UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): April 3, 2025

Trinseo PLC

(Exact name of registrant as specified in its charter)


Ireland	001-36473	N/A
(State or other jurisdiction of incorporation or organization)	(Commission File Number)	(I.R.S. Employer Identification Number)

440 East Swedesford Road, Suite 301,

Wayne, Pennsylvania 19087

(Address of principal executive offices, including zip code)

(610) 240-3200

(Telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:


Title of Each Class	Trading symbol(s)	Name of Each Exchange on which registered
Ordinary Shares, par value $0.01 per share	TSE	New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

ITEM 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(b) Departure of Directors or Certain Officers

Retirement Announcement from Pierre-Marie De Leener and Mark Tomkins

On April 3, 2025, Pierre-Marie De Leener and Mark Tomkins, two members of the Board of Directors (the “Board”) of Trinseo PLC (the “Company”), notified the Company of their decision to retire from the Board and not stand for reelection at the Company’s 2025 annual general meeting of shareholders. Following the annual general meeting, the size of the Board is expected to be decreased to nine members. The decision by Mr. De Leener and Mr. Tomkins to retire as directors of the Company was not the result of any disagreement with the Company on any matter relating to the operations, internal controls, policies or practices of the Company.

Mr. De Leener has served on the Board since the Company’s IPO in 2014, and Mr. Tomkins has served since 2019. The Company and the Board are grateful for their many years of dedicated service.

ITEM 9.01	Exhibits.
104	Cover Page Interactive Data File (formatted in Inline XBRL and contained in Exhibit 101)

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	TRINSEO PLC


	By:	/s/ Angelo Chaclas
	Name:	Angelo Chaclas
	Title:	Senior Vice President and Chief Legal Officer

Date: April 4, 2025