Abstract
Polyvinyl alcohol (PVA)-based magnetorheological plastomer (MRP) possesses excellent magnetically dependent mechanical properties such as the magnetorheological effect (MR effect) when exposed to an external magnetic field. PVA-based MRP also shows a shear stiffening (ST) effect, which is very beneficial in fabricating pressure sensor. Thus, it can automatically respond to external stimuli such as shear force without the magnetic field. The dual properties of PVA-based MRP mainly on the ST and MR effect are rarely reported. Therefore, this work empirically investigates the dual properties of this smart material under the influence of different solvent compositions (20:80, 40:60, 60:40, and 80:20) by varying the ratios of binary solvent mixture (dimethyl sulfoxide (DMSO) to water). Upon applying a shear stress with excitation frequencies from 0.01 to 10 Hz, the storage modulus (G′) for PVA-based MRP with DMSO to water ratio of 20:40 increases from 6.62 × 10−5 to 0.035 MPa. This result demonstrates an excellent ST effect with the relative shear stiffening effect (RSTE) up to 52,827%. In addition, both the ST and MR effect show a downward trend with increasing DMSO content to water. Notably, the physical state of hydrogel MRP could be changed with different solvent ratios either in the liquid-like or solid-like state. On the other hand, a transient stepwise experiment showed that the solvent’s composition had a positive effect on the arrangement of CIPs within the matrix as a function of the external magnetic field. Therefore, the solvent ratio (DMSO/water) can influence both ST and MR effects of hydrogel MRP, which need to be emphasized in the fabrication of hydrogel MRP for appropriate applications primarily with soft sensors and actuators for dynamic motion control.
Highlights
Licensee MDPI, Basel, Switzerland.Sensors are small machines or devices purposely employed to detect changes in their environment by changing the information received from other electronics, usually a computer processor
The materials used to fabricate this sensor must be soft, flexible, stretchable, and humanfriendly with high sensitivity and flexibility. Soft materials such as hydrogel have been widely used in the fabrication of wearable strain or piezo resistance sensors due to their soft, hydrophilic nature, high stretchability and biocompatibility [8,9,10]
dimethyl sulfoxide sulfoxide (DMSO) brand ChemAR was supplied by Systerm Chemicals and deionized water was used as a solvent
Summary
Licensee MDPI, Basel, Switzerland.Sensors are small machines or devices purposely employed to detect changes in their environment by changing the information received from other electronics, usually a computer processor. Widely used in electronic devices such as wearable skin-electronic devices to detect and predict human motion, thought and activities [3,4,5,6]. In wearable skin-electronic devices, a pressure signal is frequently utilized to relay human action to the device [7]. The materials used to fabricate this sensor must be soft, flexible, stretchable, and humanfriendly with high sensitivity and flexibility. Soft materials such as hydrogel have been widely used in the fabrication of wearable strain or piezo resistance sensors due to their soft, hydrophilic nature, high stretchability and biocompatibility [8,9,10]
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