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.

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

Garanzia Limitata Esclusiva Without prejudice to Section 3, Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis or a Certificate of Compliance or a Product Specification Sheet, if either such document exists, and other specifications signed by Seller (“Specifications”).

Seller warrants good and clear title in the Product and that the Product conforms at the time of shipment to Buyer a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, or in any other specifications either signed by Seller (“Specifications”).

Seller warrants good and clear title in goods subject to the sale (“Product”) and that the Product conforms at the time of shipment to a Certificate of Analysis, a Certificate of Compliance, or a Product Specification Sheet, if any such document exists, and other specifications signed by Seller (“Specifications”).

All Rights Reserved 2024 33 Drug delivery devices CATALYZE THE CORE M ARKET DRIVERS & NEEDS • Regulatory compliance • Reliable material quality and uninterrupted supply • Supply chain risk mitigation • Global reach $6B ADDRESSABLE MARKET A V I E N T E N D M A R K E T S , A P P L I C A T I O N S AVIENT VALUE PROPOSITION • ISO 13485 accredited sites • Globally approved raw material portfolio • Strict change management • Global supply Auto injectors Syringes Inhalers OTHER APPLICATONS • In-vitro diagnostics • Remote monitoring • Pharma packaging • Catheters • Medical equipment Copyright © .

Global Compact • Highlights ESG Performance, including ratings, awards, and certifications • Features increased carbon emissions disclosures, including Climate Change Scenario Analysis and Scope 3 emissions data • Outlines Sustainable Supplier Program, designed to enable supplier evaluation & collaboration • Reflects Great Place To Work® culture focused on safety, employee engagement and advancing diversity, equity and inclusion 20 22 SUSTAI NA BILI TY REPORT 19 Avient Confidential 20 • Virtual presentation to be held September 20, 2023 • Leadership will be conducting an investor-focused presentation around our sustainable solutions portfolio • Deep dive into how we enable customers to achieve their sustainability goals SUSTAINABILITY DAY 20 …are Growing at Twice the Rate as Conventional Products Sustainably-Branded Products… STAKEHOLD ER INFLUENC E D RI VES D EMA ND Consumers Are demanding recyclability and eco- conscious products Governments Are mandating changes through legislation, taxes, and regional accords Brand Owners Have committed to ambitious goals to achieve sustainability metrics 21 A P P E N D I X 24 Performance Additives 16% Pigments 12% TiO2 10% Dyestuffs 2% Polyethylene 11% Nylon 6% Polypropylene 5% Styrenic Block Copolymer 5% Other Raw Materials 33% ~40% hydrocarbon based (Grey shaded materials are hydrocarbon based, includes portion of “Other Raw Materials”) Non-hydrocarbon based materials 2022 pro forma results for the acquisition of Avient Protective Materials RA W MATERI AL BA SKET PEER COMPARISONS AVI ENT I S ASSET LI GHT Capex / Revenue 2023E (%) Avient Specialty Formulators Other Specialty / Chemical Companies Source: Peer data per Bloomberg as of August 17, 2023 Note: Avient reflects 2023 estimated revenue of $3,280 and estimated run-rate CAPEX of $110M. 26 3 2 3 3 4 4 3 4 5 5 7 7 9 10 A vi e n t K W R P P G F U L A V Y R P M F M C H U N C E E C L A S H H X L E M N S C L FR EE CA SH FLOW CONV ER SION Source: Peer data per Bloomberg as of August 17, 2023 Note: Free cash flow conversion calculated as (Adjusted EBITDA – Capex) / Adjusted EBITDA.

Global Compact & fulfilled Communication of Progress (COP) requirements • New Sustainability Strategy overview page including our 2022 AIP ESG metrics • New ESG Performance page with ESG ratings, awards, and certifications • Increased disclosures on carbon emissions, including disclosure of Climate Change Scenario Analysis • Added new Product Stewardship and Chemical Management policies • Enhanced data reporting for Workforce Demographics • Improved social disclosures on human rights, dependent care and special leave and strategic training management 20 21 SUSTAI NA BILI TY REPORT Launching integrated sustainability website in parallel with report Aligned with leading reporting frameworks 9 ESG PER FORMANCE & A WAR DS 10 84th ENVIRONMENTAL SOCIAL GOVERNANCE 2 1 3 (as of 6/30/22) 2 0 2 2 O U T L O O K $429 $490 2021 2022E $3.05 $3.50 2021 2022E FY 2022 GUIDANCE ( T O TA L C O M PA N Y: C U R R E N T P O R T F O L I O ) 12 Sales Adjusted Operating Income $4,819 $5,100 2021 2022E + 6% Adjusted EPS + 14% + 15% (in millions) (in millions) (+ 9% excluding FX) (+ 18% excluding FX) (+ 20% excluding FX) 13 CA SH FLOW / LEV ER AGE ($ millions) 2022E Cash Flow from Operating Activities 400$ Less: Run-Rate CapEx (90) CapEx for Clariant Integration (10) CapEx for IT System Upgrade (15) Total CapEx (115) Free Cash Flow 285$ Adjusted EBITDA 635$ Net Debt / Adjusted EBITDA 1.6x 14 DYNEEMA / DI STRIBUTION UPDATES • Strong performance so far in 2022 in-line with our modeling • Acquisition to be finalized as early as September 1, pending standard regulatory process and closing conditions • Encouraging interest thus far from potential buyers for world-class business with a strong track record • Second round bids due in August DISTRIBUTION 15 PRO F OR MA MODELI NG UPDATE 2022E ($M) Revenue 5,100$ 415$ 5,515$ (1,635)$ 3,880$ Adjusted EBITDA 635 130 765 (109) 656 EBITDA % 12% 31% 14% 7% 17% Adj.