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15 pages, 7378 KiB

Open AccessArticle

Binary Double Network-like Structure: An Effective Energy-Dissipation System for Strong Tough Hydrogel Design

by Genxin Chen, Sijie Tang, Honghan Yan, Xiongbin Zhu, Huimin Wang, Liya Ma, Kang Mao, Changying Yang and Jiabing Ran

Polymers 2023, 15(3), 724; https://doi.org/10.3390/polym15030724 - 31 Jan 2023

Cited by 3 | Viewed by 2028

Abstract

Currently, hydrogels simultaneously featuring high strength, high toughness, superior recoverability, and benign anti-fatigue properties have demonstrated great application potential in broad fields; thus, great efforts have been made by researchers to develop satisfactory hydrogels. Inspired by the double network (DN)-like theory, we previously [...] Read more.

Currently, hydrogels simultaneously featuring high strength, high toughness, superior recoverability, and benign anti-fatigue properties have demonstrated great application potential in broad fields; thus, great efforts have been made by researchers to develop satisfactory hydrogels. Inspired by the double network (DN)-like theory, we previously reported a novel high-strength/high-toughness hydrogel which had two consecutive energy-dissipation systems, namely, the unzipping of coordinate bonds and the dissociation of the crystalline network. However, this structural design greatly damaged its stretchability, toughness recoverability, shape recoverability, and anti-fatigue capability. Thus, we realized that a soft/ductile matrix is indispensable for an advanced strong tough hydrogel. On basis of our previous work, we herein reported a modified energy-dissipation model, namely, a “binary DN-like structure” for strong tough hydrogel design for the first time. This structural model comprises three interpenetrated polymer networks: a covalent/ionic dually crosslinked tightened polymer network (stiff, first order network), a constrictive crystalline polymer network (sub-stiff, second order network), and a ductile/flexible polymer network (soft, third order network). We hypothesized that under low tension, the first order network served as the sacrificing phase through decoordination of ionic crosslinks, while the second order and third order networks together functioned as the elastic matrix phase; under high tension, the second order network worked as the energy dissipation phase (ionic crosslinks have been destroyed at the time), while the third order network played the role of the elastic matrix phase. Owing to the “binary DN-like” structure, the as-prepared hydrogel, in principle, should demonstrate enhanced energy dissipation capability, toughness/shape recoverability, and anti-fatigue/anti-tearing capability. Finally, through a series of characterizations, the unique “binary DN-like” structure was proved to fit well with our initial theoretical assumption. Moreover, compared to other energy-dissipation models, this structural design showed a significant advantage regarding comprehensive properties. Therefore, we think this design philosophy would inspire the development of advanced strong tough hydrogel in the future. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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24 pages, 7364 KiB

Open AccessArticle

An Interpenetrating Polymer Network Hydrogel Based on Cellulose, Applied to Remove Colorant Traces from the Water Medium: Electrostatic Interactions Analysis

by Meriem Mihoub, Salah Hamri, Tewfik Bouchaour, Marcel Popa, Dragos Marius Popa, Lamia Bedjaoui Alachaher and Mihaela Hamcerencu

Polymers 2022, 14(23), 5090; https://doi.org/10.3390/polym14235090 - 23 Nov 2022

Cited by 4 | Viewed by 1807

Abstract

The main objective of this work was the removal of eosin Y and green malachite from an aqueous medium by using a cellulose-based biodegradable interpenetrated network (IPN). The IPN was obtained by the sequenced synthesis method. In the first step, cellulose was crosslinked [...] Read more.

The main objective of this work was the removal of eosin Y and green malachite from an aqueous medium by using a cellulose-based biodegradable interpenetrated network (IPN). The IPN was obtained by the sequenced synthesis method. In the first step, cellulose was crosslinked with epichlorohydrin (ECH). In the second step, the obtained gels were swollen in a reactive mixture solution, which was based on the monomers 2-hydroxyethyl methacrylate (HEMA) and 1,6- hexanediol diacrylate (HDDA). After this, swelling equilibrium was reached through the gels’ exposition to UV radiation. An infrared spectroscopy (FTIR) was used to analyze the bond stretching, which confirmed the IPN’s formation. The swelling kinetics in aqueous mediums with different pH values showed a high swelling at a basic pH value and a low response in neutral and acidic media. The IPNs showed an improvement in water uptake, compared to the networks based on PHEMA or cellulose. The IPN was used to remove dyes from the water. The results showed that a high percentage of green malachite was removed by the IPN in six minutes of contact time. The experimental results were confirmed by the docking/modeling method of the system (IPN/Dye). The different physical interactions between the IPN and the dyes’ molecules were investigated. The interactions of the hydrogen bonds with malachite green were stronger than those with eosin Y, which was in good agreement with the experimental results. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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19 pages, 6003 KiB

Open AccessArticle

Humins Blending in Thermoreversible Diels–Alder Networks for Stiffness Tuning and Enhanced Healing Performance for Soft Robotics

by Kenneth Cerdan, Joost Brancart, Ellen Roels, Bram Vanderborght and Peter Van Puyvelde

Polymers 2022, 14(9), 1657; https://doi.org/10.3390/polym14091657 - 20 Apr 2022

Cited by 8 | Viewed by 2663

Abstract

Humins waste valorization is considered to be an essential pathway to improve the economic viability of many biorefinery processes and further promote their circularity by avoiding waste formation. In this research, the incorporation of humins in a Diels–Alder (DA) polymer network based on [...] Read more.

Humins waste valorization is considered to be an essential pathway to improve the economic viability of many biorefinery processes and further promote their circularity by avoiding waste formation. In this research, the incorporation of humins in a Diels–Alder (DA) polymer network based on furan-maleimide thermoreversible crosslinks was studied. A considerable enhancement of the healing efficiency was observed by just healing for 1 h at 60 °C at the expense of a reduction of the material mechanical properties, while the unfilled material showed no healing under the same conditions. Nevertheless, the thermal healing step favored the irreversible humins polycondensation, thus strengthening the material while keeping the enhanced healing performance. Our hypothesis states a synergistic healing mechanism based on humins flowing throughout the damage, followed by thermal humins crosslinking during the healing trigger, together with DA thermoreversible bonds recombination. A multi-material soft robotic gripper was manufactured out of the proposed material, showing not only improved recovery of the functional performance upon healing but also stiffness-tunable features by means of humins thermal crosslinking. For the first time, both damage healing and zone reinforcement for further damage prevention are achieved in a single intrinsic self-healing system. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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17 pages, 4935 KiB

Open AccessArticle

The Influence of the Furan and Maleimide Stoichiometry on the Thermoreversible Diels–Alder Network Polymerization

by Ali Safaei, Seppe Terryn, Bram Vanderborght, Guy Van Assche and Joost Brancart

Polymers 2021, 13(15), 2522; https://doi.org/10.3390/polym13152522 - 30 Jul 2021

Cited by 16 | Viewed by 3016

Abstract

In recent work, the thermoreversible Diels–Alder reaction between furan and maleimide functional groups has been studied extensively in the context of self-healing elastomers and thermosets. To elaborate the influence of the stoichiometric ratio between the maleimide and furan reactive groups on the thermomechanical [...] Read more.

In recent work, the thermoreversible Diels–Alder reaction between furan and maleimide functional groups has been studied extensively in the context of self-healing elastomers and thermosets. To elaborate the influence of the stoichiometric ratio between the maleimide and furan reactive groups on the thermomechanical properties and viscoelastic behavior of formed reversible covalent polymer networks, a series of Diels–Alder-based networks with different stoichiometric ratios was synthesized. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and dynamic rheology measurements were performed on the reversible polymer networks, to relate the reversible network structure to the material properties and reactivity. Such knowledge allows the design and optimization of the thermomechanical behavior of the reversible networks for intended applications. Lowering the maleimide-to-furan ratio creates a deficit of maleimide functional groups, resulting in a decrease in the crosslink density of the system, and a consequent decrease in the glass transition temperature, Young’s modulus, and gel transition temperature. The excess of unreacted furan in the system results in faster reaction and healing kinetics and a shift of the reaction equilibrium. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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15 pages, 7265 KiB

Open AccessArticle

Thermally Remendable Polyurethane Network Cross-Linked via Reversible Diels–Alder Reaction

by Elena Platonova, Islam Chechenov, Alexander Pavlov, Vitaliy Solodilov, Egor Afanasyev, Alexey Shapagin and Alexander Polezhaev

Polymers 2021, 13(12), 1935; https://doi.org/10.3390/polym13121935 - 10 Jun 2021

Cited by 9 | Viewed by 2924

Abstract

We prepared a series of thermally remendable and recyclable polyurethanes crosslinked via reversible furan-maleimide Diels–Alder reaction based on TDI end-caped branched Voranol 3138 terminated with difurfurylamine and 4,4′-bis(maleimido)diphenylmethane (BMI). We showed that Young modulus strongly depends on BMI content (from 8 to 250 [...] Read more.

We prepared a series of thermally remendable and recyclable polyurethanes crosslinked via reversible furan-maleimide Diels–Alder reaction based on TDI end-caped branched Voranol 3138 terminated with difurfurylamine and 4,4′-bis(maleimido)diphenylmethane (BMI). We showed that Young modulus strongly depends on BMI content (from 8 to 250 MPa) that allows us to obtain materials of different elasticity as simple as varying BMI content. The ability of DA and retro-DA reactions between furan and maleimide to reversibly bind material components was investigated by NMR spectroscopy, differential scanning calorimetry, and recycle testing. All polymers obtained demonstrated high strengths and could be recovering without significant loss in mechanical properties for at least five reprocessing cycles. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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16 pages, 1114 KiB

Open AccessArticle

Theoretical Characterization of New Frustrated Lewis Pairs for Responsive Materials

by Maialen Galdeano, Fernando Ruipérez and Jon M. Matxain

Polymers 2021, 13(10), 1573; https://doi.org/10.3390/polym13101573 - 14 May 2021

Cited by 1 | Viewed by 2177

Abstract

In recent years, responsive materials including dynamic bonds have been widely acclaimed due to their expectation to pilot advanced materials. Within these materials, synthetic polymers have shown to be good candidates. Recently, the so-called frustrated Lewis pairs (FLP) have been used to create [...] Read more.

In recent years, responsive materials including dynamic bonds have been widely acclaimed due to their expectation to pilot advanced materials. Within these materials, synthetic polymers have shown to be good candidates. Recently, the so-called frustrated Lewis pairs (FLP) have been used to create responsive materials. Concretely, the activation of diethyl azodicarboxylate (DEAD) by a triphenylborane (TPB) and triphenylphosphine (TPP) based FLP has been recently exploited for the production of dynamic cross-links. In this work, we computationally explore the underlying dynamic chemistry in these materials, in order to understand the nature and reversibility of the interaction between the FLP and DEAD. With this goal in mind, we first characterize the acidity and basicity of several TPB and TPP derivatives using different substituents, such as electron-donating and electron-withdrawing groups. Our results show that strong electron-donating groups increase the acidity of TPB and decrease the basicity of TPP. However, the FLP–DEAD interaction is not mainly dominated by the influence of these substituents in the acidity or basicity of the TPB or TPP systems, but by attractive or repulsive forces between substituents such as hydrogen bonds or steric effects. Based on these results, a new material is proposed based on FLP–DEAD complexes. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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10 pages, 3533 KiB

Open AccessArticle

Light Scattering and Rheological Studies of 3D/4D Printable Shape Memory Gels Based on Poly (N,N-Dimethylacrylamide-co-Stearyl Acrylate and/or Lauryl Acrylates)

by MD Nahin Islam Shiblee, Kumkum Ahmed, Yuta Yamazaki, Masaru Kawakami and Hidemitsu Furukawa

Polymers 2021, 13(1), 128; https://doi.org/10.3390/polym13010128 - 30 Dec 2020

Cited by 3 | Viewed by 2311

Abstract

In this work, we present the structural analysis of 3D/4D printable N,N-dimethylacrylamide (DMAAm)-co-stearyl acrylate (SA) and/or lauryl acrylate (LA)-based shape memory gels (SMGs). We characterized these gels by scanning microscopic light scattering technique (SMILS) where a time- and space-averaged correlation [...] Read more.

In this work, we present the structural analysis of 3D/4D printable N,N-dimethylacrylamide (DMAAm)-co-stearyl acrylate (SA) and/or lauryl acrylate (LA)-based shape memory gels (SMGs). We characterized these gels by scanning microscopic light scattering technique (SMILS) where a time- and space-averaged correlation function is obtained to overcome the inhomogeneous media. Thus, the characteristic size of the gel internal network (mesh size, ξ) and crosslinking densities are estimated from the Einstein–Stokes formula. The rheological study of the SMGs revealed information about their mechanical strength and transition temperature. From the experimental storage modulus measured by rheological study, crosslinking density and mesh size of the network were also calculated. Both the techniques suggest that SMG with high crystalline content of SA monomer in the gel network contain smaller mesh size (1.13 nm for SMILS and 9.5 nm for rheology study) and high crosslinking density. The comparative study between the light scattering technique and rheological analysis through the quantitative analysis of crosslinking densities will be important to understand the structural properties of the SMGs. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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Review

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48 pages, 13484 KiB

Open AccessReview

Recent Advances in Functional Polymers Containing Coumarin Chromophores

by Ines Cazin, Elisabeth Rossegger, Gema Guedes de la Cruz, Thomas Griesser and Sandra Schlögl

Polymers 2021, 13(1), 56; https://doi.org/10.3390/polym13010056 - 25 Dec 2020

Cited by 33 | Viewed by 8259

Abstract

Natural and synthetic coumarin derivatives have gained increased attention in the design of functional polymers and polymer networks due to their unique optical, biological, and photochemical properties. This review provides a comprehensive overview over recent developments in macromolecular architecture and mainly covers examples [...] Read more.

Natural and synthetic coumarin derivatives have gained increased attention in the design of functional polymers and polymer networks due to their unique optical, biological, and photochemical properties. This review provides a comprehensive overview over recent developments in macromolecular architecture and mainly covers examples from the literature published from 2004 to 2020. Along with a discussion on coumarin and its photochemical properties, we focus on polymers containing coumarin as a nonreactive moiety as well as polymer systems exploiting the dimerization and/or reversible nature of the [2πs + 2πs] cycloaddition reaction. Coumarin moieties undergo a reversible [2πs + 2πs] cycloaddition reaction upon irradiation with specific wavelengths in the UV region, which is applied to impart intrinsic healability, shape-memory, and reversible properties into polymers. In addition, coumarin chromophores are able to dimerize under the exposure to direct sunlight, which is a promising route for the synthesis and cross-linking of polymer systems under “green” and environment-friendly conditions. Along with the chemistry and design of coumarin functional polymers, we highlight various future application fields of coumarin containing polymers involving tissue engineering, drug delivery systems, soft robotics, or 4D printing applications. Full article

(This article belongs to the Special Issue Dynamic Covalent Polymer Networks)

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