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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

Self healing properties of Magpol.(A) i: Sample is strained until failure and exhibits large plastic before failure. ii: After exposure to an AMF for 30 s, the sample shows shape recovery of the plastically deformed regions without joining of the two halves. iii: Further exposure to the AMF for 20 minutes resulted in healing at the damaged interface. (B) PL spectra of Magpol shows the change in the IE intensity (at 515 nm) before and after damage as well as after healing. (C) Mechanical properties after healing: Loads/extension curves of Magpol, until failure, healed and measured again until failure.
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f5: Self healing properties of Magpol.(A) i: Sample is strained until failure and exhibits large plastic before failure. ii: After exposure to an AMF for 30 s, the sample shows shape recovery of the plastically deformed regions without joining of the two halves. iii: Further exposure to the AMF for 20 minutes resulted in healing at the damaged interface. (B) PL spectra of Magpol shows the change in the IE intensity (at 515 nm) before and after damage as well as after healing. (C) Mechanical properties after healing: Loads/extension curves of Magpol, until failure, healed and measured again until failure.

Mentions: Healing of Magpol occurs in two steps, (a) shape recovery which restores the original sample dimensions. This step reverses the plastic deformation that has occurred before failure, resulting in two pieces with a defined edge (Fig. 5(A ii)). During this process, the original chromophore aggregates are reformed, resulting in the recovery of the original colour (Fig. 5(B)). The fluorescence intensity of the chromophore aggregates in the recovered sample is not equal to the original, but substantial restoration is still observed which is sufficient to cause a colour change. (b) the two halves are then held together in an AMF for 10 min. to achieve complete healing at the interface (Fig. 5(A iii)). Healing is achieved through entanglement of polymer chains along the interface. Figure 5 shows the recovery of mechanical properties of Magpol after failure. The yield stress is lower in the recovered sample, possibly due to lower crystalline content (consistent with the DSC and XRD analysis: Supplementary information). Crystallites can act as fillers and as cross-links which are not completely recovered after failure. Multiple cycles of self healing have been studied in our previous work45.


Magnetic Field Triggered Multicycle Damage Sensing and Self Healing.

Ahmed AS, Ramanujan RV - Sci Rep (2015)

Self healing properties of Magpol.(A) i: Sample is strained until failure and exhibits large plastic before failure. ii: After exposure to an AMF for 30 s, the sample shows shape recovery of the plastically deformed regions without joining of the two halves. iii: Further exposure to the AMF for 20 minutes resulted in healing at the damaged interface. (B) PL spectra of Magpol shows the change in the IE intensity (at 515 nm) before and after damage as well as after healing. (C) Mechanical properties after healing: Loads/extension curves of Magpol, until failure, healed and measured again until failure.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Self healing properties of Magpol.(A) i: Sample is strained until failure and exhibits large plastic before failure. ii: After exposure to an AMF for 30 s, the sample shows shape recovery of the plastically deformed regions without joining of the two halves. iii: Further exposure to the AMF for 20 minutes resulted in healing at the damaged interface. (B) PL spectra of Magpol shows the change in the IE intensity (at 515 nm) before and after damage as well as after healing. (C) Mechanical properties after healing: Loads/extension curves of Magpol, until failure, healed and measured again until failure.
Mentions: Healing of Magpol occurs in two steps, (a) shape recovery which restores the original sample dimensions. This step reverses the plastic deformation that has occurred before failure, resulting in two pieces with a defined edge (Fig. 5(A ii)). During this process, the original chromophore aggregates are reformed, resulting in the recovery of the original colour (Fig. 5(B)). The fluorescence intensity of the chromophore aggregates in the recovered sample is not equal to the original, but substantial restoration is still observed which is sufficient to cause a colour change. (b) the two halves are then held together in an AMF for 10 min. to achieve complete healing at the interface (Fig. 5(A iii)). Healing is achieved through entanglement of polymer chains along the interface. Figure 5 shows the recovery of mechanical properties of Magpol after failure. The yield stress is lower in the recovered sample, possibly due to lower crystalline content (consistent with the DSC and XRD analysis: Supplementary information). Crystallites can act as fillers and as cross-links which are not completely recovered after failure. Multiple cycles of self healing have been studied in our previous work45.

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