Electrochimica Acta, Volume 108, 2013, Pages 547-553.
Suran Kim, Seungbum Hong, Yoon-Young Choi, Hanwook Song, Kwangsoo No.
Department of Material Science and Engineering, KAIST, Daejeon 305-701, Republic of Korea and
Nanoscience and Technology Division, Argonne National Laboratory, Lemont, IL 60439, USA and
Center for Mass and Related Quantities, KRISS, Daejeon, Republic of Korea.
An autocatalytic electro-less plating of nickel is attempted to replace an electroless impregnation-reduction (IR) method in ionic polymer–metal composite (IPMC) actuators to reduce cost and processing time. Because nucleation time of Pd–Sn colloids is the determining factor of overall processing time, we used the nucleation time as our control parameter. To optimize nucleation time and investigate its effect on the performance of IPMC actuators, we analyzed the relationship between the nucleation time, interface morphology and electrical properties. The optimized nucleation time was 10 h. The trends of the performance and electrical properties as a function of nucleation time were attributed to the fact that the Ni penetration depth was determined by the minimum diffusion length of either Pd–Sn colloids or reducing agent ions. The Ni-IPMC actuators can be fabricated less than 14 h processing time without deteriorating performance of the actuators, which is comparable to Pt-IPMC prepared by IR method.
Electro-active polymers (EAPs), which show a change in size or shape when stimulated by an electric field are very promising transduction materials.EAPs are used for applications including energy harvesting, biomimetic robots, artificial muscles and micro- and nano-electromechanical systems (MEMS and NEMS) due to their flexibility, low weight, fracture tolerance and ability to be molded into a desirable configuration. There are many EAPs materials such as polymer gel, ferroelectric polymers,dielectric elastomer, ionic polymer-metal composites (IPMC) and conductive polymers.
Among EAPs, IPMC is one of the promising materials as actuators due to relatively large displacement under low voltage (< 5 V), relative insensitivity to damage and actuation capability in both dry and wet conditions. IPMC is composed of an ionic polymer membrane plated with metal electrodes on both surfaces. Up until now the electrodes of choice for IPMC havegenerally been noble metals such as Pt and Au due to their good chemical stability and electrical conductivity. The metal is mostly plated by electroless impregnation-reduction (IR) method in which the metal cation is incorporated inside the membrane and later reduced by the aid of reducing agent. Although IPMC prepared by electroless IR method of noble metal exhibit good actuation performance, the main drawback is the time consuming and expensive processing.
An autocatalytic electro-less plating of nickel is attempted to replace an electroless IR method in IPMC actuators to reduce cost and processing time.Because nucleation time of Pd-Sn colloids is the determining factor of overall processing time, we used the nucleation time as our control parameter. A relationship between nucleation time in the Ni autocatalytic electroless plating and the bending response of IPMC actuators is developed.The optimized nucleation time was 10 hrs. The trends of the performance as a function of nucleation time were attributed to the fact that the Ni penetration depth was determined by the minimum diffusion length of either Pd-Sn colloids or reducing agent ions.The Ni-IPMC actuators with the optimized 10 hrsnucleationtime show a comparable displacement to Pt-IPMC actuators produced by conventionalIR method.