Highly Dielectric Rubber Bearing Cyanoethyl Group with Various Side-Chain Structures

Abstract

We synthesized rubbers including cyanoethyl groups and evaluated the effect of side-chain structures on dielectric properties, electrical properties at room temperature, and glass-transition temperatures (T g). New monomers including cyanoethyl were synthesized via the thiol–ene reaction and esterification; these included 3-((2,4-dicyanobutyl)­thio)­propyl acrylate (DCEA3M) and 6-((2,4-dicyanobutyl)­thio)­hexyl acrylate (DCEA6M). Copolymers consisting of 2-cyanoethyl acrylate (CEA) and DCEA3M or DCEA6M were synthesized to obtain a rubber with a high dielectric constant. Reference copolymer samples with varying CN wt % consisted of CEA and acrylate monomers were also synthesized. Undesirable gelation occurred during polymerization of monomers including cyanoethyl; however, gelation could be resolved by changing the monomer concentration and reaction time. The copolymers exhibited a T g of 5 °C or below, and the relative dielectric constant at 100 Hz was above 10. pDCEA3M exhibited the highest dielectric constant of 20.3 corresponding to a high CN wt % of 20.6%, and pDCEA6M displayed the lowest T g of −33.2 °C due to the internal plasticization corresponding to the long side chain; however, the dielectric losses of pDCEA3M and pDCEA6M were as high as 3.2 and 7.7, respectively. On the other hand, p­(CEA–DCEA3M) and p­(CEA–DCEA6M) copolymerized with CEA could reduce the dielectric loss (∼2.4) while maintaining high dielectric constant (16.3–18.9) and low T g (−22.9––3.36 °C). The copolymers also exhibited a high dielectric constant at a comparable volume resistivity (1010–1012 Ω·cm) compared to commercial rubbers. Such elastomers with high dielectric constant and low dielectric loss are expected to improve the performance of soft actuators.

Polysiloxanes Modified with Different Types and Contents of Polar Groups: Synthesis, Structure, and Thermal and Dielectric Properties

“…A similar behavior was recently reported for some nitrile-modified acrylates. 52 The impact the volume of the polar groups has on T g and dielectric permittivity can be observed when comparing the dielectric properties of polymers modified with 6 and 12. PM 8 V 2 -6 and PM 8 V 2 -12 have a low content of polar groups and thus the dipole−dipole interactions remain weak at this dipole concentration.…”

“…The low T g can probably be attributed to the longer −(CH 2 ) 2 –S–(CH 2 ) 2 –S linker in the case of thiol 7 compared to the shorter −(CH 2 ) 2 –S– linker in 6 . A similar behavior was recently reported for some nitrile-modified acrylates …”

Eliminating the Misconceptions Regarding the Usage of Commercially Available Silicone Elastomers in Thin Film Actuators

“…[23] It is well known that PDMS does not necessarily offer either a high or low value of ε' 0 (=≈2.8) at room temperature over the frequency range of general interest for the DEA applications among polymeric materials. [24] One popular research topic associated with PDMS DEs is thus to devise a new approach that allows for increasing the value of ε 0 while leading to a reduction in V. The same strategy has been adopted for organic competitive DEs, such as polyacrylates [25] and polyrotaxanes, [26] which are also commonly used in the DE field. For PDMS, various inorganic filler particles with different chemical compositions and shapes have been examined and characterized in terms of mechanical and chemical resistance properties.…”

Phase‐Separated Dielectric Gels Based on Christiansen Effect

“…The two typical characteristics of polymer dielectric elastomers includes flexibility [20,21] and ultra-high dielectric constant to be driven by an electric field necessarily. [22][23][24][25][26] Soft and deformable characteristics provide the possibility for the emergence of flexible electronic products such as soft robots. [11,27,28] However, the compatibility difference of each component causes the phase separation happening in polymer synthesis.…”