The synthesis and characterization of five hydrogen-bonded ferroelectric liquid crystal complexes (HBFLCs) prepared from mesogenic p-n-alkoxy benzoic acids and non-mesogenic propionic/butyric acids with different chiral centres are reported. Complementary intermolecular hydrogen bonding is confirmed through IR study. HBFLCs are found to exhibit chiral nematic (N*), smectic C* (SmC*) and smectic G* (monotropic) phases in their cooling profiles during polarizing thermal microscopy and differential scanning calorimetry. Phase coexistence regions are observed above the IN* transition. The chiral nematic to smectic C* transition is found to be of first order. The temperature variation of spontaneous polarization exhibited by these HBFLC complexes in their SmC* phase is presented. The effect of non-covalent interaction imparted by the soft hydrogen bonding in these LC complexes on enhanced or induced thermal stability of tilted LC phases is discussed.

A series of intermolecular hydrogen bonding complexes, 2,2'-bipyridine: p- n-alkoxybenzoic acids (BP : nABA) was isolated from liquid crystalline p-n-alkoxybenzoic acids (nABA) (where n represents alkoxy carbon numbers, 3 to 10 and 12) and a non-mesogen, 2,2'-bipyridine (BP). The thermal and phase behaviour of these complexes was studied by thermal microscopy and differential scanning calorimetry (DSC). These studies revealed the induction of tilted smectic F and crystal G phases. The structural elucidation pertaining to the formation of intermolecular hydrogen bonding was carried out by a detailed IR spectral investigation. Comparative crystallization kinectic studies using DSC, performed on two representative compounds, showed different forms of the crystallization process. The magnitudes of the Avrami exponent n suggests two different mechanisms operate for individual members leading to sporadic three-dimensional growth. Nevertheless, an overall unique mechanism is predicted to operate at each crystallization temperature investigated, while the Avrami constant b shows a temperature dependence suggesting a strong influence of alkoxy terminal groups on the rates of nucleation.

A new series of mesomorphic complexes formed through intermolecular hydrogen bonding between p-n-alkoxybenzoic acids (where alkoxy denotes chains from propoxy- to decyloxy- and dodecyloxy-) and non-mesogenic p-hydroxybutyl benzoate, have been synthesized and characterized by thermal microscopy, differential scanning calorimetry, infrared spectroscopy (IR) and 1H NMR studies. A detailed IR spectral investigation in the solid state and in solution suggests that the acid and phenol groups are complementary to each other, each acting as both proton donor and proton acceptor. The results of comparative thermal analyses of both free p-n-alkoxybenzoic acids and H-bonded complexes exhibited an induced crystal smectic G phase in the complexes throughout the series, its thermal range increasing with alkoxy carbon number.

The usage of natural fibers is regarded as the most viable solution for controlling the consumption of synthetic materials. However, the low moisture resistance, stiffness and poor adhesion capabilities restrict their use in several advanced composite applications. Hence, different surface treatments are employed to improve the physical characteristics of natural materials. In this study, the effect of chemical treatments (sodium hydroxide, acetic acid, potassium permanganate and bromodecane) on the surface characteristics and the adhesion capabilities of Furcraea foetida (FF) fiber with epoxy material is evaluated. From the study, it is seen that the chemical treatment (CT) eliminates the O-H functional groups and enhances the hydrophobic characteristics in FF fiber. Furthermore, the CT removes the amorphous organic attachments and improves the crystallinity in the fiber. However, no substantial increase in the thermal stability of FF fiber was observed post chemical treatment. The microscopic analysis of chemically treated FF (CTFF) fiber shows the elimination of organic attachments and developed neat uniform surface structure. The NaOH-treated FF fiber exhibited maximum tensile strength (σ_t: 241.75 MPa). Whereas the acetic acid-treated FF fiber showed maximum tensile modulus (σ_m: 6.9 GPa) and interfacial shear strength (IFSS: 0.06 MPa) compared to CTFF and untreated FF fiber (UTFF).