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The formation of lyotropic solutions in water has yet to be reported for polyaramides. In this work, we investigate the synthesis and properties of a water-soluble polyaramid via the inclusion of a sulfonated monomer in the backbone of the polymer chain. Using sulfonated terephthalic acid (sTA) together with a diamine and a diisocyanate enables us to produce a lyotropic water-soluble polyaramid poly(p-phenylene−sulfoterephthalamide). Two different synthetic routes are presented:  (1) the reaction between sTA and p-phenylene diisocyanate (PPDI) and (2) the reaction of activated sTA using triphenyl phosphite and p-phenylenediamine (PPD). Polymers with various molar masses up to 15 000 g mol^-1 using both methods have been obtained. We have examined the optimal reaction conditions for the synthesis of these polymers, in particular the effect of reaction temperature, concentration of monomers and reactants, type of counterions, and solvents. The polymers obtained are mostly soluble in water, up to high concentration (10 wt % without an alkali counterion on the sulfonic acid group), and surprisingly lyotropic nematic behavior has been observed independent of the molar mass of the polymer. The phase diagram of these materials in water has been investigated, and the lyotropic phase has been characterized using optical polarized microscopy.

Investigation of glass transition dynamics in polyolefins by broadband dielectric spectroscopy (DRS) is facilitated by the addition of a novel dielectric probe, (4,4‘-(N,N-dibutylamino)-(E)-nitrostilbene (DBANS), which introduces dipoles and made the polymers dielectrically active. For probe concentrations between 0.1% and 1.0% the dielectric strength Δε associated with the dynamic glass transition increases proportionally to the probe concentration. This result indicates that the probe exhibits no intramolecular relaxations, and the probe rotational diffusion effectively senses the “microviscosity” of the probe environment on the length scale of the segmental dynamics. Temperature-dependent fluorescence spectroscopy on doped polymers shows no changes in fluorescence wavelength around the glass transition temperature. Crystallization and melting of the polyolefin matrix results in an increase or decrease of the probe concentration in the amorphous phase, which was clearly detected by real-time fluorescence because the probe emission is sensitive to the probe content, particularly at higher probe concentrations.

Free volume relaxation of polycarbonate (PC) as a function of aging time was investigated by means of positron annihilation lifetime spectroscopy at three different temperatures below the PC glass transition temperature. A clear decrease of the intensity of orthopositronium (o-Ps) was observed, while the o-Ps lifetime remained substantially unchanged. This was attributed to a decrease in the number of cavities in the system. The process was successfully modeled according to the Struik model, which describes a relaxation time dependent on both the temperature and the distance from equilibrium.

We have prepared a new discotic nematogen, bearing one functional tail and five methoxy substituents. The corresponding side chain polymers, prepared via a polymer analogous esterification reaction, exhibited ND phases from 50 °C until degradation above 200 °C. Addition of equimolar amounts of various trinitrofluorenone-based acceptors to the mesogen resulted in the formation of charge transfer complexes with a variety in liquid crystalline properties. Depending on the acceptor, different columnar and nematic phases are induced, including the recently discovered nematic lateral phase. The liquid crystalline properties were investigated with differential scanning calorimetry, optical polarizing microscopy, and extensive X-ray diffraction (XRD).

Charge-transfer complexes of a disk-shaped electron-rich donor, based on pentakis(phenylethynyl)phenol and a series of electron-deficient acceptors, based on 2,4,7-trinitro-9-fluorenone have been prepared. Specific interactions resulted in supramolecular assemblies that exhibited various mesophases, although none of the pure materials showed liquid crystalline properties. Complexes of the low molar mass donor with a weak, intermediate, and a strong acceptor exhibited ND, NCol, and Colh phases, respectively, as well as strong increases in the melting and clearing temperatures. Complexes with the corresponding macromolecular donor showed the nematic lateral (NL) phase. In addition, suppression of crystallization led to mesophases stable over a wide temperature range. The use of a polymer bound mesogens and charge-transfer complexing are effective tools to induce a wide variety of unusual mesophases, starting from a limited number of materials.

A novel liquid crystalline polyacrylate, exhibiting a nematic columnar and a nematic discotic phase, the latter not found in any polymer previously, has been synthesized using a polymer analogous reaction, substituting the discotic mesogens on a reactive polymer. The highly flexible concept of the polymer analogous reaction enables us to introduce structural variations and to create and control molecular architectures. The mesophases of polymer 1, bearing the pentakis(methylphenylethynyl)benzene mesogen via a flexible undecanoxy spacer, as well as its low molar weight homologue 2, were fully characterized by optical polarizing microscopy, differential scanning calorimetry and powder X-ray diffraction. The thermal behavior of both compounds is qualitatively similar. Both materials exhibit a nematic discotic phase (ND) at higher temperatures, which is unique for the polymer, as this phase has only been observed in low molar mass materials so far. At lower temperatures 2 crystallizes, whereas 1 undergoes a transition into the nematic columnar phase (Ncol).

Side-chain liquid-crystalline copolymers (SCLCPs) were synthesized from the alternating copolymerization of maleic anhydride with mesogenic 1-olefins. These SCLCPs showed high glass transition temperatures and highly ordered smectic mesophases. The mesophase width increased with spacer length. The terminal alkyl group length determined the degree of order in the hexatic mesophase that was present just above the glass transition temperature. A terminal methoxy group induced a hexatic smectic B mesophase, intermediate terminal alkyl groups induced a smectic E mesophase, and long terminal alkyl groups induced a crystal smectic B mesophase. If the spacer was shorter than the terminal alkyl group, an interdigitated smectic A mesophase was found in which the terminal alkyl groups overlap. A strong correlation was found between the glass transition temperature and the temperature at which the hexagonal or orthorhombic ordered mesophase disappears. Introduction of an ester linkage between the spacer and biphenyl mesogen or replacing the terminal alkoxy group by a cyano terminal group induced a lowering of transition temperatures and a lower degree of order in the mesophase.