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An amphiphilic triblock surface-active block copolymer (SABC) possessing ethoxylated fluoroalkyl side chains was synthesized through the chemical modification of a polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene polymer precursor. Bilayer coatings on glass slides consisting of a thin layer of the amphiphilic SABC spray coated on a thick layer of a polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) thermoplastic elastomer were prepared for biofouling assays with the green alga Ulva and the diatom Navicula. Dynamic water contact angle analysis and X-ray photoelectron spectroscopy (XPS) were used to characterize the surfaces. Additionally, the effect of the Young's modulus of the coating on the release properties of sporelings (young plants) of the green alga Ulva was examined through the use of two different SEBS thermoplastic elastomers possessing modulus values of an order of magnitude in difference. The amphiphilic SABC was found to reduce the settlement density of zoospores of Ulva as well as the strength of attachment of sporelings. The attachment strength of the sporelings was further reduced for the amphiphilic SABC on the "low"-modulus SEBS base layer. The weaker adhesion of diatoms, relative to a PDMS standard, further highlights the antifouling potential of this amphiphilic triblock hybrid copolymer.

Thermoplastic elastomers (TPEs) that are soft at low extension yet strong at large extension are of great importance in a variety of technological applications. In ABA-triblock architectures, both the overall molecular weight and the composition of the glassy A-blocks correlate with TPE strength. The design space of current TPEs based on linear ABA triblock copolymers (e.g., polystyrene-b-polybutadiene-b-polystyrene) is restricted by the accessibility of the order−disorder transition temperature, limiting the molecular weight, and restricted by the maximum volume fraction for which glassy A-blocks will form discrete domains. Using self-consistent-field theory (SCFT), we designed in silico two new, nonlinear TPE architectures that significantly relax the composition restriction: radial (ABA′) n and A(BA′) n miktoarm star-block copolymers with chemically identical, but unequal, molecular weight A-blocks. Through a balance of end-block bidispersity, block extraction from the interface, and architectural asymmetry, these molecular architectures are able to stabilize phases with discrete A-rich domains at remarkably high overall A-monomer compositions (f A). In some cases the maximum f A achieved for phases with discrete A-rich domains surpasses twice that of conventional linear ABA TPEs.

Two series of amphiphilic triblock surface active block copolymers (SABCs) were prepared through chemical modification of two polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene ABC triblock copolymer precursors. The methyl ether of poly(ethylene glycol) [M(n) approximately 550 g/mol (PEG550)] and a semifluorinated alcohol (CF(3)(CF(2))(9)(CH(2))(10)OH) [F10H10] were attached at different molar ratios to impart both hydrophobic and hydrophilic groups to the isoprene segment. Coatings on glass slides consisting of a thin layer of the amphiphilic SABC deposited on a thicker layer of an ABA polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene thermoplastic elastomer were prepared for biofouling assays with algae. Dynamic water contact angle analysis, X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) measurements were utilized to characterize the surfaces. Clear differences in surface structure were realized as the composition of attached side chains was varied. In biofouling assays, the settlement (attachment) of zoospores of the green alga Ulva was higher for surfaces incorporating a large proportion of the hydrophobic F10H10 side chains, while surfaces with a large proportion of the PEG550 side chains inhibited settlement. The trend in attachment strength of sporelings (young plants) of Ulva did not show such an obvious pattern. However, amphiphilic SABCs incorporating a mixture of PEG550 and F10H10 side chains performed the best. The number of cells of the diatom Navicula attached after exposure to flow decreased as the content of PEG550 to F10H10 side chains increased.

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Surface active triblock copolymers (SABC) with mixed polyethylene glycol (PEG) and two different semifluorinated alcohol side chains, one longer than the other, were blended with a soft thermoplastic elastomer (TPE), polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). The surface composition of these blends was probed by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The surface reconstruction of the coatings in water was monitored qualitatively by dynamic water contact angles in air as well as air bubble contact angle measurements in water. By blending the SABC with SEBS, we minimize the amount of the SABC used while achieving a surface that is not greatly different in composition from the pure SABC. The 15 wt % blends of the SABC with long fluoroalkyl side chains showed a composition close to that of the pure SABC while the SABC with shorter perfluoroakyl side chains did not. These differences in surface composition were reflected in the fouling-release performance of the blends for the algae, Ulva and Navicula.

Phase contrast produced in the electron microscope by defocus techniques has been used to obtain the first unstained images of styrene-isoprene and styrene-butadiene diblock and triblock copolymers. Theoretical image calculations based on square-wave and circular cross section one-dimensional models were used to demonstrate the effects of mean inner potential difference, interface width, and microscope optics on resultant images. Experimental phase contrast images of microtomed block copolymers with ordered lamellar, cylindrical, and disordered spherical morphologies were in good agreement with theory and with experimental scattering contrast images (osmium tetraoxide stain). Repeat periods in the ordered morphologies were found to be independent of the microscope parameters as theoretically predicted. Calculations show that the compositional profile across the interface between the polymer phases will not be easily measured from experimental phase contrast images because of the smoothing effect of limited electron beam coherence. The phase contrast technique is, however, sufficient to visualize the phase-separated regions of polymers of quite similar atomic composition and/or density, eliminating the need for chemical modification of one or both of the polymers.

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