Pub Date : 2020-02-27DOI: 10.1088/2399-7532/ab69e2
Isabel P. S. Qamar, N. Sottos, R. Trask
This perspective details the grand challenges of designing and manufacturing multifunctional materials to impart autonomous property recovery. The susceptibility of advanced engineering composites to brittle fracture has led to the emergence of self-healing materials. This functionality has been demonstrated in bulk polymers and fibre-reinforced composites; most recently through the addition of vascular networks into the host material. These network systems enable the healing agents to be transported over long distances and provide a means by which both the resin and hardener can be replenished, thus overcoming the inherent limitations of capsule-based systems. To date, vascule fabrication methods include machining, fugitive scaffold processes, a lost-wax process and the vaporisation of sacrificial components, but recent developments in additive manufacturing (AM) technologies have paved the way for more efficient, bio-inspired vascular designs (VDs) to be realised. This perspective reviews the current progress in vascular self-healing and discusses how AM technologies and new design methods can be exploited in order to fabricate networks that are optimised for fluid transport and structural efficiency. The perspective culminates in the discussion of eight grand challenges across three thematic areas: ‘VD’, ‘Healing Chemistry’ and ‘AM’, that are likely to have major breakthroughs and socio/economic impact as these technologies are developed further in the next 10–15 years.
{"title":"Grand challenges in the design and manufacture of vascular self-healing","authors":"Isabel P. S. Qamar, N. Sottos, R. Trask","doi":"10.1088/2399-7532/ab69e2","DOIUrl":"https://doi.org/10.1088/2399-7532/ab69e2","url":null,"abstract":"This perspective details the grand challenges of designing and manufacturing multifunctional materials to impart autonomous property recovery. The susceptibility of advanced engineering composites to brittle fracture has led to the emergence of self-healing materials. This functionality has been demonstrated in bulk polymers and fibre-reinforced composites; most recently through the addition of vascular networks into the host material. These network systems enable the healing agents to be transported over long distances and provide a means by which both the resin and hardener can be replenished, thus overcoming the inherent limitations of capsule-based systems. To date, vascule fabrication methods include machining, fugitive scaffold processes, a lost-wax process and the vaporisation of sacrificial components, but recent developments in additive manufacturing (AM) technologies have paved the way for more efficient, bio-inspired vascular designs (VDs) to be realised. This perspective reviews the current progress in vascular self-healing and discusses how AM technologies and new design methods can be exploited in order to fabricate networks that are optimised for fluid transport and structural efficiency. The perspective culminates in the discussion of eight grand challenges across three thematic areas: ‘VD’, ‘Healing Chemistry’ and ‘AM’, that are likely to have major breakthroughs and socio/economic impact as these technologies are developed further in the next 10–15 years.","PeriodicalId":18949,"journal":{"name":"Multifunctional Materials","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/2399-7532/ab69e2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46834511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-02-04DOI: 10.1088/2399-7532/ab6d1e
J. Boothby, Tessa Van Volkenburg, N. Le, K. Ohiri, M. Hagedon, Z. Xia
Thermoresponsive liquid crystal elastomers (LCEs) have a high potential to be used for actuation applications. There has been a substantial amount of literature on synthesis of different LCE networks and their corresponding performance. However, much of the prior work focuses on the experimental aspect of the effects of mesogenic species, crosslinkers, and spacers on the thermal and mechanical response of LCE. Here we have built on these prior studies, and expanded understanding of LCE work capacity and thermal properties to the molecular and network structures by comparing the experimental results to the theoretically predicted values based on a random walk model derived from classical rubber elasticity. A previously developed two stage thiol-acrylate LCE chemistry was used as the model system. On the basis of increasing the chain entropy, we varied crosslinker concentration, crosslinker functionality, and liquid crystal mesogen length and showed that average molecular weight between crosslinks and molecular weight of the Kuhn segment play important roles in controlling the work capacity. The rubber elastic model predicted network performance agreed reasonably well with the experimental results.
{"title":"Effects of network structure on the mechanical and thermal responses of liquid crystal elastomers","authors":"J. Boothby, Tessa Van Volkenburg, N. Le, K. Ohiri, M. Hagedon, Z. Xia","doi":"10.1088/2399-7532/ab6d1e","DOIUrl":"https://doi.org/10.1088/2399-7532/ab6d1e","url":null,"abstract":"Thermoresponsive liquid crystal elastomers (LCEs) have a high potential to be used for actuation applications. There has been a substantial amount of literature on synthesis of different LCE networks and their corresponding performance. However, much of the prior work focuses on the experimental aspect of the effects of mesogenic species, crosslinkers, and spacers on the thermal and mechanical response of LCE. Here we have built on these prior studies, and expanded understanding of LCE work capacity and thermal properties to the molecular and network structures by comparing the experimental results to the theoretically predicted values based on a random walk model derived from classical rubber elasticity. A previously developed two stage thiol-acrylate LCE chemistry was used as the model system. On the basis of increasing the chain entropy, we varied crosslinker concentration, crosslinker functionality, and liquid crystal mesogen length and showed that average molecular weight between crosslinks and molecular weight of the Kuhn segment play important roles in controlling the work capacity. The rubber elastic model predicted network performance agreed reasonably well with the experimental results.","PeriodicalId":18949,"journal":{"name":"Multifunctional Materials","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/2399-7532/ab6d1e","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42825002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-27DOI: 10.1088/2399-7532/ab686d
Moumita Rana, Y. Ou, Chenchen Meng, F. Sket, C. González, J. Vilatela
A natural embodiment for multifunctional materials combining energy-storing capabilities and structural mechanical properties are layered structures, similar to both laminate structural composites and electrochemical energy-storage devices. A structural composite with integrated electric double layer capacitive storage is produced by resin infusion of a lay up including woven glass fabric used as mechanical reinforcement, carbon nanotube non-woven fabrics as electrodes/current collectors and a polymer electrolyte. The energy-storing layer is patterned with holes, which after integration form resin plugs for mechanical interconnection between layers, similar to rivets. Finite element modelling is used to optimise rivet shape and areal density on interlaminar shear properties. Galvanostatic charge-discharge tests during three-point bending show no degradation of properties after large deflections or repeated load/unload cycling at 3.5 V. This mechanical tolerance is a consequence of the elimination of metallic current collectors and the effective integration of multifunctional materials, as observed by electron microscopy and x-ray computed tomography. In contrast, control samples with metallic current collectors, analogous to embedded devices, rapidly degrade upon repeated bending.
{"title":"Damage-tolerant, laminated structural supercapacitor composites enabled by integration of carbon nanotube fibres","authors":"Moumita Rana, Y. Ou, Chenchen Meng, F. Sket, C. González, J. Vilatela","doi":"10.1088/2399-7532/ab686d","DOIUrl":"https://doi.org/10.1088/2399-7532/ab686d","url":null,"abstract":"A natural embodiment for multifunctional materials combining energy-storing capabilities and structural mechanical properties are layered structures, similar to both laminate structural composites and electrochemical energy-storage devices. A structural composite with integrated electric double layer capacitive storage is produced by resin infusion of a lay up including woven glass fabric used as mechanical reinforcement, carbon nanotube non-woven fabrics as electrodes/current collectors and a polymer electrolyte. The energy-storing layer is patterned with holes, which after integration form resin plugs for mechanical interconnection between layers, similar to rivets. Finite element modelling is used to optimise rivet shape and areal density on interlaminar shear properties. Galvanostatic charge-discharge tests during three-point bending show no degradation of properties after large deflections or repeated load/unload cycling at 3.5 V. This mechanical tolerance is a consequence of the elimination of metallic current collectors and the effective integration of multifunctional materials, as observed by electron microscopy and x-ray computed tomography. In contrast, control samples with metallic current collectors, analogous to embedded devices, rapidly degrade upon repeated bending.","PeriodicalId":18949,"journal":{"name":"Multifunctional Materials","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/2399-7532/ab686d","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45577822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-21DOI: 10.1088/2399-7532/ab54ea
Beijun Shen, O. Erol, Lichen Fang, S. Kang
3D printing technology has revolutionized various fields since it was first developed in the 1980s. In 2013, time was introduced to the spatial dimensions of the 3D printing as a new dimension leading to 4D printing. This emerging technology integrates stimuli-responsive materials with 3D printing technologies and opened up new possibilities for challenging problems by allowing the fabrication of complex structures that can undergo programmed temporal changes in response to external stimuli. Despite extensive research on advanced materials and printing techniques, the programming pathways of time into the structures and materials are still in the early stages. In this review, we comprehensively reviewed the potential programming routes of time utilized in 4D printing. These programming routes were identified and classified into three main approaches based on the timing of the programming during the 4D printing processes. These categories are designated as pre-, peri- and post-printing approaches. Then, these main categories were further expanded based on the methods employed during 4D printing to achieve temporal changes. We have also classified the computational tools used to design, program, and fabricate 4D printed structures, specifically focusing on materials modeling and structural design approaches. Finally, we have discussed the current challenges and roadblocks that need to be overcome within 4D printing frameworks to make 4D printing a highly accessible technology.
{"title":"Programming the time into 3D printing: current advances and future directions in 4D printing","authors":"Beijun Shen, O. Erol, Lichen Fang, S. Kang","doi":"10.1088/2399-7532/ab54ea","DOIUrl":"https://doi.org/10.1088/2399-7532/ab54ea","url":null,"abstract":"3D printing technology has revolutionized various fields since it was first developed in the 1980s. In 2013, time was introduced to the spatial dimensions of the 3D printing as a new dimension leading to 4D printing. This emerging technology integrates stimuli-responsive materials with 3D printing technologies and opened up new possibilities for challenging problems by allowing the fabrication of complex structures that can undergo programmed temporal changes in response to external stimuli. Despite extensive research on advanced materials and printing techniques, the programming pathways of time into the structures and materials are still in the early stages. In this review, we comprehensively reviewed the potential programming routes of time utilized in 4D printing. These programming routes were identified and classified into three main approaches based on the timing of the programming during the 4D printing processes. These categories are designated as pre-, peri- and post-printing approaches. Then, these main categories were further expanded based on the methods employed during 4D printing to achieve temporal changes. We have also classified the computational tools used to design, program, and fabricate 4D printed structures, specifically focusing on materials modeling and structural design approaches. Finally, we have discussed the current challenges and roadblocks that need to be overcome within 4D printing frameworks to make 4D printing a highly accessible technology.","PeriodicalId":18949,"journal":{"name":"Multifunctional Materials","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/2399-7532/ab54ea","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45078450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-31DOI: 10.1088/2399-7532/ab4f9d
T. Calais, P. Valdivia y Alvarado
Reversibility, a key property in materials science and soft matter, is extremely desirable to enable advanced functionality in soft robots. So far, tunable rigidity has attracted most of the attention, notably for its application in novel soft actuators, soft grippers, and its potential impact in locomotion of soft and hybrid robotic devices. Herein, we review recent progress on reversibility in other physicochemical properties which can also play important roles in the functionality of soft robots. We focus on the tunability of five key properties: electrical and thermal conductivities, surface wettability and adhesion, and optical properties. Materials and mechanisms are described, and performances are assessed, when possible, in terms of reversible tunability range, time response, cycling endurance, and power consumption. The potential integration of such solutions to soft robots is systematically discussed.
{"title":"Advanced functional materials for soft robotics: tuning physicochemical properties beyond rigidity control","authors":"T. Calais, P. Valdivia y Alvarado","doi":"10.1088/2399-7532/ab4f9d","DOIUrl":"https://doi.org/10.1088/2399-7532/ab4f9d","url":null,"abstract":"Reversibility, a key property in materials science and soft matter, is extremely desirable to enable advanced functionality in soft robots. So far, tunable rigidity has attracted most of the attention, notably for its application in novel soft actuators, soft grippers, and its potential impact in locomotion of soft and hybrid robotic devices. Herein, we review recent progress on reversibility in other physicochemical properties which can also play important roles in the functionality of soft robots. We focus on the tunability of five key properties: electrical and thermal conductivities, surface wettability and adhesion, and optical properties. Materials and mechanisms are described, and performances are assessed, when possible, in terms of reversible tunability range, time response, cycling endurance, and power consumption. The potential integration of such solutions to soft robots is systematically discussed.","PeriodicalId":18949,"journal":{"name":"Multifunctional Materials","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/2399-7532/ab4f9d","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48262606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}