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Integrated Bending Actuation and the Self‐Sensing Capability of Poly(Vinyl Chloride) Gels with Ionic Liquids

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Soft actuation materials often only perform an actuation function, and do not achieve the function of self‐sensing. In this work, the polyvinyl chloride (PVC) gels are prepared with a plasticizer of dibutyl adipate (DBA) and small amount of imidazolium type ionic liquids (ILs), and are demonstrated that the PVC/DBA/ILs gels deliver the integrated bending actuation and capacitance pressure self‐sensing capability. The bending actuation performances and sensing behavior of PVC/DBA/ILs are related to the migrability of movable ions from ILs, which are dependent on the dissociation of anions and cations of ILs, and the concentration of ILs. Among the ILs, the PVC/DBA gel with 3.3 wt% 1‐allyl‐3‐methylimidazolium bis ((trifluoromethyl)sulphonyl) imide (P/[AMIM]NTF2 (3.3 wt%)) exhibits best bending displacement of 6.6 mm (corresponding to 24° of bending angle) at 7.2 kV (180 V mm⁻¹ of nominal electric field). In addition, the P/[AMIM]NTF2 (3.3 wt%) exhibits 0.42 kPa–1 capacitance pressure sensitive in the pressure range 0 to 2.2 kPa, and a sudden change in capacitance in the pressure range 2.2–2.7 kPa with 47.5 kPa–1 of sensitivity. The results can provide a new idea for developing integrated sensing and actuation functions of electroactive dielectric polymer gels.
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2204259 (1 of 11)
Integrated Bending Actuation and the Self-Sensing
Capability of Poly(Vinyl Chloride) Gels with Ionic Liquids
Zhiwei Liu, Beibei Li, Ying Dan Liu,* and Yongri Liang*
Soft actuation materials often only perform an actuation function, and do not
achieve the function of self-sensing. In this work, the polyvinyl chloride (PVC)
gels are prepared with a plasticizer of dibutyl adipate (DBA) and small amount
of imidazolium type ionic liquids (ILs), and are demonstrated that the PVC/
DBA/ILs gels deliver the integrated bending actuation and capacitance pres-
sure self-sensing capability. The bending actuation performances and sensing
behavior of PVC/DBA/ILs are related to the migrability of movable ions from
ILs, which are dependent on the dissociation of anions and cations of ILs, and
the concentration of ILs. Among the ILs, the PVC/DBA gel with 3.3 wt% 1-allyl-
3-methylimidazolium bis ((trifluoromethyl)sulphonyl) imide (P/[AMIM]NTF2
(3.3 wt%)) exhibits best bending displacement of 6.6mm (corresponding to
24° of bending angle) at 7.2kV (180V mm1 of nominal electric field). In addi-
tion, the P/[AMIM]NTF2 (3.3 wt%) exhibits 0.42 kPa–1 capacitance pressure
sensitive in the pressure range 0 to 2.2kPa, and a sudden change in capaci-
tance in the pressure range 2.2–2.7kPa with 47.5 kPa–1 of sensitivity. The
results can provide a new idea for developing integrated sensing and actuation
functions of electroactive dielectric polymer gels.
DOI: 10.1002/adfm.202204259
Z. Liu, B. Li, Y. D. Liu, Y. Liang
State Key Lab of Metastable Materials Science and Technology,
and School of Materials Science and Engineering
Yanshan University
No. 438 West Hebei Avenue, Qinhuangdao, Hebei 0066004, P.R. China
E-mail: ydliu@ysu.edu.cn; liangyr@ysu.edu.cn
conductivity of elastomers are usually ben-
eficial for improving pressure-sensing per-
formance,[12,13] however are unfavorable
for improving actuation performances.[14]
The dielectric polymer gel (DPG) is an
electronic type of electroactive elastomers
which has many advantages than dielectric
elastomers due to low modulus and high
dielectrics such as lower driving voltage,
degree of various actuation freedoms and
high actuation strain etc.[15] The polyvinyl
chloride (PVC) gel[16,17] is the most inves-
tigated DPG. The PVC gels as actuators or
artificial muscles have shown a significant
potential for ecient applications due to
the easily available, low-cost, and electri-
cally inactive PVC. For example, Hirai
et al.[18] first found that PVC gels with
90 wt% of dioctyl phthalate (DOP) could
perform crawling motion under an applied
DC electric field. Thereafter, the bending
deformation and amoeba-like creep defor-
mation behaviors of PVC gels have been
widely investigated.[19,20] Hirai etal.[21] considered that the elec-
tron injection induces plasticizer dragging to the anode when
applied the electric field to the electrodes sandwiching the
PVC gel, and then forming a space charge layer (i.e., solvent-
rich layer, S-R layer) near the anode.[22] The electric interfacial
adhesive force between the space charge layer and anode causes
the creep motion of the PVC gel.[20] Asaka and Hashimoto[17]
developed the electromechanical model of PVC/dibutyl adipate
(DBA) gel-based on electromechanical modeling. They pro-
posed that when a voltage is applied to the PVC gel, fluxes of a
plasticizer are dragged with the anion current to the anode side.
Then, much thinner than the PVC bulk layer of the S-R layer
formed on the anode surface as anions are discharged at the
anode. The deformation of the S-R layer by the Maxwell stress
gives the bending motion of PVC gel film. However, the capa-
bility of integrated actuation and self-sensing of PVC gels has
not been well demonstrated so far.
Here, we reported that the PVC gel with ionic liquid (IL) can
be used as self-sensing actuators to ensure the safety and reli-
ability of the system based on the feedback of self-perceived a
certain pressure. (Figure 1e) The PVC gels were prepared by
solution casting method using dibutyl adipate (DBA) of plas-
ticizer and 1-allyl-3-methylimidazolium based ILs (Figure 1a).
The bending actuation of PVC gels with free electrodes was
investigated by home-built bending displacement measurement
system. (Figure1b) Among the imidazolium type ILs, the PVC/
DBA with 1-allyl-3-methylimidazolium bis((trifluoromethyl)
sulphonyl) imide ([AMIM]NTF2) exhibited 6.6mm of bending
ReseaRch aRticle
The ORCID identification number(s) for the author(s) of this article
can be found under https://doi.org/10.1002/adfm.202204259.
1. Introduction
Biological systems have exhibited as integration of sensing,
actuation, and computation functions, such as self-achieve
shape and appearance changes, self-adaptive load support
etc.[1,2] Such integration of sensing, actuation, and computa-
tion of smart materials have wide potential applications in air-
craft, vehicles, sensorial robotics, prosthetics, and clothing and
furniture.[3]
Electroactive polymers (EAPs) are promising smart materials
that can change their shape or size under electric fields, or con-
versely, can generate electric charges under pressure.[4,5] Even
though some integration of actuation and sensing has been
achieved in the dielectric elastomer[6–9] and piezoelectric mate-
rials,[10,11] the development of EAPs with integration of actua-
tion and sensing still have a big challenge for simultaneously
achieving high-pressure sensitivity and high actuation perfor-
mances. For example, the strategies of improving elastomers
Adv. Funct. Mater. 2022, 32, 2204259
... The vibration bands positions shifted more with the increase in IL concentration, which reflected the strong interaction between Eu (NO 3 ) 3 ·6H 2 O and IL. From Figure 5b, we can see that a strong vibration band appeared at 1562cm −1 , which was attributed to the stretching vibration of the imidazole ring of ILs [33]. With the increase in IL concentration, the vibration bands intensity gradually increased. ...
... The vibration bands positions shifted more with the increase in IL concentration, which reflected the strong interaction between Eu (NO3)3·6H2O and IL. From Figure 5b, we can see that a strong vibration band appeared at 1562cm −1 , which was attributed to the stretching vibration of the imidazole ring of ILs [33]. With the increase in IL concentration, the vibration bands intensity gradually increased. ...
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