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ULISSE (STEPS) - MICS
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ULISSE (STEPS)

PROJECT

ULISSE (STEPS)

Thermoplastic elastomers from renewable sources, degradable and recyclable, as a potential alternative to traditional rubber in the footwear industry
PROJECT LEAD

Claudio Pellecchia

CONCEPT

The project aims to synthesize and characterize novel thermoplastic elastomers derived from renewable raw materials, with properties similar to SBS rubber. The materials under development are ABA triblock copolymers, where A is a “rigid” block and B is a flexible block. These copolymers are based on bio-derived, biodegradable aliphatic polyesters:

  • Poly(lactic acid) (PLA) for the rigid A blocks
  • Homo- and copolymers of δ- and ξ-lactones for the central flexible B block

These ABA copolymers will be synthesized through ring-opening polymerization (ROP), allowing precise control over block structure, composition, and length to tailor thermal, mechanical, and degradation properties.

CONTEXT

The footwear industry currently uses styrene-butadiene-styrene (SBS) rubber for shoe soles. SBS is a thermoplastic elastomer made up of two polystyrene “rigid” blocks and a central amorphous polybutadiene “flexible” block. Its structure creates physical cross-links that can be removed by heating—unlike chemically cross-linked rubbers.

However, SBS is derived from fossil sources and is non-biodegradable. As such, the project explores biodegradable, recyclable thermoplastic elastomers made from renewable feedstocks, aligned with circular economy goals.

Beneficiari

OBJECTIVES AND EXPECTED RESULTS

The main objective is to develop ABA triblock thermoplastic elastomers composed of bio-based, biodegradable aliphatic polyesters, ideal for a sustainable polymer industry. These materials are:

  • Renewable
  • Biodegradable
  • Mechanically or chemically recyclable

A key polymer in this class is PLA (Poly(lactic acid)), currently produced at over 400,000 tons/year via ROP of lactide, a dimer from biomass fermentation. PLA is a semi-crystalline polymer with a melting temperature (Tm) of ~170 °C and a glass transition temperature (Tg) of ~65 °C, showing properties comparable to polystyrene.

In the ABA structure:

  • PLA is used for the rigid A blocks
  • The flexible B block is based on δ-lactones, naturally occurring cyclic esters obtained from biomass, already used as flavoring agents or fragrances in the food and cosmetic industries.

Specifically, polymers from δ-hexalactone and its copolymers with ξ-caprolactone have already been prepared. Poly(δ-hexalactone) has a Tg < –60 °C and can be quantitatively depolymerized under mild conditions, making it particularly suitable for circular production processes.

KEY FIGURES

6

RESEARCHERS INVOLVED

4170

RESEARCH HOURS

16

PROJECT DURATION

3

NUMBER OF WORK PACKAGES (WPS)

1-2

STARTING TRL

4

FINAL TRL