Parent and Wu reported PEO functionalization via a reactive radical formed by dicumyl peroxide, which was then trapped with an alkyne moiety to avoid undesirable chain-coupling or chain-scission. However, this report only demonstrated the functionalization of ethyl propionate. Recently, Zeng and coworkers developed a method for controllable C-H alkylation of polyethers using iron photocatalysis, leading to a successful versatile functionalization. The intermediate radicals generated under mild photocatalytic conditions coupled with electron deficient alkenes, while endured undesired degradations. In this paper, we disclose a condition for the direct attachment of carboxylic acids to PEO. The fully organocatalytic system can accommodate a broad scope of structurally diverse aromatic and aliphatic carboxylic acids, including biologically active ones. The resulting functional PEO now features a degradable acetal unit. The chemical and biological study of degradation and molecular delivery successfully demonstrate the hydrolysis of the acetal unit, which yields short PEO fragments and a carboxylic acid, making it highly desirable for PEObased drug delivery.