Redesigned Hybrid Nylons with Optical Clarity and Chemical Recyclability

Abstract

Aliphatic polyamides, or nylons, are typically highly crystalline and thermally robust polymers used in high-performance applications. Nylon 6, a high-ceiling-temperature (HCT) polyamide from ε-caprolactam, lacks expedient chemical recyclability, while low-ceiling temperature (LCT) nylon 4 from pyrrolidone exhibits complete chemical recyclability, but it is thermally unstable and not melt-processable. Here, we introduce a hybrid nylon, nylon 4/6, based on a bicyclic lactam composed of both HCT ε-caprolactam and LCT pyrrolidone motifs in a hybridized offspring structure. Hybrid nylon 4/6 overcomes trade-offs in (de)­polymerizability and performance properties of the parent nylons, exhibiting both excellent polymerization and facile depolymerization characteristics. This stereoregular polyamide forms nanocrystalline domains, allowing optical clarity and high thermal stability, however, without displaying a melting transition before decomposition. Of a series of statistical copolymers comprising nylon 4/6 and nylon 4, a 50/50 copolymer achieves the greatest synergy in both reactivity and polymer properties of each homopolymer, offering an amorphous nylon with favorable properties, including optical clarity, a high glass transition temperature, melt processability, and full chemical recyclability.

Beyond nylon 6: polyamides via ring opening polymerization of designer lactam monomers for biomedical applications

“…Moreover, few nylon 4 and nylon 5 polymers are synthesized or studied due to low thermal stability and a lack of reproducible polymerization techniques, respectively. Incorporating C-2 and C-4 functionalizations on the polymer backbone, similar to the recent report by Cywar et al , 130 as well as N-terminal and C-terminal functionlizations will improve thermal stability for nylon 4 polymers. 131 Therefore, we encourage the scientific community to explore the synthesis of thermally stable, functionalized nylon 4 polymers.…”

“…Incorporation of biodegradable nylon 4 and nylon 2 monomers into higher order nylons is another strategy explored to prepare new classes of nylons with tuneable biodegradability. 142 Finally, the successful transition of several of these nylon polymers to in vitro and in vivo studies as devices, therapeutic agents, or macromolecular carriers for drug delivery bodes well for their continued investigation. We encourage the scientific community to explore the utilization of amphiphilic nylon polymers for delivery of small molecules as well as large biomacromolecules such as enzymes, chemokines, RNA, or DNA.…”

“…Incorporation of biodegradable nylon 4 and nylon 2 monomers into higher order nylons is another strategy explored to prepare new classes of nylons with tuneable biodegradability. 142…”

Recent Advances in Monomer Design for Recyclable Polymers

“…所得不同结构的聚合 物均可发生解聚反应回到单体 BiL = , 实现了从一种单体 到两种不同类型聚合物的闭环回收过程. 最近, Chen 等 [48] 又将该策略应用于环内酰胺单体的设计中, 七元 环内酰胺具有高的 T c 容易发生聚合反应, 但是其降解选 择性较差, 相反五元环内酰胺回收性能很好, 但是聚合 物稳定性较差. Chen 等设计的杂化 5/7-LM 可以很好地 平衡聚合物力学性能和降解性能.…”

Dithioacetal Polymers Capable of Chemical Recycling to Macrocyclic Monomers and Formation of Vitrimers

“…This reversible ring-chain recycling process has recently been demonstrated for various cyclic monomers such as acetals, 9 carbonates, [10][11][12][13] alkenes, [14][15][16][17][18] lactones, [19][20][21][22][23][24][25] thiolactones, [26][27][28][29] and lactams. 30 Such polymerizations are typically driven by the relief of ring strain of small cyclic monomers, leading to a favorable enthalpy change (ΔHp < 0) that overcomes the unfavorable entropy (ΔSp < 0) due to the loss of translational entropy. Highly efficient depolymerization and repolymerization can be achieved within desirable temperature ranges by modulating the ring-strain of the cyclic monomers via varying the ring size, substituents, and geometry.…”