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Self-assembly behaviors of a series of hydrophobic side-chain liquid crystalline (LC) polyacetylenes, namely, poly(5-(4‘-alkoxy-4-biphenylyl)carbonyloxy-1-pentyne)s P-3,m(m5, 7, 9), were studied in dilute solutions. The assembly was induced by tuning the solvent property to be selective for the alkyl tails on the side chains, with the processes characterized by turbidity, dynamic light scattering, 1H NMR, and excitation fluorescence anisotropy measurements. The morphology and structure of the P-3,maggregates formed in the solutions were investigated using atomic force microscopy and wide-angle X-ray diffraction. The experimental results indicate that the P-3,mpolymers can form monolayer lamellae in selective solvents. In the lamella, the P-3,mmolecules are sheetlike and pack parallel to each other with their backbones located in the lamellar center and their alkyl tails covering the top and bottom lamellar surfaces. The lamellar thickness is largely determined by the width of the molecular sheet. When the solvent becomes selective for the tails, the P-3,mchains may undergo shape stiffening to become more sheetlike. [ABSTRACT FROM AUTHOR]

Dipole coupled nanomagnets controlled by the static Zeeman field can form various magnetic logic interconnects. However, the corner wire interconnect is often unreliable and error-prone at room temperature. In this study, we address this problem by making it into a reliable type with trapezoid-shaped nanomagnets, the shape anisotropy of which helps to offer the robustness. The building method of the proposed corner wire interconnect is discussed, and both its static and dynamic magnetization properties are investigated. Static micromagnetic simulation demonstrates that it can work correctly and reliably. Dynamic response results are reached by imposing an ac microwave field on the proposed corner wire. It is found that strong ferromagnetic resonance absorption appears at a low frequency. With the help of a very small ac field with the peak resonance frequency, the required static Zeeman field to switch the corner wire is significantly decreased by ∼21 mT. This novel interconnect would pave the way for the realization of reliable and low power nanomagnetic logic circuits. [ABSTRACT FROM AUTHOR]

Phase structures and transitionsof a series of biphenyl containingside-chain liquid crystalline polyacetylenes (SCLCPAs) with differentlength of spacer and alkyl tail, poly((m + 2)-{[(4′-alkyloxy-4-biphenylyl)carbonyl]oxy}-1-yne)[P-m,7 (m= 4, 5, 8), P-m,5 (m= 9), P-m,5L(m= 3, 9), mis the numberof methylene units in the spacer], were studied by differential scanningcalorimeter, polarized light microscopy, one- and two-dimensionalwide-angle X-ray diffraction. It is revealed that phase structuresof the samples are strongly dependent on the lengths of spacer andalkyl tail. The samples with short spacer (m≤4) render the molecular shape of sheet-like due to the strong couplingbetween the backbone and the biphenyl groups on side-chains. Theyform highly ordered smectic phase with an additional ordering on thesubnanometer scale (SmXo) at low temperatures. For m> 5, P-m,7 exhibits the low-temperaturephase of smectic B (SmB), while P-9,5 and P-9,5Lform smecticE (SmE). As the long spacers adopt more gaucheconformationsto satisfy the ordered packing of biphenyl groups, the coupling ofmain- and side-chain is relieved. Among the samples studied, P-5,7is unique, which can retain the sheet-like shape but form the SmBstructure based on a fully interdigitated packing manner. Therefore,the spacer length of m= 5 sets the boundary betweencoupling and decoupling of the backbone and side-chains. Phase transitionsequences of the SCLCPAs studied are also found to be influenced clearlyby varying the spacer and tail lengths. [ABSTRACT FROM AUTHOR]