POWER OF ATTORNEY

The undersigned hereby constitutes and appoints Angelo Chaclas,
Loretta DiLucido, Patricia Halberstadt, Craig Marcus, with full
power of substitution, as the undersigned's true and lawful
attorney-in-fact to:

   1) prepare, execute in the undersigned's name and on the
undersigned's behalf, and submit to the U.S.  Securities and
Exchange Commission (the "SEC")  a  Form  ID,  including
amendments thereto, and any other documents necessary or
appropriate to obtain codes and passwords enabling  the
undersigned to make electronic filings with the SEC of reports
required by Section 16(a) of the Securities Exchange Act of 1934
or any rule or regulation of the SEC;

   2) execute for and on behalf of the undersigned, in the
undersigned's capacity as officer and/or director of Trinseo S.A.
(the "Company"), Forms 3,  4,  and  5  in  accordance  with
Section 16(a) of the Securities Exchange Act of 1934 and the
rules thereunder;

   3) do and perform any and all acts for and on behalf of the
undersigned that may be necessary or desirable to complete and
execute any such Form 3, 4, or 5, complete and execute any
amendment or amendments thereto, and timely file such form with
the SEC and any stock exchange or similar authority; and

   4) take any other action of any type whatsoever in connection
with the foregoing that, in the opinion  of such attorney-in-
fact, may be of benefit to, in the best interest of, or legally
required by, the  undersigned, it being understood that the
documents executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in such
form and shall contain such terms and conditions as such
attorney-in-fact may approve in such attorney-in-fact's
discretion.

The undersigned hereby grants to such attorney-in-fact full power
and authority to do and perform any and every act and thing
whatsoever requisite, necessary, or proper to be done in the
exercise of any of the rights and powers herein granted, as fully
to all intents and purposes as the undersigned might or could do
if personally present, with full power of substitution or
revocation, hereby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or
substitutes, shall lawfully do or cause to be done by virtue of
this power of attorney and the rights and powers herein granted.
The undersigned acknowledges that the foregoing attorneys-in-
fact, in serving in such capacity at the request of the
undersigned, are not assuming, nor is the Company assuming, any
of the undersigned's responsibilities to comply with Section 16
of the Securities Exchange Act of 1934.

This Power of Attorney shall remain in full force and effect
until the undersigned is no longer required to file Forms 3, 4,
and 5 with respect to the undersigned's holdings of and
transactions in securities issued by the Company, unless earlier
revoked by the undersigned in a signed writing delivered to the
foregoing attorney-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of November 20, 2019.


/s/ Mark Tomkins
__________________

Name:  Mark Tomkins
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