Probing the Solubility of Imine-Based Covalent Adaptable Networks

Abstract

Covalent adaptable networks (CANs) are polymer materials that are covalently cross-linked via dynamic covalent bonds. The cross-linked polymer network is generally expected to be insoluble, as is seen for traditional thermosets. However, in recent years, it has become apparent that�under certain conditions�both dissociative and associative CANs can be dissolved in a good solvent. For some applications (e.g., those that require long-term (chemical) stability), the solubility of CANs can be problematic. However, many forget that (selective) solubility of CANs can also be applied advantageously, for example, in recycling or modification of the materials. In this work, we provide results and insights related to the tunable solubility of iminebased CANs. We observed that selected CANs could be fully dissolved in a good solvent without observing dissociation of imines. Only in an acidic environment (partial) dissociation of imines was observed, which could be reverted to the associated state by addition of a base. By adjusting the network composition, we were able to either facilitate or hamper solubility as well as control the size of the dissolved particles. DLS showed that the size of dissolved polymer particles decreased at lower concentrations. Similarly, decreasing cross-linking density resulted in smaller particles. Last, we showed that we could use the solubility of the CANs as a means for chemical recycling and postpolymerization modification. The combination of our studies with existing literature provides a better understanding of the solubility of CANs and their applications as recyclable thermosets.

Tunable Waterborne Aspartic Acid-Based Covalent Adaptable Networks with Internal Catalysis and Incorporation in Bioinspired Nanocomposites

“…15% for A3 3 EG 6 S 1 –C1. These results further indicate the cross-linked nature of the networks as well as resilience against hydrolysis of the potentially dynamic ester bonds (internal catalysts) in H 2 O, especially considering how, unlike thermosets, CANs can sometimes dissolve in good solvents. , Conditioning the CANs at 50% relative humidity (RH), followed by measurement of the water content, reveals their water uptake (Table S2). The data indicate a trend: CANs with more tertiary amines contain more water (A3 7 EG 2 S 1 –C1 > A3 5 EG 4 S 1 –C1 > A3 5 EG 4 S 1 –C3 > A3 3 EG 6 S 1 –C1 > A3 5 EG 4 S 1 –C2).…”