Solvent-Free and Catalyst-Free Synthesis of Cross-Linkable Polyfumaramides via Topochemical Azide-Alkyne Cycloaddition Polymerization

Abstract

Unsaturated polymers are important materials having a lot of applications. Among polymers, polyamides possess a prime position due to their thermal and chemical stability. Herein, we report a simple, greener, catalyst-free, and solid-state synthesis of two unsaturated polyamides via a topochemical azidealkyne cycloaddition reaction. Two designed fumaramide monomers M1 and M2, functionalized with complementary azide and alkyne reactive motifs at the termini, reacted upon heating their crystalline powders and resulted in the formation of triazolyl-linked unsaturated polyfumaramides P1 and P2, respectively. We have characterized the reaction using various time-dependent techniques such as NMR, FTIR, PXRD, and DSC measurements. Interestingly, the monomer M1 resulted in 1,5-disubstituted triazole-linked unsaturated polyfumaramide (P1), whereas the monomer M2 polymerized into a polyfumaramide having both 1,4-disubstituted and 1,5-disubstituted triazole linkages (P2). Also, the trans-olefinic bond of both the fumaramide monomers was unaffected in the polymerization process and hence yielded unsaturated polymers having trans-olefin units in the repeating unit. Demonstrating the scope of postsynthetic modification, we have shown that unsaturation can be exploited for cross-linking via a light-induced [2 + 2] cycloaddition reaction. This first report on the solid-state synthesis of unsaturated polyfumaramides will be of great interest.

Micellar Mechanisms for Desymmetrization Reactions in Aqueous Media

“…These reactions were among the first examples of water-mediated desymmetrization reactions. Half-esters produced in these reactions are very versatile building blocks applied to the synthesis of pharmaceuticals, natural products, and polymers. − These reactions can produce the corresponding half-esters even in near-quantitative yields in many cases.…”

Recent progress in single-crystal structures of organic polymers

“…Besides controlling the crystallization process, topochemical polymerization has also been confirmed as a promising way to prepare single crystals of conjugated polymers. 3,25–49 Topochemical polymerization is a transformation process in the crystal state, where the critical factor is the suitable spatial arrangement of functional groups that are able to form new covalent bonds under the stimulation of light/heat/pressure. 17,25,50–52 Thus, minimizing the impact of newly formed covalent bonds on the structural arrangement while simultaneously maintaining the crystallinity (single crystals) is highly desirable but extremely challenging.…”

Highly Stretchable Fully Biomass Autonomic Self-Healing Polyamide Elastomers and Their Foam for Selective Oil Absorption

“…Solution polymerization based on acid chlorides/dimethyl esters results in greater toxic condensates and the raw materials utilized in this kind of process require additional synthetic steps and workup. Additionally, toxic solvents are required to remove the homogeneous catalyst after manufacturing [32]. Therefore, solvent-free melting polycondensation is one of the most extensively utilized synthetic methods for the production of commercial engineering plastics such as polyamides (PAs), polycarbonates (PCs), and polyesters (PEs) [33,34].…”