Aldehyde End‐Capped Degradable Polyethylenes From Hydrogen‐Controlled Ethylene/CO Copolymerization

To access degradable polyolefin plastic, non‐alternating copolymerization of ethylene (E) and carbon monoxide (CO) for producing polyethylene (PE) with in‐chain ketones is particularly appealing; however, it still presents significant challenges such as molecular weight modulation (hydrogen response) and chain endgroup control (functional terminal). In this study, we achieved hydrogen‐controlled E/CO non‐alternating copolymerization using late transition metal catalysts. This process results in linear PEs containing the desired non‐alternating in‐chain keto groups (1.0–9.3 mol %) and with tunable molecular weights ranging from 43 to 195 kDa. In this reaction, H2 serves as a chain transfer agent, modulating the polymer's molecular weight, forming unique aldehyde endgroups and eliminating usual olefinic endgroups; CO undergoes non‐alternating insertion into the PE chain, resulting in a strictly non‐alternating structure (>99 %) for the keto‐PE. The dispersed incorporation of in‐chain keto groups retains bulk properties of PE and makes PE susceptible to photodegradation, which produces significantly lower molecular weight polymers and oligomers with unambiguous vinyl and acetyl terminals. Starting from three large‐scale feedstocks of ethylene + carbon monoxide + hydrogen, direct hydrogen‐controlled non‐alternating copolymerization of CO and ethylene produces aldehyde end‐capped polyethylene (PE) materials with in‐chain isolated keto group, whose molecular weight and chain endgroup could be modulated by H2. Such semicrystalline PE could undergo photodegradation to oily derivatives.