POLYONE CORPORATION Exhibit 31.1 CERTIFICATION I, Robert M. Patterson President and Chief Executive Officer February 13, 2015 POLYONE CORPORATION Exhibit 31.2 CERTIFICATION I, Bradley C. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

IATF Certificate Place and date: For the issuing office: Katy, TX, 10 December 2024 Revision 2 DNV - Business Assurance 1400 Ravello Drive, Katy, TX, 77449- 5164, USA Sherif Mekkawy Management Representative Lack of fulfilment of conditions as set out in the Certification Agreement may render this Certificate invalid. ACCREDITED UNIT: DNV Business Assurance USA Inc., 1400 Ravello Drive, Katy, TX, 77449-5164, USA - TEL: +1 281-396-1000. www.dnv.com Page 1 of 2 MANAGEMENT SYSTEM CERTIFICATE Certificate no.: 273138-2018-AQ-RGC-IATF IATF Certificate No: 0558323 Valid: 10 December 2024 – 09 December 2027 This is to certify that the management system of Polyone - Shenzhen Co., Ltd. No. 1, Qihang Industry Park, Haoxiang Road, Shajing Town, Baoan, Shenzhen, Guangdong, China 518104 (USI: C5M65R) and, if applicable, the remote supporting locations as mentioned in the Appendix accompanying this Certificate has been found to conform to the Quality Management System standard: IATF 16949:2016 This certificate is valid for the following scope: DESIGN AND MANUFACTURE OF PLASTIC COMPOUNDING MATERIAL EXCLUSION: NONE http://www.dnv.com Certificate no.: 273138-2018-AQ-RGC-IATF IATF Certificate No: 0558323 Place and date: Katy, TX, 10 December 2024 Lack of fulfilment of conditions as set out in the Certification Agreement may render this Certificate invalid.

POLYONE CORPORATION [THIS PAGE INTENTIONALLY LEFT BLANK] Exhibit 31.1 CERTIFICATION I, Robert M. Patterson Chairman, President and Chief Executive Officer February 16, 2017 POLYONE CORPORATION Exhibit 31.2 CERTIFICATION I, Bradley C. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

Date of registration: 2018/08/21 Published: 2018/08/23 Effective: 2018/08/21 ... 8. Date of registration: 2018/08/21 Published: 2018/08/23 Effective: 2018/08/21 ... 21. Registration number: B226205 Date of change: 2021/11/24 Date of registration: 2021/12/06 Effective: 2021/11/24 ... 2.

Exhibit Description 31.1 Certification of Robert M. POLYONE CORPORATION Exhibit 31.1 CERTIFICATION I, Robert M. POLYONE CORPORATION Exhibit 32.2 CERTIFICATION PURSUANT TO 18 U.S.C.

Kennedy Code postal 1855 Localité Luxembourg Pays Luxembourg Type de mandat Réviseur d'entreprises agréé Durée du mandat Date de nomination 01/07/2021 Durée du mandat Déterminée Date d'expiration du mandat 01/07/2024 Page 5 / 5 B226205 Pour extrait conforme [3] Luxembourg, le 16/11/2021 Pour le gestionnaire du registre de commerce et des sociétés [4] [1] Information mise à jour mensuellement sur base de l'article 12§3 de la loi modifiée du 19 décembre 2002 concernant le registre de commerce et des sociétés ainsi que la comptabilité et les comptes annuels des entreprises Si une modification a été notifiée au registre de commerce et des sociétés entre temps, il se peut qu'elle n'ait pas été prise en compte lors de l'émission de ce formulaire Le gestionnaire du registre de commerce et des sociétés ne garantit l'authenticité de l'origine et l'intégrité des informations contenues sur le présent extrait par rapport aux informations inscrites au registre de commerce et des sociétés que si le présent extrait comporte une signature électronique émise par le gestionnaire du registre de commerce et des sociétés. 2021-11-16T13:12:39+0000

MSC Certificate Place and date: For the issuing office: Shanghai, 10 October 2024 DNV - Business Assurance Building 9, No. 1591 Hongqiao Road, Changning District, Shanghai, China 200336 Zhu Hai Ming Management Representative Lack of fulfilment of conditions as set out in the Certification Agreement may render this Certificate invalid. ACCREDITED UNIT: DNV Business Assurance B.V., Zwolseweg 1, 2994 LB, Barendrecht, Netherlands - TEL: +31(0)102922689. www.dnv.com/assurance MANAGEMENT SYSTEM CERTIFICATE Certificate no.: 3033-2006-AQ-RGC-RvA Initial certification date: 07 November 2018 Valid: 08 November 2024 – 07 November 2027 This is to certify that the management system of Polyone - Shenzhen Co., Ltd. No. 1, Qihang Industry Park, Haoxiang Road, Shajing Town, Baoan, Shenzhen, Guangdong, China 518104 has been found to conform to the Quality Management System standard: GB/T 19001-2016 / ISO 9001:2015 This certificate is valid for the following scope: Development and Manufacture of Masterbatch, Pigment Concentration, Plastisol; Manufacture of Plastic Compounding Material http://www.dnv.com/assurance 证书制作地点及日期: 证书认可签发机构: 上海, 2024年10月 10日 DNV - Business Assurance 中国上海市长宁区虹桥路1591号9号楼A座 邮编: 200336 电话: +86 21 32799000 朱海明 管理代表 未履行认证协议中规定条款会导致此证书失效，获证组织必须定期接受监督审核并经审核合格此证书方继续有效。

We are proud to share that our associates feel we are a Great Place to Work® and, in 2023, we received our fifth certification. We hold the American Chemistry Council's certification as a Responsible Care Management System® (RCMS) company. The RCMS certification affirms the importance Avient places on having world-class environmental, health, safety and security performance.

Have appropriate licenses, registrations and certifications required to conduct business in the locations where you operate