Overcoming the Low Driving Force in Forming Depolymerizable Polymers through Monomer Isomerization

Abstract

While depolymerizable polymers have been intensely pursued as ap otential solution to address the challenges in polymer sustainability,m ost depolymerization systems are characterized by alow driving force in polymerization, which poses difficulties for accessing diverse functionalities and architectures of polymers.H ere,w ea ddress this challenge by using ac yclooctene-based depolymerization system, in which the cis-to-trans alkene isomerization significantly increases the ring strain energy to enable living ring-opening metathesis polymerization at monomer concentrations ! 0.025 M. An additional trans-cyclobutane fused at the 5,6-position of the cyclooctene reduces the ring strain energy of cyclooctene, enabling the corresponding polymers to depolymerizeinto the cis-cyclooctene monomers.T he use of excess triphenylphosphine was found to be essential to suppress secondary metathesis and depolymerization. The high-driving-force living polymerization of the trans-cyclobutane fused trans-cyclooctene system holds promise for developing chemically recyclable polymers of awide variety of polymer architectures.

Chemically recyclable polymer materials: polymerization and depolymerization cycles

“…Sequentially, Wang also found that the cis-to-trans alkene isomerization of these monomers significantly increased the ring strain energy, enabling ring-opening metathesis polymerization to occur at a relatively low monomer concentration. 221 More recently, Wang has also discussed the structure-polymerization thermodynamics relationship of fused-ring cyclooctenes and extended the polymerizationdepolymerization cycle to a series of new monomers, such as M6 and M7. 222…”

Recent Advances in Monomer Design for Recyclable Polymers

“…通过环辛二烯与马来酸酐发生 2＋2 环加成反 应构建反式环辛烯并四元环结构, 然后发生转化得到不 同功能单体, 其可以在 G2 的催化下顺利发生聚合反应 得到 M n ＞100 kg/mol 的聚合物, 但是分子量分布很宽 (Ɖ＞1.5). 随后研究发现, 通过光照使顺式烯烃异构化 为反式烯烃(图 23), 而反式烯烃环张力增加可以在该聚 合条件下实现活性聚合 [177] . 机械性能测试表明, 改变 四元环上取代基的结构, 聚合物为弹性体或者聚苯乙烯 类似机械性能.…”

Depolymerizable semi-fluorinated polymers for sustainable functional materials

“…Another unique feature of this system is that the driving force for polymerization can be elevated by isomerizing the cis -cyclooctene to its trans form, allowing the polymerization to be conducted in dilute monomer concentrations (≥25 mM). 32 Herein, we leverage the versatility of the t CBCO system and report chemically recyclable semi-fluorinated polymers (Fig. 1b, P1–P3 ).…”