Functionalization of polyethylene with hydrolytically-stable ester groups

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Chemistry

Background:

• Polyethylene (PE) is a widely used plastic with limited functionalizability.
• Chemical modification of PE can enhance its properties and expand its applications.
• Developing efficient and sustainable methods for PE functionalization is crucial for plastic upcycling.

Purpose of the Study:

• To introduce ester functionalities into low-density (LD) and high-density polyethylene (HDPE).
• To investigate the hydrolytic stability of the modified polyethylene esters.
• To explore the potential for further chemical transformations of the upcycled materials.

Main Methods:

• Reaction of LD and HDPE with ethyl diazoacetate (EDA) under solvent-free conditions.
• Reaction of LD and HDPE with maleic anhydride (MA) and acrylates (AC) under catalytic radical conditions.
• Assessment of hydrolytic stability across a pH range of 0-14.
• Demonstration of further transformations into carboxylic acids, carboxylates, esters, and amides.

Main Results:

• Incorporation of up to 7 wt% ester groups into both LD and HDPE.
• The resulting polyethylene esters demonstrated high hydrolytic stability across extreme pH conditions (0-14).
• Successful conversion of the esterified polyethylene into carboxylic acids, carboxylates, other esters, and amides was achieved.

Conclusions:

• Chemical upcycling of LD and HDPE via esterification is feasible using EDA or MA/AC.
• The synthesized polyethylene esters possess robust hydrolytic stability, broadening their potential applications.
• The ester functionalities serve as versatile handles for further chemical derivatization, enabling the creation of novel polymer structures.