# Expanding the Chemical Space of Cyclic Polyphthalaldehyde via Post‐Functionalization

## TL;DR

Researchers created water-soluble cyclic polyphthalaldehyde polymers using a new post-functionalization method, enabling potential biological applications.

## Contribution

A novel post-functionalization strategy to make water-soluble cPPA polymers with high molecular weight.

## Key findings

- cPPA derivatives were made water-soluble through post-functionalization.
- Modified cPPA was taken up by cells and depolymerized in acidic lysosomes.
- The method uses click chemistry for efficient functionalization.

## Abstract

Cyclic polyphthalaldehydes (cPPAs) are hydrophobic cyclic polymers with stimuli‐responsive depolymerization property. The introduction of hydrophilic functionalities to cPPAs is challenging due to the intrinsic limitation of cationic polymerization. Herein, we developed a post‐functionalization approach to achieve water‐soluble cPPA derivatives with high molecular weight. The cPPA modified with cell‐penetrating oligoarginine underwent cellular uptake via endocytosis and acid‐triggered depolymerization in lysosome, which provided new potential for biological application.

In this work, we developed a post‐functionalization approach to achieve water‐soluble cyclic polyphthalaldehyde (cPPA) polymers via click chemistry.