Thermotropic Polyesters from 2,5-Furandicarboxylic Acid and Vanillic Acid: Synthesis, Thermal Properties, Melt Behavior, and Mechanical Performance

Abstract

In this work, we address the synthesis of novel aromatic−aliphatic biobased polyesters showing thermotropic behavior in the melt. Successful incorporation of different biobased monomers such as 2,5-furandicarboxylic acid (2,5-FDCA), suberic acid (SuA), and vanillic acid (VA) in thermotropic liquid crystalline polymers (TLCPs) is made possible by performing synthesis at low temperatures. The chemical structures, molecular weights, phase transitions, thermal behavior, and mechanical performance of the synthesized polymers are studied using polarization optical microscopy, WAXD, DSC, TGA, DMTA, solidstate NMR spectroscopy, rheology, and tensile tests. It is shown that the incorporation of the rigid, aromatic 2,5-FDCA moiety enhances the formation of blocky copolymers, whereas the VA moiety tends to decrease the block formation. However, when combined, nonblocky TLCPs containing 2,5-FDCA and VA with high aromatic content can be obtained. These materials show a low temperature transition from the crystalline to the nematic phase, and stable nematic phases up to 300 °C and higher. Furthermore, in such polymers, the 2,5-FDCA and VA moieties require more thermal energy to become mobile compared to the phenyl rings in hydroxybenzoic acid, hydroquinone, and 4,4′-biphenol. Mechanical analysis shows that the performance of these polymers is correlated to their crystallinity. Surprisingly, a higher crystallinity results in ductile behavior, whereas a lower crystallinity results in a higher modulus, a higher stress at break, and a lower strain at break.

Biobased polyesters and other polymers from 2,5-furandicarboxylic acid: a tribute to furan excellency

“…They have been tailored by means of different aliphatic monomers, including both those with linear carbon chain (that can span from C2 to C8), or instead, those with more rigid cyclic structure (typically 1,4:3,6dianhydrohexitols). Entirely aromatic polyesters, the furanic -aromatic polyesters, were also pursued, 9,10,32,33,[45][46][47][48][49][50] essentially aiming to prepare novel materials with enhanced thermal and mechanical properties (e.g. the glass transition could reach values as high as 109), 45 and/or liquid crystalline character.…”

Processing and performance of aromatic-aliphatic thermotropic polyesters based on vanillic acid

“…The monomers were loaded into a 500 mL three-neck round bottom flask fitted with a mechanical stirrer, together with 50e100 mg of Zn(AcO) 2 and the temperature was gradually increased to 260 C. Acetic acid was distilled off and reduced pressure was applied to the system for eight to twelve hours after roughly 90% of the expected acetic acid was collected. Details regarding the polymerization procedure are reported in a previous publication [15].…”

“…Similar to the T g , the transition from crystal to the nematic phase (T m ) of these polymers increases slightly with increasing molecular weights. It should be noted that none of the polymers IeIII exhibit a nematic to isotropic transition (NeI) upon heating, while heating in hot-stage polarization optical microscopy [15].…”

“…1) [14,15]. In these publications we demonstrated that the synthesis of high molecular weight copolymers containing small amounts of vanillic acid could be performed at low temperatures from the melt, generally yielding polymers with melting temperatures close to or below 200 C. Furthermore, the presence of vanillic acid is known to (a) improve the monomer sequence distribution, (b) increase the stability of the thermotropic melt, (c) decrease the polymer melting temperature, and (d) improve the spinnability of thermotropic polyesters [15e18].…”

Anti-hydrolysis performance of cured coating films of acrylic polyols with pendant poly(lactic acid)s

“…Carbon-neutral material is a material which does not affect the change in carbon dioxide amount emitted and absorbed in the materials' cycle. In particular, recent studies on bio-based materials, such as poly(lactic acid)s (PLA), poly(butylene succinate)s (PBS), denaturated starch, and soybean polyols, are to be paid much attention [9][10][11][12][13][14][15][16]. In automotive coatings production, many petroleum derived materials, like acrylic resins and polyurethane resins, are currently employed in much amount, and hence, we are aiming at the mitigation of global environment problems through developing the bio-based coatings from bio-based materials.…”