanoic acid (MHA)/hexadecanethiol (HDT) on planar gold surfaces were studied by streaming potential and streaming current measurements in aqueous electrolyte solutions. For both two-component SAMs, the isoelectric point decreased with lower surface fractions (<0.25) of the carboxyterminated alkanethiols, indicating that electrostatic interactions of the acid anions cause the significantly attenuated acidity of high coverage COOH-terminated SAMs. This agrees well with theoretical considerations on the influence of electrostatic energy on the interfacial acid-base equilibrium. Diffuse layer charge densities calculated from zeta potentials in monovalent electrolyte solutions show that the countercharge in the diffuse layer increases with decreasing surface charge but is due to inner layer counterion adsorption still significantly lower than predicted by the standard Gouy-Chapman theory. In the case of bivalent counterions, ion binding models successfully describe the observed electrokinetic potentials.

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We report the fabrication of a molecular surface coating from an epoxy-functionalized hyperbranched polyester functionalized by secondary epoxy groups. These groups were presented in the fraction of terminal branches of the hyperbranched shell with the ratio of epoxy-containing branches and alkyl branches of 1:2. We demonstrated that a uniform monolayer with the thickness of 4.5 nm could be fabricated by melt grafting of functionalized hyperbranched polymers to a bare silicon surface. Steric constraints imposed by the chemical attachment of alkyl and epoxydized branches to a single core prevented microphase separation of dissimilar segments and allowed the fabrication of uniform monolayers with surface exposure of the functional groups and high adhesion. An estimated 3-4 epoxy groups per molecule were located in the uppermost surface layer and provided residual functionality sufficient to graft another polymer layer. Grafted layers were extremely robust and sustain high compression and shear stresses while possessing high elasticity.