Large Multipurpose Exceptionally Conductive Polymer Sponges Obtained by Efficient Wet‐Chemical Metallization

Abstract

6182 wileyonlinelibrary.com fi brous segments. Sponges are typically highly porous and easily permeable by gases. Metallization of such sponges could give novel polymer/metal composites with highly interesting properties for a variety of applications, e.g., electrodes in fuel cells, membranes, fi ltration, thermal insulation, heating, ultralight constructions, and catalysis. Well-established metallization techniques for polymer materials include physical or chemical vapor deposition and galvanization. [ 4 ] These techniques are not suitable for achieving high conductivities by the metallization of macroscopic polymer sponges due to their complex 3D structure. The in-depth import of metals inside the pores of sponges and the formation of fully covered metal layers on the polymer fi brous segments are particular problems. A method of choice could be wet metallization, also assigned as electroless plating. There are some reports on wet metallization of porous polymer surfaces following different concepts. For example, gold coating of electrospun poly(methyl methacrylate) nonwovens was achieved by wet deposition of gold nanoparticles (NPs), which yielded conductivities up to 930 S cm −1 .[ 5 ] Here, copper would be more appropriate for many applications. Major pathways for copper plating of polymers are based on the treatment with copper salts and formaldehyde. [ 6 ] Wet chemical deposition of copper, for example, was achieved by treatment of an open-cell polyurethane sponge with CuSO 4 and formaldehyde under basic conditions using PdCl 2 as an activator. [ 7 ] Plasmonic copper nanoparticle coatings were prepared on silanized glass slides following an elegant approach also using CuSO 4 and formaldehyde, but gold as seed. [ 8 ] A number of efforts were undertaken using ultrasound for fast electroless plating. [ 9 ] However, ultrasound-assisted electroless plating required careful adjustment of the ultrasound frequency in order to avoid the pitting of the metal surface due to microjetting, which could also be a major problem in the absence of ultrasound due to evolving hydrogen bubbles. [ 10 ] The importance of the quality of the metal layer obtained by electroless plating on polymer substrates corresponds directly with their electrical properties. Broken and grainy metal layers or pitted surfaces will reduce their electrical conductivity signifi cantly. However, nickel electrodes were produced with polyurethane foams under suitable plating conditions. [ 11 ] The polyurethane foams served as sacrifi cial templates. As a result, highly conductive nickel sponges with high porosities of up to 98% and pore sizes of several

Layer by layer electroless deposition: An efficient route for preparing adhesion-enhanced metallic coatings on plastic surfaces

“…By using the hot chromic acid-sulfuric acid cleaning of plastic surface followed by activation with tin chloride and palladium chloride solutions, the conventional plating processes for metallization of polymer are commonly expensive and toxic [20,21]. Therefore, many latest studies [22][23][24][25] have been reported to develop low-cost and environmentally friendly methods for improvement of adhesion between metal coating and the substrate.…”

Ultralight Biomass‐Derived Carbonaceous Nanofibrous Aerogels with Superelasticity and High Pressure‐Sensitivity

“…Ultralight carbonaceous aerogels are attractive for their fascinating features in terms of low apparent density, good electrical conductivity, large surface area, high porosity, and chemical inertness, which have been widely studied for electrical, biomedical, environmental, and energy applications . In the ultralow range below 5 mg cm −3 , relatively few aerogels currently exist: fullerene aerogels (>1.5 mg cm −3 ), graphene sponges (>0.3 mg cm −3 ), aerographite (>0.22 mg cm −3 ), carbon nanotube aerogels (>0.16 mg cm −3 ), and carbon nanoribbon foams (>4.3 mg cm −3 ) .…”

Superamphiphobic, Magnetic, and Elastic Silicone Sponges with Excellent Temperature Stability

“…The droplets of water, diiodomethane, toluene, and n ‐hexadecane could easily roll off from the surface of the 13° tilted SAME sponge owing to the existence of the air cushion between the sponge and the droplets. [9a] The SAME sponge therefore can float on the surface of toluene. Once immersed in toluene by an external force, the SAME sponge was reflective in toluene (Figure b).…”

“…Guo and co‐workers reviewed the recent progress about the applications of superhydrophobic 3D‐PMs for oil/water separation . Greiner and co‐workers reported preparation of conductive and superhydrophobic 3D‐PMs by efficient wet‐chemical metallization, which could be highly interesting for heating and insulation devices …”