Exhibit 5.1

                                WINSTON & STRAWN
                              35 West Wacker Drive
                             Chicago, Illinois 60601


                               September 17, 2001

Solutia Inc.
CPFilms Inc.
Monchem, Inc.
Monchem International, Inc.
Solutia Systems, Inc.
575 Maryville Center Drive
P.O. Box 66760
St. Louis, Missouri 63166-6760

          RE:   REGISTRATION STATEMENT ON FORM S-4
                OF SOLUTIA INC. AND THE
                SUBSIDIARY GUARANTORS (AS DEFINED BELOW)

Ladies and Gentlemen:

     We have acted as special counsel to Solutia Inc., a Delaware corporation
(the "Company"), and certain of its subsidiaries (the "Subsidiary Guarantors")
in connection with the preparation of the Registration Statement on Form S-4
(the "Registration Statement") filed with the Securities and Exchange Commission
(the "Commission") on behalf of the Company and the Subsidiary Guarantors,
relating to the Company's offer to exchange $150 million aggregate principal
amount of the Company's 11.25% Senior Secured Notes due 2009 (the "New Notes")
and the Guarantees (as hereinafter defined) thereof by the Subsidiary
Guarantors, which are to be offered in exchange for an equivalent principal
amount of the Company's currently outstanding 11.25% Senior Secured Notes due
2009 (the "Old Notes"), all as more fully described in the Registration
Statement. The New Notes will be issued under the Company's Indenture, dated as
of July 9, 2002 (the "Original Indenture"), between SOI Funding Corp. and HSBC
Bank USA, as trustee (the "Trustee"), as amended and supplemented by the First
Supplemental Indenture dated as of July 25, 2002 (the "Supplemental Indenture"
and, together with the Original Indenture, the "Indenture"), among the Company,
the Trustee and the Subsidiary Guarantors. Capitalized terms used herein and not
otherwise defined shall have the meanings assigned to such terms in the
prospectus (the "Prospectus") contained in the Registration Statement.

     This opinion letter is delivered in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act of 1933, as amended
(the "Securities Act").

     In connection with this opinion, we have examined and are familiar with
originals or copies, certified or otherwise identified to our satisfaction, of
(i) the Registration Statement, in the form filed with the Commission and as
amended through the date hereof; (ii) the Certificate



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of Incorporation of the Company and each of the Subsidiary Guarantors, as
currently in effect; (iii) the By-laws of the Company and each of the Subsidiary
Guarantors, as currently in effect; (iv) the Indenture; (v) the form of the New
Notes; and (vi) resolutions of the Boards of Directors of the Company and each
of the Subsidiary Guarantors, relating to, among other things, the issuance and
exchange of the New Notes for the Old Notes, the issuance of the Guarantees and
the filing of the Registration Statement. We also have examined such other
documents as we have deemed necessary or appropriate as a basis for the opinions
set forth below.

     In our examination, we have assumed the legal capacity of all natural
persons, the genuineness of all signatures, the authenticity of all documents
submitted to us as originals, the conformity to original documents of all
documents submitted to us as certified or photostatic copies, and the
authenticity of the originals of such latter documents. As to certain facts
material to this opinion, we have relied without independent verification upon
oral or written statements and representations of officers and other
representatives of the Company and others.

     Based upon and subject to the foregoing, we are of the opinion that:

     1.   The issuance and exchange of the New Notes for the Old Notes and the
issuance of the Guarantees have been duly authorized by requisite corporate
action on the part of the Company and each Subsidiary Guarantor, respectively.

     2.   When (i) the Registration Statement, as finally amended (including all
necessary post-effective amendments), shall have become effective under the
Securities Act, (ii) the New Notes are duly executed and authenticated in
accordance with the provisions of the Indenture, and (iii) the New Notes shall
have been issued and delivered in exchange for the Old Notes pursuant to the
terms set forth in the Prospectus, the New Notes and the Guarantees will be
valid and binding obligations of the Company and the Subsidiary Guarantors,
respectively, entitled to the benefits of the Indenture and enforceable against
the Company and the Subsidiary Guarantors, respectively, in accordance with
their terms, except to the extent that the enforceability thereof may be limited
by (x) bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium
or other similar laws now or hereafter in effect relating to creditors' rights
generally and (y) general principles of equity (regardless of whether
enforceability is considered in a proceeding at law or in equity) when (i) the
Registration Statement, as finally amended (including all necessary
post-effective amendments), shall have become effective under the Securities
Act; (ii) the New Notes are duly executed and authenticated in accordance with
the provisions of the Indenture; and (iii) the New Notes shall have been issued
and delivered in exchange for the Old Notes pursuant to the terms set forth in
the Prospectus.

     The foregoing opinions are limited to the laws of the United States, the
State of New York and the General Corporation Law of the State of Delaware. We
express no opinion as to



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the application of the securities or blue sky laws of the various states to the
issuance or exchange of the New Notes.

     We hereby consent to the reference to our firm under the headings "Legal
Matters" in the Prospectus and to the filing of this opinion with the Commission
as an exhibit to the Registration Statement. In giving such consent, we do not
concede that we are experts within the meaning of the Securities Act or the
rules and regulations thereunder or that this consent is required by Section 7
of the Securities Act.

                                            Very truly yours,

                                            /s/ Winston & Strawn