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Shape Memory Polymers
Published in Asit Baran Samui, Smart Polymers, 2022
While considering the plasticity of thermosets, the idea of a vitrimer has appeared. Vitrimers, derived from thermosets, are able to reform their covalent polymer networks while specific conditions are maintained. Bond exchange reactions, such as transesterification reactions or dynamic covalent bond formation and breaking, are the routes to restrict the network.19 Most of the vitrimers or vitrimer-like materials are generally reprocessed via heating to a high temperature or by light irradiation. The reprocessing of the vitrimer-like materials is mainly based on the photochemical reactions or disulfide bond exchanges that require ultraviolet (UV) light.20 The UV light is likely to damage the polymer chains, resulting in deterioration of their mechanical properties and lifetimes. The penetration power of UV light is limited, for example, below 300 nm. Therefore, the UV light becomes partially effective for polymers, such as for some PUs, even those with 1 mm thickness. Spatial and temporal control and cost-effectiveness are the advantages of using visible light, together with its non-damaging nature on the polymer chains. The exchange reactions via dynamic covalent diselenide bonds are triggered by visible light.21 The introduction of diselenide bonds into the polymeric architecture, such as PUs, enables it to undergo polymer chain reformation under visible light, leading to self-healing. The loaded stress can be relaxed during the chain reformation through the whole material that indicates that the material can be reprocessed (Figure 10.6).
Renewable Vitrimer—A Novel Route Towards Reprocessable and Recyclable Thermosets from Biomass-Derived Building Block
Published in Anandhan Srinivasan, Selvakumar Murugesan, Arunjunai Raj Mahendran, Progress in Polymer Research for Biomedical, Energy and Specialty Applications, 2023
Arunjunai Raj Mahendran, Mohammed Khalifa, Günter Wuzella, Herfried Lammer
The low viscosity of the uncured resin permits uniform flow to integrate with reinforced fibers, indicating that the vitrimer resins can also be made in the form of prepregs. However, vitrimer prepregs are cured instantaneously after the infusion. Several studies have indicated that the recycling of vitrimer composite does not damage the fibers with excellent recovery efficiency without losing the mechanical properties. Hence, in applications such as sports equipment, wind energy, automobiles, pressure vessels, and coating industries, vitrimers can make a tremendous impact.
Application of butane-1,4-diyl bis(2-mercaptoacetate) as dithiol prepolymer for preparation of polythiourethane and clay-based nanocomposites
Published in Journal of Sulfur Chemistry, 2022
Amin Pirayesh, Nazanin Qolizade, Saeid Talebi, Mehdi Salami-Kalajahi
Butane-1,4-diyl bis(2-mercaptoacetate) (BBMA) or 1,4-butanediol bis(thioglycolate) as a dithiol compound has been used as a thiol compound in thiol–ene click reactions [26,27] and in the synthesis of epoxy-based vitrimers via the transesterification reaction [28]. Also, it has been used as a chain extender in the synthesis of hyperbranched PTUs [29]. In this work, we have synthesized butane-1,4-diyl bis(2-mercaptoacetate) (BBMA) as a dithiol compound via the esterification of 1,4-butanediol and thioglycolic acid. BBMA as a prepolymer has been reacted with 4,4'-diphenylmethane diisocyanate (MDI) to prepare poly(thiourethane). Moreover, Cloisite 30B (1–5 wt.%) has been used to prepare clay/poly(thiourethane) nanocomposites. Finally, the effect of Cloisite 30B content on structural, thermophysical, and thermal properties of nanocomposites has been investigated.
Recycling strategies for vitrimers
Published in International Journal of Smart and Nano Materials, 2022
Haochuan Zhang, Jingjing Cui, Guang Hu, Biao Zhang
In this review, we briefly summarize the definition and characteristics of vitrimers in nature and then emphasize the recycling strategies of vitrimers in details from both physical and chemical recycling methods. Importantly, we compare the advantages and disadvantages of the two different recycling strategies. The physical recycling method is simple but low-efficient and energy-consuming, while the chemical recycling method is high-yielding but time-consuming. In addition, with the advent of vitrimers, the variety and integrity of material systems for 3D printing have also been achieved. The introduction of special structures in vitrimers has increased the recycling time and profitability of 3D printing materials to a higher level. It means that vitrimers provide a highly viable solution to the recyclable problem of 3D printing materials. The benefits of working with raw materials for 3D printing have been expanded. However, there are too few vitrimer materials available for 3D printing. And there are still many issues that need to be addressed for commercializing the vitrimer materials in 3D printing, such as cost reduction, efficiency and sustainability. It is expected that more recyclable vitrimer materials will be developed to replace traditional disposable printing materials, so that the pollution problems of consumables from a large amount of use of 3D printing materials could be solved efficiently, thereby providing a sustainable strategy for realizing the vision of ‘emission peak and carbon neutrality.