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A unique combination of surface chemistry and self-assembly of amphiphilic block copolymers was employed to obtain-for the first time-solid-supported biomimetic polymer bilayers. An organized monolayer from sulfur-functionalized poly(butadiene)-b-poly(ethylene oxide) was covalently attached to ultrasmooth gold upon Langmuir-Blodgett transfer. Hydrophobic interactions, on the other hand, were exploited to attach the second monolayer. As a result, we obtained a homogeneous hydrophilichydrophobic-hydrophilic structure, similar to supported lipid bilayers by architecture, stability and fluidity. Our polymer bilayers, however, outperform such lipid membranes with regard to tunability of thickness and stability in gaseous environments. As characterized by surface analysis tools (AFM, SPR), solid-supported polymer membranes are smooth with a thickness of ca. 11 nm, resistant to rinsing with aqueous solutions and stable upon drying and rehydration. These properties could be attractive for nanotechnological applications, such as immobilization of functional molecules or nanoparticles, sensor development or preparation of chemically responsive functional surfaces.

The behavior of binary monolayers from PMOXA-PDMS-PMOXA triblock copolymers and alamethicin, an antimicrobial peptide, was investigated in the context of formation of novel biocomposite nanostructured materials. The properties of mixed monolayers were studied by surface pressure-area isotherms and Brewster angle imaging. As reported previously, functionality of alamethicin relies on its aggregation properties in lipid mono-and bilayers. This is also the case in polymer matrixes, however, here the mixing properties differ from lipid-peptide systems due to the polymers' structural specificity. The peptide influence on the polymer films is provided in detail for the first time, and supported by the compressibility data to asses the elastic properties of such composite membranes.

The thermotropic sphere-to-rod transition of nonionic surfactants was characterized in terms of a large set of parameters: the transition temperature and width, the partial volume, coefficient of thermal volume expansion, enthalpy, isobaric heat capacity, and structural parameters, such as radius of gyration and hydrodynamic radius. Data were recorded as a function of concentration of surfactants in H2O and in D2O. To this end, pressure perturbation calorimetry (PPC), small angle neutron scattering (SANS), dynamic light scattering (DLS), differential scanning calorimetry (DSC), and isothermal titration calorimetry (ITC) were applied in a study of aqueous solutions containing myristyl, tridecyl, and lauryl maltoside and heptaethyleneglycoltetradecyl ether (C14EO7). Small changes in the thermodynamic and volumetric parameters (e.g., the partial volume change is approximately +2 per thousand) are discussed in detail as the result of three effects governing the transition. (i) Reduction of the water accessible hydrophobic surface area (ASA(ap)) drives the transition. (ii) Shrinking in headgroup size by thermal dehydration triggers the transition. (iii) Hypothesized gradual ordering of the chains may control the effect of chain length on the transition.

The self-assembly of the amphiphilic block copolymer poly(n-butyl methacrylate)-block-poly[2-(dimethylamino)ethyl methacrylate] at the air-water interface has been investigated at different pH values. Similar to Rehfeldt et al. (J. Phys. Chem. B 2006, 110, 9171), the subphase pH strongly affects the monolayer properties. The formation of calcium phosphate beneath the monolayer can be tuned by the subphase pH and hence the monolayer charge. After 12 h of mineralization at pH 5, the polymer monolayers are still transparent, but transmission electron microscopy (TEM) shows that very thin calcium phosphate fibers form, which aggregate into cotton ball-like features with diameters of 20 to 50 nm. In contrast, after 12 h of mineralization at pH 8, the polymer film is very slightly turbid and TEM shows dense aggregates with sizes between 200 and 700 nm. The formation of calcium phosphate is further confirmed by Raman and energy dispersive X-ray spectroscopy. The calcium phosphate architectures can be assigned to the monolayer charge, which is high at low pH and low at high pH. The study demonstrates that the effects of polycations should not be ignored if attempting to understand the colloid chemistry of biomimetic mineralization. It also shows that basic block copolymers are useful complementary systems to the much more commonly studied acidic block copolymer templates.

Amphiphilic poly(acrylic acid)-block-poly(n-butylacrylate) block copolymer films at the air-water interface have been mineralized with calcium phosphate. The polymers form stable monolayers at the free surface. Their stability is virtually independent of ion strength or pH changes in the subphase. The outcome of calcium phosphate crystallization depends on the calcium and phosphate concentrations, the stirring rate of the subphase, and the subphase pH. At low calcium and phosphate concentrations (2 mM), uniform polymer-calcium phosphate hybrid films form. Higher calcium and phosphate concentrations yield less ordered films, which often contain large blocks of material beneath the polymer monolayer. Occasionally, also filaments similar to samples described by Peytcheva et al. (Colloid Polym. Sci., 2002, 280, 218) are observed. Films mineralized at pH values below ca. 6 contain particles that are a few nanometers apart and the resulting films retain some flexibility. Films grown above pH 6 have a higher degree of mineralization. They are stiff and tend to break upon mechanical stress. Overall, the paper illustrates that low calcium phosphate supersaturation in the subphase and a well-defined (but not crystalline) interface are crucial for controlling calcium phosphate mineralization. As a result, the current study could serve as a model for biological mineralization which is more closely related to Nature than films made from e.g. detergents or low molecular mass compounds.

The self‐assembly of amphiphilic calix[4]arenes with either a carboxylic acid or a trimethyl ammonium head group and different alkyl chains in aqueous solution was investigated. The carboxylated calixarene forms vesicles in dilute solution and stable monolayers on water. In contrast, the ammonium head group provides high water solubility with no observed aggregation. At high concentrations, all calixarene amphiphiles form lyotropic liquid crystals.

The self-assembly of the amphiphilic block copolymer poly(butadiene)-block-poly[2-(dimethylamino)ethyl methacrylate] at the air-water interface and the mineralization of the monolayers with calcium phosphate was investigated at different pH values. As expected for polyelectrolytes, the subphase pH strongly affects the monolayer properties. The focus of the current study, however, is on the effect of an oscillating (instead of a static) polymer monolayer on calcium phosphate mineralization. Monitoring of the surface pressure vs. mineralization time shows that the monolayer is quite stable if the mineralization is performed at pH 8. In contrast, the monolayer at pH 5 shows a measurable decrease of the surface pressure already after ca. 2 h of mineralization. Transmission electron microscopy reveals that mineralization at low pH under constant oscillation leads to small particles, which are arranged in circular features and larger entities with holes of ca. 200 nm. The larger features with the holes disappear as the mineralization is continued in favor of the smaller particles. These grow with time and form necklace-like architectures of spherical particles with a uniform diameter. In contrast, mineralization at pH 8 leads to very uniform particle morphologies already after 2 h. The mineralization products consist of a circular feature with a dark dot in the center. The increasing contrast of the precipitates in the electron micrographs with mineralization time indicates an increasing degree of mineralization vs. reaction time. The study therefore shows that mechanical effects on mineralization at interfaces are quite complex.