Functional Self-Healing Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: closed (30 April 2024) | Viewed by 6121

Special Issue Editors


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Guest Editor
Advanced Materials Research Center, Technology Innovation Institute, Masdar City, Abu Dhabi, United Arab Emirates
Interests: self-healing materials; polymers; compatibilization; surface modification
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Guest Editor
CERENA, Chemical Engineering Department, Instituto Superior Técnico (IST), Universidade de Lisboa, Lisboa, Portugal
Interests: technology platform on microencapsulation and immobilization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Self-healing materials are a class of smart materials that have a great deal of potential for advanced engineering systems. These systems can respond to environmental stimuli in a non-linear and productive way without the need for external intervention. Self-healing science and technology have expanded at a higher pace in the recent decade than in those before, resulting in the creation of new polymers, polymer blends, polymer composites, and hybrid materials with self-healing characteristics. Due to their unique qualities, self-healing materials are used in a variety of fields, including biomedical, electrical, aerospace, coatings, and more. The aim of this Special Issue is to provide readers with an up-to-date overview of recent progress in research on self-healing materials and devices. 

Dr. Nataša Z. Tomić
Dr. Ana Marques
Guest Editors

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Keywords

  • self-healing
  • polymer blends
  • polymer
  • composites
  • hybrid materials
  • electrical devices

Published Papers (4 papers)

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Research

24 pages, 6315 KiB  
Article
Dynamic Non-Covalent Exchange Intrinsic Self-Healing at 20 °C Mechanism of Polyurethane Induced by Interactions among Polycarbonate Soft Segments
by Yuliet Paez-Amieva and José Miguel Martín-Martínez
Polymers 2024, 16(7), 924; https://doi.org/10.3390/polym16070924 - 27 Mar 2024
Viewed by 740
Abstract
Two polyurethanes (PUs) were similarly synthesized by reacting a cycloaliphatic isocyanate with 1,4-butanediol and two polyols of different nature (polyester, polycarbonate diol) with molecular weights of 1000 Da. Only the PU synthesized with polycarbonate diol polyol (YCD) showed intrinsic self-healing at 20 °C. [...] Read more.
Two polyurethanes (PUs) were similarly synthesized by reacting a cycloaliphatic isocyanate with 1,4-butanediol and two polyols of different nature (polyester, polycarbonate diol) with molecular weights of 1000 Da. Only the PU synthesized with polycarbonate diol polyol (YCD) showed intrinsic self-healing at 20 °C. For assessing the mechanism of intrinsic self-healing of YCD, a structural characterization by molecular weights determination, infrared and X-ray photoelectronic spectroscopies, differential scanning calorimetry, X-ray diffraction, thermal gravimetric analysis, and dynamic mechanical thermal analysis was carried out. The experimental evidence concluded that the self-healing at 20 °C of YCD was due to dynamic non-covalent exchange interactions among the polycarbonate soft segments. Therefore, the chemical nature of the polyol played a key role in developing PUs with intrinsic self-healing at 20 °C. Full article
(This article belongs to the Special Issue Functional Self-Healing Polymers)
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17 pages, 4577 KiB  
Article
Preparation and Characterization of a Series of Self-Healable Bio-Based Poly(thiourethane) Vitrimer-like Materials
by Federico Guerrero, Xavier Ramis, Silvia De la Flor and Àngels Serra
Polymers 2023, 15(6), 1583; https://doi.org/10.3390/polym15061583 - 22 Mar 2023
Cited by 3 | Viewed by 1731
Abstract
A series of poly(thiourethanes) (PTUs) from biobased monomers have been synthesized. Limonene and squalene were transformed into polyfunctional thiols by thiol-ene reaction with thioacetic acid and further saponification. They were then reacted in different proportions with hexamethylene diisocyanate (HDI) in the presence of [...] Read more.
A series of poly(thiourethanes) (PTUs) from biobased monomers have been synthesized. Limonene and squalene were transformed into polyfunctional thiols by thiol-ene reaction with thioacetic acid and further saponification. They were then reacted in different proportions with hexamethylene diisocyanate (HDI) in the presence of a catalyst to prepare bio-based poly(thiourethane) vitrimer-like materials. The different functionalities of squalene and limonene thiols (six and two, respectively) allow for changing the characteristics of the final material by only varying their relative proportions in the reactive mixture. The proportions of thiol and isocyanate groups were stoichiometric in all the formulations tested. An acidic and a basic catalyst were tested in the preparation of the networked polymers. As the acidic catalyst, we selected dibutyltin dilaurate (DBTDL), and as the basic catalyst, a tetraphenylborate salt of 1,8-diazabicyclo(5.4.0)undec-7-ene (BGDBU), which has the advantage of only releasing the base at high temperatures. The materials obtained were characterized by thermogravimetry and thermomechanical analysis. The vitrimeric-like behavior was evaluated, and we could see that higher proportions of the limonene derivative in the formulations led to faster stress relaxation of the material. The use of the base catalyst led to a much shorter relaxation time. The materials obtained demonstrated good self-healing efficiency. Full article
(This article belongs to the Special Issue Functional Self-Healing Polymers)
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13 pages, 3640 KiB  
Article
Enhancement of Self-Healing Efficacy of Conductive Nanocomposite Hydrogels by Polysaccharide Modifiers
by Nataša Z. Tomić, Myriam Ghodhbane, Zineb Matouk, Nujood AlShehhi and Chiara Busà
Polymers 2023, 15(3), 516; https://doi.org/10.3390/polym15030516 - 18 Jan 2023
Cited by 1 | Viewed by 1756
Abstract
The proper design of a polysaccharide/hydrocolloid modifier significantly affects the conductivity, self-healing, and viscoelastic properties of nanocomposite hydrogels. Due to the presence of different functional groups, these hydrogels can participate in the covalent, hydrogen and dynamic bonding of a system. The improvement of [...] Read more.
The proper design of a polysaccharide/hydrocolloid modifier significantly affects the conductivity, self-healing, and viscoelastic properties of nanocomposite hydrogels. Due to the presence of different functional groups, these hydrogels can participate in the covalent, hydrogen and dynamic bonding of a system. The improvement of interactions in this system can lead to the development of high-performance nanocomposite hydrogels. In this study, resilient, self-healing and self-adhesive conductive nanocomposite hydrogels were produced by multiple and diverse coordination connections between various polysaccharide-based modifiers (Arabic gum, sodium carboxymethyl cellulose, and xanthan), the poly(vinyl alcohol) (PVA) network and different graphene-based fillers. Graphene nanoplatelets (GNP), activated carbon black (ACB), and reduced graphene oxide (rGO) have distinct functionalized surfaces, which were analyzed by X-ray photoelectron spectroscopy (XPS). Furthermore, the introduction of fillers balanced the hydrogels’ viscoelastic properties and electrical conductivity, providing the hydrogels with resilience, improved electrical conductivity, and extreme stretchability (5000%). The self-healing properties were analyzed using time-dependent measurements in a shear strain mode using an RSO Rheometer. The improvement in electrochemical and conductivity properties was confirmed by electrochemical impedance spectroscopy (EIS). The obtained conductive nanocomposite hydrogels design opens new possibilities for developing high-performance polysaccharide-based hydrogels with wearable electrical sensors and healthcare monitoring applications. Full article
(This article belongs to the Special Issue Functional Self-Healing Polymers)
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15 pages, 5431 KiB  
Article
An Analysis of the Effect of Activation Temperature and Crack Geometry on the Healing Efficiency of Polycaprolactone (PCL)/Epoxy Blends
by Rocío Calderón-Villajos, Xoan Fernández Sánchez-Romate, Alberto Jiménez-Suárez and Silvia González Prolongo
Polymers 2023, 15(2), 336; https://doi.org/10.3390/polym15020336 - 9 Jan 2023
Cited by 3 | Viewed by 1338
Abstract
Self-healing materials have attracted great interest in recent years. Particularly, the use of thermoset/thermoplastics blends has emerged as a good option with relatively low activation temperatures and potential infinite healing cycles. Nevertheless, a methodical study of healing conditions and evaluation is still required [...] Read more.
Self-healing materials have attracted great interest in recent years. Particularly, the use of thermoset/thermoplastics blends has emerged as a good option with relatively low activation temperatures and potential infinite healing cycles. Nevertheless, a methodical study of healing conditions and evaluation is still required for further industrial development. The effect of activation temperature and crack morphology in polycaprolactone (PCL)/epoxy blends are explored. For this purpose, PCL content was varied (5, 10, and 15 wt %) with contents lower than critical composition. Therefore, the morphology of all studied blends is the epoxy matrix with a separated PCL phase. In this sense, an increase in PCL content leads to a reduction in the Tg, due to the partial PCL miscibility, and the presence of larger PCL domains. It was observed that a higher temperature (150 °C) and PCL content led to a more efficient self-healing process because of both the lower viscosity of the melted PCL at higher temperatures and the presence of larger PCL reservoirs when increasing the PCL content. Crack morphology influence was studied by inducing cracks with different tools: a custom crack machine with a cutting blade, a scalpel, and a pin. The results show that the recovery was better when the cracks were smaller and shallower, that is, with the pin. In addition, the healing efficiency by means of both parameters, crack volume and depth change, showed more similar results in slimmer cracks, due to a lower crack width-to-depth ratio. Full article
(This article belongs to the Special Issue Functional Self-Healing Polymers)
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