Three-dimensional blueprinting of molecular patterns in liquid crystalline polymers.

Exploiting the interplay of anisotropic diamagnetic susceptibility of liquid crystalline monomers and site selective photopolymerization enables the fabrication of 3D freeforms with highly refined microstructures. Utilizing chain transfer agents in the mesogenic inks presents a pathway for broadly tuning the mechanical properties of liquid crystalline polymers and their response to stimuli. In particular, the combination of 1,4-benzenedimethanethiol and tetrabromomethane is shown to enable voxelated blueprinting of molecular order, while allowing for a modulation of the crosslink density and the mechanical properties. The formulation of these monomers allows for the resolution of the voxels to approach the limits set by the coherence lengths defined by the anchoring from surfaces. These compositions demonstrate the expected thermotropic responses while allowing for their functionalization with photochromic switches to elicit photomechanical responses. Actuation strains are shown to outstrip that accomplished with prior systems that did not access chain transfer agents to modulate the structure of the macromolecular network. Test cases of this system are shown to create freeform actuators that exploit the refined director patterns during high-resolution printing. These include topological defects, hierarchically-structured light responsive grippers, and biomimetic flyers whose flight dynamics can be actively modulated via irradiation with light.

5,7-Bis(1-benzothio-phen-2-yl)-2,3-dihydro-thieno[3,4-b][1,4]dioxine.

In the title compound, C(22)H(14)O(2)S(3), the dioxane ring is disordered over two sites [site occupancies = 0.623 (3) and 0.377 (3)]; both components adopt half-chair conformations. The two benzothio-phene ring systems are asymmetrically twisted away from the attached thio-phene ring [dihedral angles = 20.57 (3) and 6.70 (3)°] and are oriented at an angle of 26.83 (3)°. No significant hydrogen bonding or π-π inter-actions are observed in the crystal structure.

Naphthalene-2,3-diylbis[(2-thien-yl)methanone].

The asymmetric unit of the title compound, C(20)H(12)O(2)S(2), contains two crystallographically independent mol-ecules which differ in the orientations of thienylmethanone units with respect to the naphthalene ring system [dihedral angles of 65.30 (11) and 50.94 (11)° in one molecule, 41.94 (12) and 69.61 (13)° in the other]. The crystal structure is stabilized by C-H⋯O and C-H⋯π inter-actions.