Compliant, Robust, and Truly Nanoscale Free-Standing Multilayer Films Fabricated Using Spin-Assisted Layer-by-Layer Assembly** By Chaoyang Jiang, Sergiy Markutsya, and Vladimir V. Tsukruk* Layer-by-layer (LbL) assembly, [1] which is based on alternating electrostatic adsorption of oppositely charged organic and inorganic materials (polyelectrolytes, [1] dendri- mers, [2] proteins, [3] clays, [4] and nanoparticles [5,6] ) has been ap- plied for the fabrication of a wide variety of functional ultra- thin organized films. [7] These films with tunable internal multilayered organization have potential applications in nano- electronic, optoelectronic, and magnetic technologies, as well as for opto-mechanical, chemical, and bio-sensing, and nano- tribology. [7±9] Recently, the new approach of spin self-assembly [10] or spin- assembly [11] was suggested, which combined the spin coating and LbL techniques to make a cost- and time-efficient tech- nology for the fabrication of multilayered films from polyelec- trolytes, dendrimers, and inorganic nanoparticles on planar substrates. [10±13] It has been shown that, in the framework of this approach, fast and efficient layer deposition under shear forces resulted in well-ordered multilayered structures with modest non-uniformity of the films and some properties dif- ferent from ªconventionalº LbL films. However, this ap- proach was not pushed to the limit and used to fabricate mul- tilayered, nanoparticle-containing, truly nanoscale LbL films with exceptional mechanical parameters in the most demand- ing free-suspended or free-standing state where overall integ- rity and stability of the nanoscale films with macroscopic lat- eral dimensions play a critical role. Free-standing organized organic±inorganic films are considered as prospective sensing compliant membranes for photo-, opto-, and thermal micro- devices. [14] To date, several different approaches were implemented for the fabrication of free-standing nanoscale films from polymers and inorganic nanoparticles: cast films, [15] ªgrowth fromº reac- tions on the patterned surface, [16] crosslinking of amphiphilic Langmuir films, [17] and the deposition of LbL multilayers onto a sacrificial or pH sensitive substrate. [18±20] However, all these approaches included slow (from hours to days), multistep rou- tines, e.g., in the Langmuir approach: monolayer formation, deposition, and crosslinking. Moreover, the multilayer LbL films are either limited to modestly thin (100±300 nm) poly- mer films or thick (300±5000 nm) composite organic±inorgan- ic (with inorganic particles, platelets, fibers) films with vari- able uniformity. Usually, the thinner LbL films were extremely fragile. Thus, corresponding composite films must be made relatively thick to accommodate filler irregularities. The mechanical characteristics achievable for these films are characterized by the elastic modulus values of several gigapas- cal and ultimate tensile strength of 40±70 MPa with a record value for carbon-nanotube-reinforced films of 220 GPa. [19] In this communication, we report the fabrication of compli- ant, highly uniform, extremely robust, smooth, and long-living free-standing nanoscale membranes with excellent mechani- cal characteristics from polyelectrolyte multilayers with a cen- tral interlayer containing gold nanoparticles (Fig. 1a). The COMMUNICATIONS Adv. Mater. 2004, 16, No. 2, January 16 DOI: 10.1002/adma.200306010  2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 157 ± [*] Prof. V. V. Tsukruk,Dr. C. Jiang,S. Markutsya DepartmentofMaterialsScienceandEngineering IowaStateUniversity GilmanHall,Ames,IA50011(USA) E-mail:vladimir@iastate.edu [**] We thank Dr. Yuri Pikus and M. Ornatska for useful assistance.This work was supported by the NSF, CTS-0210005 Grant, AFOSR, F496200210205 Grant, NASA, NAG 102098 Contract, and Depart- ment of Commerce, M01-C03 Grant through The National Textile Center. Figure 1. a) Sketch of the microstructure of the free-standing film with a centralgoldnanoparticleintralayersandwichedbetweentwosymmetrical polymermultilayers(n =3isselectedforillustration);b) large-scaletopo- graphical image of (PAH-PSS) 7 PAH/Au/PAH(PSS-PAH) 7 SA-LbL film on the silicon substrate; c) UV-vis spectrum for (PAH-PSS) 7 PAH/Au/ PAH(PSS-PAH) 7 demonstrating major adsorption bands caused by PSS adsorption as well as individual and collective surface-plasmon reso- nanceswithinthegoldnanoparticleintralayer.