At the microscopic scale, carbon nanotubes (CNTs) combine impressive tensile strength and electrical conductivity; however, their macroscopic counterparts have not met expectations. The reasons are variously attributed to inherent CNT sample properties (diameter and helicity polydispersity, high defect density, insufficient length) and manufacturing shortcomings (inadequate ordering and packing), which can lead to poor transmission of stress and current. To efficiently investigate the disparity between microscopic and macroscopic properties, a new method is introduced for processing microgram quantities of CNTs into highly oriented and well-packed fibers. CNTs are dissolved into chlorosulfonic acid and processed into aligned films; each film can be peeled and twisted into multiple discrete fibers. Fibers fabricated by this method and solution-spinning are directly compared to determine the impact of alignment, twist, packing density, and length. Surprisingly, these discrete fibers can be twice as strong as their solution-spun counterparts despite a lower degree of alignment. Strength appears to be more sensitive to internal twist and packing density, while fiber conductivity is essentially equivalent among the two sets of samples. Importantly, this rapid fiber manufacturing method uses three orders of magnitude less material than solution spinning, expanding the experimental parameter space and enabling the exploration of unique CNT sources.

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Boron nitride nanotubes (BNNTs) are novel material building blocks with useful thermal, electronic, and optical properties; their stable dispersion in water would enable fundamental studies as well as novel applications. Here we address the dispersion of BNNTs in aqueous solution using surfactants with varying properties.

Block copolymers (BCPs) self-assembled into 3D network phases are promising for designing useful materials with multiple properties that rely on domain continuity. However, access to potential applications has been limited because network formation with linear BCPs tends to occur only over narrow compositional windows. Another constraint is slow self-assembly kinetics at higher molecular weights, which limits the network unit cell dimensions and the resulting material properties. Architecturally asymmetric, linear-bottlebrush BCPs have previously been demonstrated to promote self-assembly into complex micellar phases. The architectural asymmetry has been demonstrated to induce favorable curvature toward the linear block. However, linear-bottlebrush copolymer phase behavior and self-assembly into network phases have not been systematically studied. Here, we map the phase behavior of eight sets of diblock polymers with a linear-bottlebrush architecture in the expected vicinity of the double-gyroid phase. We demonstrate the effects of architectural asymmetry and the linear block cohesive energy density on self-assembly into double-gyroid, lamellar, and hexagonal phases. Through a combination of molecular and structural characterization techniques, we demonstrate that the shape of the polymer and the identity of the linear block provide significant control over the molecular factors that dictate network formation.