Covalent Adaptable Polymethacrylate Networks by Hydrazide Crosslinking Via Isosorbide Levulinate Side Groups

Abstract

Reversible crosslinking offers an attractive strategy to modify and improve the properties of polymer materials while concurrently enabling a pathway for chemical recycling. This can, for example, be achieved by incorporating a ketone functionality into the polymer structure to enable post-polymerization crosslinking with dihydrazides. The resulting covalent adaptable network contains acylhydrazone bonds cleavable under acidic conditions, thereby providing reversibility. In the present work, we regioselectively prepare a novel isosorbide monomethacrylate with a pendant levulinoyl group via a two-step biocatalytic synthesis. Subsequently, a series of copolymers with different contents of the levulinic isosorbide monomer and methyl methacrylate are prepared by radical polymerization. Using dihydrazides, these linear copolymers are then crosslinked via reaction with the ketone groups in the levulinic side chains. Compared to the linear prepolymers, the crosslinked networks exhibit enhanced glass transition temperatures and thermal stability, up to 170 and 286 °C, respectively. Moreover, the dynamic covalent acylhydrazone bonds are efficiently and selectively cleaved under acidic conditions to retrieve the linear polymethacrylates. We next show that recovered polymers can again be crosslinked with adipic dihydrazide, thus demonstrating the circularity of the materials. Consequently, we envision that these novel levulinic isosorbide-based dynamic polymethacrylate networks have great potential in the field of recyclable and reusable biobased thermoset polymers.

Mechanism Study on Synthesis of Biobased Polycarbonate from Diphenyl Carbonate and Isosorbide with Metal-Free Catalysts by Identifying Reactivity of endo-OH and exo-OH

“…The synthesis of polymers and materials derived from biobased monomers instead of petroleum-based compounds aligns with the principles of green and sustainable development. − Isosorbide (ISB), a renewable resource derived from glucose, has garnered substantial attraction as a viable alternative to petroleum-based monomers. − Notably, the ISB molecule features two asymmetric hydroxyl groups: an exo -hydroxyl group ( exo -OH) and an endo -hydroxyl group ( endo -OH), the latter forming an intermolecular hydrogen bond with the oxygen atom on the adjacent furan ring. , …”

Semi-Crystalline and Amorphous Polyesters Derived from Biobased Tri-Aromatic Dicarboxylates and Containing Cleavable Acylhydrazone Units for Short-Loop Chemical Recycling

“…Compared to imines, acylhydrazone bonds possess higher hydrothermal stability but can be readily cleaved by acids, making them more suitable for practical applications. , Acylhydrazone bonds can be formed in a reaction of an aldehyde or a ketone with a hydrazide . Previously, reactions between the ketone group of the levulinic acid and adipic acid dihydrazide have been used to prepare linear and cross-linked polymers for coatings, drug delivery systems, and thermoset applications. − …”

Digital Light Processing 3D Printing of Isosorbide- and Vanillin-Based Ester and Ester–Imine Thermosets: Structure–Property Recyclability Relationships

“…Among the dynamic covalent bonds, imine functions have been demonstrated to favor the reprocessing and chemical degradation of the thermosets without the need for a catalyst. − The reprocessing of imine-based thermosets can take place by exploiting the metathesis pathway, an associative mechanism based on imine exchange. , Chemical degradation can occur according to a dissociative mechanism in a slightly acidic aqueous solution, with the consequent reformation of the aldehyde and amine functions, or in the presence of an excess of amines by exploiting the transimination pathway, an associative mechanism intended as an exchange between the imine group and amino functions forming a new imine and a new amine …”