As technology continues towards smaller, thinner and lighter devices, more stringent demands are placed on thin polymer films as diffusion barriers, dielectric coatings, electronic packaging and so on. Therefore, there is a growing need for testing platforms to rapidly determine the mechanical properties of thin polymer films and coatings. We introduce here an elegant, efficient measurement method that yields the elastic moduli of nanoscale polymer films in a rapid and quantitative manner without the need for expensive equipment or material-specific modelling. The technique exploits a buckling instability that occurs in bilayers consisting of a stiff, thin film coated onto a relatively soft, thick substrate. Using the spacing of these highly periodic wrinkles, we calculate the film's elastic modulus by applying well-established buckling mechanics. We successfully apply this new measurement platform to several systems displaying a wide range of thicknessess (nanometre to micrometre) and moduli (MPa to GPa).

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The intermolecular self‐crosslinking of functionalized macromolecules under ultra‐dilute conditions (see Figure) provides a versatile approach to the preparation of nanoparticles with very small sizes. The size and the chemical nature of the particles are easily controlled and the use of particles produced in this way in the generation of nanoporous thin films where the particles act as sacrificial porogens has been demonstrated.

Nanoporous materials are often accessed by a supramolecular approach using soft matter templates. Porous silicates and organosilicates synthesized by wet chemistry processes have been intensively studied for the last 20 years. Due to the versatility of the sol-gel chemistry, thermally sensitive bonds, organic molecules [1] and polymers [2] can be introduced either at the pore surfaces or in the network, and pore size, distribution and organization can be controlled as well.[3] The combination of the most important properties of the inorganic and organic components, coupled with the control of the "empty space" has suggested many potential applications for these materials.[4] For example, several thin-film applications in emerging optical, electronic, biological and filtration technologies have been envisioned. [5,6] Until now, a major roadblock in the realization of technological applications for these materials seems to be their poor mechanical properties. Indeed, the incorporation of pores into brittle glasses often has a catastrophic effect on their mechanical and fracture properties. This behavior is even more pronounced when moving from silicate to organosilicate materials (ORMOSILS) due to a decrease in network atom connectivity, impacting potential applications for these materials. A case in point is the observation that the fracture energy value, G c , for dense methylsilsesquioxane (MSSQ) glass is typically less than 5 J.m -2 , as compared to 10 J.m -2 for SiO 2 . [7] The presence of methyl substituents, while useful to lower the dielectric constant, generate free volume and impart hydrophobicity, simultaneously reduces the density, modulus, hardness and fracture energy. [7][8][9][10] We have recently demonstrated that these organosilicates show a strong power relationship dependence between film density and mechanical properties (e.g. modulus and fracture resistance), resulting in a rapid decay of the latter with increase in porosity. [7] For MSSQ materials, unfortunate consequences of this are: a) at low level of porosity the modulus decreases extremely rapidly (e.g. 50 % reduction at 15 vol.% porosity), b) at higher porosities (> 30 %), the modulus vs density curves tend to converge, abrogating any anticipated benefits by starting from dense materials with higher modulii.[11] Without acceptable fracture resistance, porous organosilicate glasses would be of little utility in any of the applications cited above. This statement is especially applicable to microelectronics, where dense organosilicate materials containing varying amount of Si-Me substitutents (k = 2.7-3.0) are currently used as the insulating layers in 90 nm interconnect technology, [12,13] and porous analogs will be implemented in future electronic devices. [14,15] Escalating integration issues are anticipated for materials with increased porosity since many of the integration processes require good mechanical properties (e.g. chemical mechanical polishing, chip dicing, wire bonding, etc). [16,17] Mechanical instability and the associated...

Nanoporous methyl silsesquioxane (MSSQ), which is an important and promising candidate for spin-on ultralow dielectric constant applications, has been produced via the thermosetting of MSSQ, templated by a nanodispersed, thermally decomposable pore generator (porogen)poly(methyl methacrylate-co-dimethylaminoethyl methacrylate) [P(MMA-co-DMAEMA)]. Fourier transform infrared spectroscopy is used to study the interaction and structural changes of MSSQ/P(MMA-co-DMAEMA) nanocomposites as a function of curing temperature (ranging from 25 to 450 °C) and porogen loading (ranging from 0 to 70 wt %). We find that strong hydrogen-bonding interactions occur between the -OH end groups in MSSQ and the tertiary amino groups in P(MMA-co-DMAEMA) in films at 25 °C. An increase in cure temperature from 25 to 250 °C and finally to 450 °C transforms MSSQ from a material with many reactive end groups to a highly cross-linked structure. In addition, the amino substituent in P(MMA-co-DMAEMA) can act as a catalyst for the condensation and crosslinking of MSSQ. An increase of porogen loading to 70 wt % and a decrease in the silanol group concentration in MSSQ both hinder the formation of the -Si-O-Si-network. Finally, small-angle X-ray scattering (SAXS) results indicate that MSSQ resins initially having higher -OH end group concentrations ultimately generate smaller pores after the removal of porogens.

Multilayer nanoporous films generated by a layer‐by‐layer spin‐on method are presented (see Figure). Precise control of the porosity of the individual layers that comprise the multilayer structure is demonstrated. Due to the simplicity of this fabrication method a wide range of potential applications in the areas of separation science, biotechnology, optics etc. are envisaged.