Synthesis and Rheological Behavior of Supramolecular Ionic Networks Based on Citric Acid and Aliphatic Diamines

Abstract

Novel supramolecular ionic networks were obtained by reacting citric acid and aliphatic diamines. A proton transfer reaction takes place between the carboxylic acid of citric acid and the amine group leading to the corresponding ionic carboxylate and quaternary ammonium groups. By this method, a series of supramolecular ionic networks were obtained due to the multiple ionic interactions between the corresponding citrate and diammonium molecules as observed by FTIR spectroscopy. Rheological analysis of the ionic networks was carried out considering frequency and temperature sweeps in small-amplitude oscillatory flow and viscous measurements in continuous flow. At low temperatures and/or high frequencies the ionic interactions brought about an elastic network or gel which vanished at high temperatures and/or low frequencies. The viscoelastic behavior was governed by a single relaxation time and a very high plateau modulus, G p = 5 × 106 Pa. The relaxation time showed an Arrhenius-like dependency with temperature, leading to draw diagrams of the physical states for each sample. The obtained supramolecular ionic networks based on different aliphatic diamine molecules did not show differences in their respective solid and liquid states. However, the frequency-dependent network–liquid transition temperature, T nl, varied with the chemical nature of the diamines. The higher T nl (45 °C) was found for the system that contains 1,3-diaminopropane which is attributed to stronger ionic bonds involving primary amines, with respect to ionic bonds with tertiary amines (between −1 and 32 °C). Comparing ionic networks obtained from different tertiary diamines, such as tetramethyl-1,3-propanediamine and tetraethyl-1,3-propanediamine, the lower T nl was observed in the latter, ascribed to a higher mobility of the aliphatic pendant groups.

Effect of the Dianhydride/Branched Diamine Ratio on the Architecture and Room Temperature Healing Behavior of Polyetherimides

“…As seen in Table II, the plateau moduli (G N ) for these polyimides are of the order of 10 5 -10 6 Pa. Such values are in agreement with similar values obtained for supramolecular self-healing polymers based on metal ionic interactions in rubbery poly(n-butyl acrylate) ionomers (39), hydrogen bonding end groups in poly(isobutylene) (40) and ionic networks reacting neutralized citric acid and aliphatic diamines (41). When the relation of rubber elasticity, G N = ρRT/M e , is applied to these polymers and the molecular weight between effective interactions M e is calculated, values of M e between 2000 and 4000 g/mol are obtained (Table II).…”

Spontaneous formation of polylactide stereocomplex microspheres containing metal ions

“…In the IR spectrum of the PLA stereocomplex obtained in the presence of CaO (Fig. ) the signal corresponding to carboxylate anion at 1570 − 1675 cm –1 is visible in the vicinity of a large signal corresponding to carbonyl groups at 1750 cm –1 , both from ester groups in PLA repeating units (and possibly from non‐ionized −COOH groups) . Model studies with only one PLA stereoisomer (PLLA‐(COOH) 1 ) and with CaO added in different amounts additionally supported this result.…”

Intelligent rubber with tailored properties for self-healing and shape memory

“…carboxylates, 3 sulfates). 4,[53][54][55] In recent years, this type of reversible non-covalent interaction has been used to construct supramolecular systems. the classical acid-base reaction.…”

“…49,50 These bonds are usually formed by mixing acid and base, i.e. [53][54][55][56][57][58][59] Pioneering works by Matsushita and coworkers described a simple preparation of supramolecular polymer by mixing carboxy-terminated telechelic polymers (PEA-(COOH) 2 , PDMS-COOH) with PEI, a multi-amino polymer. 51,52 Besides, amidinium carboxylate or sulfonate ion pairs generally formed between organic cations and anions are also defined as ionic interactions in some reports.…”