Self-assembling, macroscopically oriented, polymer filaments; a doubly nematic organogel.

Nanoscale phase separation and self-organisation in liquid crystals leads to the formation of remarkable hierarchical structures. There are several examples of heliconical nanofilament structures including in the nematic twist-bend (NTB) phase, the B4 phase and liquid crystal gels formed from the B4 phase. Both the formation of the polymer-like structures that permeate the soft-solids and their hierarchical structures are fascinating, not least because of the analogies that can be drawn with naturally-occurring structures. Here, we report a remarkably simple binary system formed from a non-symmetric BC molecule and the rod-like liquid crystal, 5CB. The pure bent-core system exhibits both nematic and dark conglomerate liquid crystal phases. At very low concentrations of the BC material (5-10%) this binary system spontaneously self-assembles into a soft solid formed from nanoscale filaments that are aligned by their nematic environment. Macroscopically, the soft solid shows behaviour that can be associated with both polymers and gels. Interestingly, the sub-micron scale structure of the filaments appears remarkably similar to some organised fibrous structures in nature (e.g. chitin, cellulose, insect cuticle, plant cell walls) something we attribute to self-assembly and self-organisation in an aligned liquid crystalline environment. The nanoscale structure of the filaments shows no features that can be associated with heliconical ordering down to length scales of tens of nanometers. However, the X-ray data suggest that a metastable rectangular columnar phase which is highly ordered in one dimension initially forms, changing to a hexagonal lattice on a timescale of tens of minutes.

A novel experimental approach to investigate radiolysis processes in liquid samples using collimated radiation sources.

Here is detailed a novel and low-cost experimental method for high-throughput automated fluid sample irradiation. The sample is delivered via syringe pump to a nozzle, where it is expressed in the form of a hanging droplet into the path of a beam of ionising radiation. The dose delivery is controlled by an upstream lead shutter, which allows the beam to reach the droplet for a user defined period of time. The droplet is then further expressed after irradiation until it falls into one well of a standard microplate. The entire system is automated and can be operated remotely using software designed in-house, allowing for use in environments deemed unsafe for the user (synchrotron beamlines, for example). Depending on the number of wells in the microplate, several droplets can be irradiated before any human interaction is necessary, and the user may choose up to 10 samples per microplate using an array of identical syringe pumps, the design of which is described here. The nozzles consistently produce droplets of 25.1 ± 0.5 µl.