Thermo-Rheological and Shape Memory Properties of Block and Random Copolymers of Lactide and ε-Caprolactone.

Marco Naddeo,Daniela Pappalardo,Andrea Sorrentino

doi:10.3390/polym13040627

Marco Naddeo, Daniela Pappalardo + Show 1 more

Open Access

https://doi.org/10.3390/polym13040627

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Abstract

Biodegradable block and random copolymers have attracted numerous research interests in different areas, due to their capability to provide a broad range of properties. In this paper, an efficient strategy has been reported for preparing biodegradable PCL-PLA copolymers with improved thermal, mechanical and rheological properties. Two block-copolymers are synthesized by sequential addition of the cyclic esters lactide (L-LA or D,L-LA) and ε-caprolactone (CL) in presence of a dimethyl(salicylaldiminato)aluminium compound. The random copolymer of L-LA and CL was synthetized by using the same catalyst. Chain structure, molar mass, thermal, rheological and mechanical properties are characterized by NMR, SEC, TGA, DSC, Rheometry and DMTA. Experimental results show that by changing the stereochemistry and monomer distribution of the copolymers it is possible to obtain a variety of properties. Promising shape-memory properties are also observed in the di-block copolymers characterized by the co-crystallization of CL and L-LA segments. These materials show great potential to substitute oil-based polymers for packaging, electronics, and medicine applications.

Highlights

Oil-derived polymers still dominate the market today, due to their low cost, high availability, and durability
Molar mass, thermal, rheological and mechanical properties are characterized by NMR, size exclusion chromatography (SEC), thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC), Rheometry and DMTA
Promising shape-memory properties are observed in the di-block copolymers characterized by the co-crystallization of CL and L-LA

Summary

Introduction

Oil-derived polymers still dominate the market today, due to their low cost, high availability, and durability. The problem related to their end-of-life disposal presents an environmental challenge that is no longer sustainable in the long term [1,2]. Constant scientific efforts have been dedicated to the production of synthetic biodegradable polymers with a reduced environmental impact [3]. Despite the huge amount of research efforts, the number of high-performance biodegradable polymers commercially available is still very limited. Linear aliphatic polyesters represent the class of biodegradable materials that are the most studied [4]. Among these polymers, the leading position is undoubtedly held by poly(lactide) (PLA) and poly(ε-caprolactone)

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