Novel methods for affixing functional proteins on surfaces with high areal density have the potential to promote basic biological research as well as various bioarray applications. The use of polymeric templates under carefully balanced thermodynamic conditions enables spontaneous, self-assembled protein immobilization on surfaces with spatial control on the nanometer scale. To assess the full potential of such nanometer-scale protein platforms in biosensing applications, we report for the first time the biological activity of proteins on diblock copolymer platforms. We utilized horseradish peroxidase, mushroom tyrosinase, enhanced green fluorescent protein, bovine immunoglobulin G, fluorescein isothiocyanate conjugated anti-bovine IgG, and protein G as model systems in our protein activity studies. When specific catalytic functions of HRP and MT, immobilized on selective domains of microphase-separated PS-b-PMMA, are evaluated over a long period of time, these enzymes retain their catalytic activity and stability for well over 3 months. By performing confocal fluorescence measurements of self-fluorescing proteins and interacting protein/protein systems, we have also demonstrated that the binding behavior of these proteins is unaffected by surface immobilization onto PS-b-PMMA diblock copolymer microdomains. Our polymer platforms provide highly periodic, high-density, functional, stable surface-bound proteins with spatial control on the nanometer scale. Therefore, our diblock copolymer-guided protein assembly method can be extremely beneficial for high-throughput proteomic applications.

It is believed that the optimal morphology of an organic solar cell may be characterized by cocontinuous, interpenetrating donor and acceptor domains with nanoscale dimensions and high interfacial areas. One well-known equilibrium morphology that fits these characteristics is the bicontinuous microemulsion achieved by the addition of block copolymer compatibilizers to flexible polymer–polymer blends. However, there does not exist design rules for using block copolymer compatibilizers to produce bicontinuous microemulsion morphologies from the conjugated polymer/fullerene mixtures typically used to form the active layer of organic solar cells. Motivated by these considerations, we use single chain in mean field simulations to study the equilibrium phase behavior of semiflexible polymer + flexible–semiflexible block copolymer + solvent mixtures. Based on our results, we identify design rules for producing large channels of morphologies with characteristics like that of the bicontinuous microemulsion.

The bicontinuous microemulsion (BμE) phase is an equilibrium morphology characterized by cocontinuous domains, high interfacial areas, and nanoscale domain dimensions. These characteristics make the BμE potentially suitable for use in organic photovoltaic applications. Here, we use a combination of simulations and experiments to investigate the equilibrium morphologies formed by a ternary blend of conjugated polymer, all-conjugated diblock copolymer, and fullerene derivative PCBM. Using coarse-grained simulations, we identify the blend compositions that are most likely to result in donor/acceptor morphologies resembling the BμE. Experimentally, we probe these compositions through transmission electron microscopy and grazing-incidence X-ray scattering measurements. We demonstrate that all-conjugated block copolymer additives can be used to produce thermally stable, cocontinuous donor/acceptor morphologies at higher additive contents and longer annealing times than previously reported. These results demonstrate that conjugated BCP compatibilizers can be used as a means to achieve equilibrium, cocontinuous morphologies in donor/acceptor blends.O rganic solar cells (OSCs) based on the conjugated polymer/PCBM blend boast the shortest expected energy payback time among various photovoltaic technologies. 1 However, two of the primary challenges still limiting the marketability of these devices are (i) the lower device efficiency of the OSC relative to the more conventional silicon-based solar cell and (ii) the long-term thermal instability of the device active layer. 2 Indeed, high performance organic solar cells are typically based on kinetically determined morphologies that degrade upon thermal annealing. In contrast, the achievement of equilibrium donor/acceptor morphologies with the characteristics known to yield high device performance could provide an effective form of solar energy harvesting that remains stable over time.The bicontinuous microemulsion (BμE) 3−5 is a well-known equilibrium morphology characterized by cocontinuous domains, high interfacial areas, and nanoscale domain dimensions. These characteristics make the BμE potentially suitable for use as an "ideal" device active layer in organic photovoltaic applications. In the context of polymeric systems, the BμE is often achieved by the addition of a diblock copolymer compatibilizer (AB) to a blend of two immiscible homopolymers (A and B). 4 Previous studies have demonstrated the rational design of BμEs using a variety of flexible polymeric materials. 6−8 Unfortunately, these f lexible polymer materials are typically inappropriate for use in OSC active layers. However, recent simulations by Kipp et al. demonstrated that diblock copolymer compatibilizers can also be used as an additive in semif lexible polymer/solvent blends to achieve BμE phases (the authors studied this system as a model for the conjugated polymer/PCBM system often used in OSCs). 9,10 Whether morphologies like those resulting from the simulations are accessible to the experiments remain...

We study the influence of block copolymer (BCP) compatibilizers on the domain and interfacial characteristics of the equilibrium morphological structures of semiflexible polymer/solvent blends. Our study is motivated by the question of whether block copolymer compatibilizers can be used to influence the phase separation morphologies resulting in conjugated polymer/fullerene blends. Toward this objective, we use a single chain in mean field Monte Carlo simulations for the phase behavior of semiflexible polymer/solvent blends and study the influence of BCP compatibilizers on the morphologies. Our results reveal a range of blend compositions and molecular chemistries that result in equilibrium structures with domain sizes on the order of 5-20 nm. To elucidate the morphological characteristics of these structures, we first present a series of ternary phase diagrams and then present results demonstrating that the blend composition, semiflexible chain rigidity, BCP composition, and component miscibility each provide unique handles to control the phase separation morphologies and interfacial characteristics in such blends.

In this letter, the authors describe both a growth method for self-aligning copper silicide (Cu3Si) nanobeams and their use as active catalysts for carbon nanotube (CNT) synthesis via chemical vapor deposition. In the unique geometry of these useful structures, CNT cantilevers are anchored firmly to the Cu3Si nanobeams. The resulting CNT-Cu3Si structures may improve accuracy and reliability of CNT applications in nanoelectromechanical systems.