# Coordinative Ring‐Opening Copolymerization of Limonene Carbamate and ε‐Caprolactone Toward Phosgene‐ and Isocyanate‐Free Polyesterurethane Block‐Copolymers with Tunable Properties

## TL;DR

This paper introduces a new eco-friendly method to make polyesterurethanes without toxic chemicals, resulting in materials with adjustable properties.

## Contribution

A sustainable, isocyanate- and phosgene-free synthesis route for polyesterurethanes using ring-opening copolymerization of limonene carbamate and ε-caprolactone.

## Key findings

- Block copolymers with tunable thermal and optical properties were synthesized and characterized.
- The method allows for adjustable glass transition temperatures and high transmittance in the resulting materials.
- The copolymers exhibit customizable mechanical properties, including high elongation at break.

## Abstract

Polyesterurethanes are versatile polymers widely utilized in applications such as foams and adhesives, yet their industrial production relies on toxic and carcinogenic diisocyanates. To address this, isocyanate‐ and phosgene‐free synthetic methods have been explored, with ring‐opening polymerization of cyclic carbamates emerging as a promising alternative. This study presents the coordinative ring‐opening copolymerization of limonene‐based cyclic carbamates with ε‐caprolactone to synthesize AB‐block polyesterurethanes. Using the presented method, tunable block copolymer compositions were achieved, verified by NMR, GPC, and FT‐IR analyses. Thermal and optical characterizations by DSC and UV–vis revealed an adjustable glass transition temperature between −9°C and −59°C and transmittance up to 84% for PLU‐b‐PCL (49:51), while tensile testing demonstrated customizable mechanical properties. Notably, PLU‐b‐PCL (5:95) exhibited an elongation at break of 582%. These findings provide a basis for sustainable polyesterurethane synthesis by ring‐opening copolymerization and demonstrate the versatility of this method.

This study presents a sustainable, isocyanate‐ and phosgene‐free route to polyesterurethanes via coordinative ring‐opening copolymerization of limonene carbamate and ε‐caprolactone. The resulting block copolymers show tunable thermal, optical, and mechanical properties, offering a green alternative for advanced polyurethane materials.