Self-repairing polymers are gaining ever-increasing attention and are becoming very appealing for future sustainable societies because they can enhance the durability of materials. A route to develop intrinsically self-repairing materials is the design of self-assembling supramolecular polymers, such as those bearing self-complementary hydrogen bonding 2-ureido-4[1H]-pyrimidinone (UPy) motifs. A deeper understanding of the self-assembly dynamics of UPy groups in supramolecular polymers is essential for controlling and exploiting their self-healing behavior. Here, two model copolymers with different molecular weights, made of butyl acrylate (BA) and a methacrylate comonomer bearing UPy groups, are synthesized. The copolymer molecular weight has an effect on glass transition temperatures, thermo-mechanical properties, and self-healing abilities. A lower polymer molecular weight increases chain mobility and decreases the glass transition temperature, thus improving self-repairing capabilities. Fourier-transform Infrared (FT-IR) spectroscopy analysis performed on UPy-BA copolymers with a more efficient self-healing behavior indicates the presence of specific markers for the formation of UPy-UPy dimers and for the breakage of multiple hydrogen bonds between UPy units. The results first demonstrate the possibility to monitor the supramolecular UPy assembly by vibrational spectroscopy during heat-triggered healing. This study enables self-healing properties of UPy-based copolymers at the macroscopic scale to be directly linked with the formation of UPy-UPy dimers acting as physical cross-links at the nanoscale.

A deep insight into the intrinsic healing mechanism in ureido-pyrimidinone copolymers

Suriano, Raffaella;Brambilla, Luigi;Tommasini, Matteo;Turri, Stefano
2018

Abstract

Self-repairing polymers are gaining ever-increasing attention and are becoming very appealing for future sustainable societies because they can enhance the durability of materials. A route to develop intrinsically self-repairing materials is the design of self-assembling supramolecular polymers, such as those bearing self-complementary hydrogen bonding 2-ureido-4[1H]-pyrimidinone (UPy) motifs. A deeper understanding of the self-assembly dynamics of UPy groups in supramolecular polymers is essential for controlling and exploiting their self-healing behavior. Here, two model copolymers with different molecular weights, made of butyl acrylate (BA) and a methacrylate comonomer bearing UPy groups, are synthesized. The copolymer molecular weight has an effect on glass transition temperatures, thermo-mechanical properties, and self-healing abilities. A lower polymer molecular weight increases chain mobility and decreases the glass transition temperature, thus improving self-repairing capabilities. Fourier-transform Infrared (FT-IR) spectroscopy analysis performed on UPy-BA copolymers with a more efficient self-healing behavior indicates the presence of specific markers for the formation of UPy-UPy dimers and for the breakage of multiple hydrogen bonds between UPy units. The results first demonstrate the possibility to monitor the supramolecular UPy assembly by vibrational spectroscopy during heat-triggered healing. This study enables self-healing properties of UPy-based copolymers at the macroscopic scale to be directly linked with the formation of UPy-UPy dimers acting as physical cross-links at the nanoscale.
FTIR spectroscopy; mechanical properties; self-complementary hydrogen bonding; self-healing; supramolecular structures; Polymers and Plastics
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/1080240
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