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Magnetic Field Triggered Multicycle Damage Sensing and Self Healing.

Ahmed AS, Ramanujan RV - Sci Rep (2015)

Bottom Line: Magpol exhibited a linear strain response upto 150% strain and complete recovery after healing.We have demonstrated the use of this concept in a reusable biomedical device i.e., coated guidewires.Our findings offer a new synergistic method to bestow multifunctionality for applications ranging from medical device coatings to adaptive wing structures.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore.

ABSTRACT
Multifunctional materials inspired by biological structures have attracted great interest, e.g. for wearable/ flexible "skin" and smart coatings. A current challenge in this area is to develop an artificial material which mimics biological skin by simultaneously displaying color change on damage as well as self healing of the damaged region. Here we report, for the first time, the development of a damage sensing and self healing magnet-polymer composite (Magpol), which actively responds to an external magnetic field. We incorporated reversible sensing using mechanochromic molecules in a shape memory thermoplastic matrix. Exposure to an alternating magnetic field (AMF) triggers shape recovery and facilitates damage repair. Magpol exhibited a linear strain response upto 150% strain and complete recovery after healing. We have demonstrated the use of this concept in a reusable biomedical device i.e., coated guidewires. Our findings offer a new synergistic method to bestow multifunctionality for applications ranging from medical device coatings to adaptive wing structures.

No MeSH data available.


Related in: MedlinePlus

Schematic of damage sensing and self healing in Magpol.The sample displays damage sensing by a colour change on plastic deformation. This colour change becomes more pronounced with increasing strain. The sample is strained until failure. Subsequently, healing is carried out in an AMF. Embedded nanoparticles generate heat, resulting in recovery of the original shape and healing of the damaged region along with a return to the original colour.
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f1: Schematic of damage sensing and self healing in Magpol.The sample displays damage sensing by a colour change on plastic deformation. This colour change becomes more pronounced with increasing strain. The sample is strained until failure. Subsequently, healing is carried out in an AMF. Embedded nanoparticles generate heat, resulting in recovery of the original shape and healing of the damaged region along with a return to the original colour.

Mentions: Figure 1 is a schematic of the strain sensing and triggered healing of Magpol. Plastic deformation causes color change from greenish blue to deep blue due to disaggregation of the bis(benzoxazolyl)stilbene (BBS) chromophore. Further deformation ultimately leads to failure. Following failure, the two pieces of Magpol are placed in contact and exposed to an external radio frequency alternating magnetic field (AMF). The magnetic nanoparticles generate heat due to Néel relaxation losses which is transferred to the surrounding shape memory polymer matrix (poly ethylene –co- vinyl acetate EVA). The Mn Zn ferrite nanoparticles used in this study have a Curie temperature of 230°C which is below the temperature at which EVA undergoes pyrolysis, thus ensuring the stability of the system45. The resulting temperature rise triggers recovery of the original component shape and the original chromophore aggregate structures. This is followed by polymer chain entanglement at the failure interface of the two pieces; leading to healing. The advantage of using magnetically triggered heating is that heating can be remotely triggered at high penetration depth. Secondly, chromophore aggregates on the surface of Magpol are at relatively lower temperatures due to heat loss to the surroundings, preventing their disaggregation. The interface to be healed can, in the meanwhile, achieve the higher temperature required for polymer chain movement, ensuring efficient healing.


Magnetic Field Triggered Multicycle Damage Sensing and Self Healing.

Ahmed AS, Ramanujan RV - Sci Rep (2015)

Schematic of damage sensing and self healing in Magpol.The sample displays damage sensing by a colour change on plastic deformation. This colour change becomes more pronounced with increasing strain. The sample is strained until failure. Subsequently, healing is carried out in an AMF. Embedded nanoparticles generate heat, resulting in recovery of the original shape and healing of the damaged region along with a return to the original colour.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562241&req=5

f1: Schematic of damage sensing and self healing in Magpol.The sample displays damage sensing by a colour change on plastic deformation. This colour change becomes more pronounced with increasing strain. The sample is strained until failure. Subsequently, healing is carried out in an AMF. Embedded nanoparticles generate heat, resulting in recovery of the original shape and healing of the damaged region along with a return to the original colour.
Mentions: Figure 1 is a schematic of the strain sensing and triggered healing of Magpol. Plastic deformation causes color change from greenish blue to deep blue due to disaggregation of the bis(benzoxazolyl)stilbene (BBS) chromophore. Further deformation ultimately leads to failure. Following failure, the two pieces of Magpol are placed in contact and exposed to an external radio frequency alternating magnetic field (AMF). The magnetic nanoparticles generate heat due to Néel relaxation losses which is transferred to the surrounding shape memory polymer matrix (poly ethylene –co- vinyl acetate EVA). The Mn Zn ferrite nanoparticles used in this study have a Curie temperature of 230°C which is below the temperature at which EVA undergoes pyrolysis, thus ensuring the stability of the system45. The resulting temperature rise triggers recovery of the original component shape and the original chromophore aggregate structures. This is followed by polymer chain entanglement at the failure interface of the two pieces; leading to healing. The advantage of using magnetically triggered heating is that heating can be remotely triggered at high penetration depth. Secondly, chromophore aggregates on the surface of Magpol are at relatively lower temperatures due to heat loss to the surroundings, preventing their disaggregation. The interface to be healed can, in the meanwhile, achieve the higher temperature required for polymer chain movement, ensuring efficient healing.

Bottom Line: Magpol exhibited a linear strain response upto 150% strain and complete recovery after healing.We have demonstrated the use of this concept in a reusable biomedical device i.e., coated guidewires.Our findings offer a new synergistic method to bestow multifunctionality for applications ranging from medical device coatings to adaptive wing structures.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore.

ABSTRACT
Multifunctional materials inspired by biological structures have attracted great interest, e.g. for wearable/ flexible "skin" and smart coatings. A current challenge in this area is to develop an artificial material which mimics biological skin by simultaneously displaying color change on damage as well as self healing of the damaged region. Here we report, for the first time, the development of a damage sensing and self healing magnet-polymer composite (Magpol), which actively responds to an external magnetic field. We incorporated reversible sensing using mechanochromic molecules in a shape memory thermoplastic matrix. Exposure to an alternating magnetic field (AMF) triggers shape recovery and facilitates damage repair. Magpol exhibited a linear strain response upto 150% strain and complete recovery after healing. We have demonstrated the use of this concept in a reusable biomedical device i.e., coated guidewires. Our findings offer a new synergistic method to bestow multifunctionality for applications ranging from medical device coatings to adaptive wing structures.

No MeSH data available.


Related in: MedlinePlus