Trinseo PLC

Trinseo's precursor Styron was formed in August 2009 when Dow Chemical Company combined several of its businesses-- styrenics; polycarbonate and compounds & blends; Dow Automotive plastics; emulsion polymers (paper and carpet latex); and synthetic rubber — as part of a larger process of identifying and selling non-strategic assets. Several private equity firms bid on Styron, including TPG Capital, Apollo Management, and Lotte Group. On March 2, 2010, Bain Capital announced that it would purchase the newly formed company for $1.63 billion, with Dow retaining a 7.5% stake. The sale was finalized in June 2010.

The name Trinseo was chosen in 2012. By February 2015, all legal entities worldwide had changed to the name Trinseo.

As of 2016, Bain sold all of its stock in Trinseo, grossing $1.69 billion for 37,269,567 shares, resulting in Trinseo's “full independence as a public company.” In November 2017, Trinseo started a MAGNUM ABS production line manufacturing plant at the Zhangjiagang, China site.

In March 2023, over 8,000 gallons of "latex finishing material" leaked into Otter Creek, a tributary of the Delaware River, from a Trinseo plant in Bucks County, Pennsylvania. Well over a million residents of nearby areas--including more than half of the city of Philadelphia --were at least temporarily urged not to drink their tap water because of potential toxic contamination from the leak, causing widespread panic and shortages of bottled water. Work at the plant, which had been responsible for at least four other contamination incidents since 2010, was temporarily halted by Trinseo. Shares of the company fell after the leak.

On May 26, 2026, Trinseo filed for Chapter 11 bankruptcy protection, citing weaker volumes and an unsustainable debt burden. The company is currently negotiating with lenders to reduce its debt and cut its interest costs. Trinseo listed assets and liabilities between $1 billion to $10 billion.