Influence of Chemical Structure on Processing and Thermotropic Properties of Poly(siloxane-azomethine)s

Abstract

A disiloxane dialdehyde was obtained from bis (chloromethyl)disiloxane and p-hydroxybenzal-dehyde and it was used in an equilibration (redistribution) reaction to synthesize an oligomeric dialdehyde. By solution polycondensation, starting from bis(formyl-p-phenoxymethyl)tetramethyldisiloxane and different organic diamines, poly(azomethine)s were obtained. In the case of aromatic diamines with high rigidity, which gave insoluble polymers, different approaches were tested in order to improve the solubility: the use of the dialdehyde having longer siloxane chain, or of a siloxane diamine in a copoly-condensation reaction. The polymers’ structures were confirmed by IR and 1H NMR spectroscopy and by elemental analysis. The structure-properties relationship was studied in terms of solubility, thermal and thermotropic behavior. Most of the obtained poly(azomethine)s has mesomorphic properties, which were studied by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction. The influence of aromatic diamines’ chemical structure on the processability of the siloxane-organic poly(azomethine)s was emphasized.

Synthesis, physicochemical studies and potential applications of high-molecular-weight ferrocene-based poly(azomethine)ester and its soluble terpolymers

“…The H-bonding present in the poly(azomethine) ester that had azomethine beside ester linkage gave stability to the chain. The TGA curves revealed a multistage process as reported earlier [24] which probably included pyrolytic cleavage of the (azomethine) ester, Fig. 6(a).…”

Kinetics of the Isotropic‐Ordered Phase Transition in Binary Mixtures of Mesogenic Monomers and Polymers

“…Details of the siloxane intermediate synthesis and generalized procedure of the polyazomethines production are given in Ref. (17). Another method of the LC polymer obtaining is described in Ref.…”

An overview of LC polyazomethines with aliphatic–aromatic moieties: Thermal, optical, electrical and photovoltaic properties

“…A few scientists investigated the LC properties of poly(siloxane-azomethine)s obtained from dialdehydes with two or six siloxane units and various diamines ( Fig. 1, structure XII) [34][35][36][37]. These polymers exhibited smectic or nematic phases (e.g., Tg [34][35][36][37].…”

“…Siloxane linkages are introduced to polymer structures due to their ability to lower the transition temperatures and enhance solubility and high gas permeability. Moreover, the siloxane units reduce the crystallinity without destroying the liquid crystalline nature of the polymers [33][34][35][36][37]. A few scientists investigated the LC properties of poly(siloxane-azomethine)s obtained from dialdehydes with two or six siloxane units and various diamines ( Fig.…”