Session B46: Invited Session: Industrial Applications of Advanced Polymer-Based Nanomaterials

Polymer and Material Design for Lithography From 50 nm Node to the sub-16 nm Node

Microlithography is one of the technologies which enabled the Information Age. Developing at the intersection of optical physics, polymer science and photochemistry, the need for ever smaller high fidelity patterns to build integrated circuits is currently pushing the technology evolution from 193 nm immersion lithography to extreme ultraviolet lithography (13.5 nm) to alternate patterning technologies such as directed self assembly (DSA) of block copolymers. Essential to the success of this progression is a rapid application of new concepts and materials in polymer science. We will discuss the requirements for 193 immersion lithography and how advanced acrylic random polymers are being designed with chemical amplification functionality to meet these needs. The special requirements of a water immersion lithography led to the invention and rapid commercial application of surface assembled embedded barrier layer polymers. Design of polymers for EUV lithography is having to respond to much different challenges, prominent being the dearth of photons in the exposure step, and the other being how to maximize the efficiency of photoacid production. In parallel, alternative lithographic approaches are being developed using directed self assembly of block copolymers which realize pattern frequency multiplication. We will update with our progress in the applications of polymers designed for DSA.   

Development of nanostructured surfaces for ice protection applications

Ice accretion on surfaces of aircrafts, wind turbine blades, oil and gas rigs and heat exchangers, to name a few examples, presents long recognized problems with respect to efficiency and cost of operation. For instance, significant ice accretion on critical surfaces of an aircraft will cause problems during lift off (and will change the aerodynamics of the wings during flight. On the other hand, ice built up on wind turbine blades in cold climates (T $<$ -20\r{ }C) drastically reduces the efficiency of power generation. Despite considerable number of studies and significant progress toward development of icephobic coatings, development of \textit{robust ice-resistance or anti-icing coatings} is still elusive. Several approaches towards development of anti-icing surfaces have recently postulated that the superhydrophobic properties of hierarchically textured coatings, with contact angles $>$ 150\r{ }, may lead to a significant reduction and perhaps elimination of snow and ice accretion. However, the exact mechanism of delayed icing on these surfaces is still under debate. Here we present a systematic study of early stages of ice formation upon water droplet impact on a range of hydrophobic, hydrophilic, textured and chemically patterned surfaces. We show that, in addition to a significant reduction in ice-adhesion strength on superhydrophobic surfaces, decreasing the water-substrate contact area plays a \textit{dual} role in delaying ice nucleation: first by reducing heat-transfer and second by reducing the probability of heterogeneous nucleation at the water-substrate interface. The study presented here also offers a comprehensive perspective on the efficacy of textured surfaces for practical non-icing applications.   

Tough Block Copolymer Organogels and Elastomers as Short Fiber Composites

The origins of the exceptional toughness and elastomeric properties of gels and elastomers from block copolymers with semicrystalline syndiotactic polypropylene blocks will be discussed. Using synchrotron X-radiation small angle (SAXS) and wide angle X-ray scattering (WAXS) experiments were simultaneously performed during step cycle tensile deformation of these elastomers and gels. From these results the toughness can be attributed to the formation, orientation and elongation of the crystalline fibrils along the tensile direction. The true stress and true strain $\varepsilon _{H}$ during each cycle were recorded, including the true strain at zero load $\varepsilon _{H,p}$ after each cycle that resulted from the plastic deformation of the sPP crystals in the gel or elastomer. The initial Young's modulus E$_{init}$ and maximum tangent modulus E$_{max}$ in each cycle undergo dramatic changes as a function of $\varepsilon _{H,p}$, with E$_{init}$ decreasing for $\varepsilon _{H,p} \quad \le $ 0.1 and then increasing slowly as $\varepsilon _{H,p}$ increases to 1 while E$_{max }$increases rapidly over the entire range of $\varepsilon _{H,p}$ resulting in a ratio of E$_{max}$/E$_{init} \quad >$ 100 to 1000 at the highest maximum (nominal) strain. Based on SAXS patterns from the deformed and relaxed gels, as well as on previous results on deformation of semicrystalline random copolymers by Strobl and coworkers, we propose that the initial decrease in E$_{init}$ and increase in E$_{max}$ with $\varepsilon _{H,p}$ are due to a breakup of the network of the original sPP crystal lamellae and the conversion of the sPP lamellae into fibrils whose aspect ratio increases with further plastic deformation, respectively. The gel elastic properties can be understood quantitatively as those of a short fiber composite with a highly deformable matrix. At zero stress the random copolymer midblock chains that connect the fibrils cause these to make all angles to the tensile axis (low E$_{init})$, while at the maximum strain the stiff, crystalline sPP fibrils align with the tensile axis producing a strong, relatively stiff gel$. $The evolution of the crystalline structure during deformation is confirmed by WAXS and FTIR measurements.   

Interfacial, Thin Film, and Structural Measurements to Facilitate Polymer Nanomanufacturing

There is a growing interest in coupling the relatively mature roll-to-roll manufacturing processes with advanced lithographic pattering methods to enable high volume manufacturing of technologies with the added functionality that can only be realized by nanoscale pattering. Nanoimprint lithography is particularly attractive for roll-to-roll processes because the patterning is achieved though a simple embossing technique that relies upon the mechanical deformation of a liquid, melt, or solid material via a squeeze-flow process. Embossing techniques on a roll-to-roll substrate are routinely encountered in the graphic arts community. The difference with nanoimprint lithography is that the printed features can be on the order of 10 nm or smaller. In this presentation we will look at some of the difficulties encountered when these roll-to-roll embossing processes are scaled to the nanoscale. In particular we will look at issues related to the viscous flow of high molecular mass polymer melts into the nanoscale cavities with high throughput. We will show how fast nanoscale squeeze-flow pattering can lead to significant plastic deformation of the polymer melt. This can have implications on the ability of the material to fill the mold and the residual stresses that are generated in the pattern through the imprint process. Techniques to quantitatively evaluate these processes will be discussed and related to fundamental concepts of polymer physics.   

Self-Healing Polymer Networks

Supramolecular chemistry teaches us to control non-covalent interactions between organic molecules, particularly through the use of optimized building blocks able to establish several hydrogen bonds in parallel. This discipline has emerged as a powerful tool in the design of new materials through the concept of supramolecular polymers. One of the fascinating aspects of such materials is the possibility of controlling the structure, adding functionalities, adjusting the macroscopic properties of and taking profit of the non-trivial dynamics associated to the reversibility of H-bond links. Applications of these compounds may include adhesives, coatings, rheology additives, high performance materials, etc. However, the synthesis of such polymers at the industrial scale still remains a challenge. Our first ambition is to design supramolecular polymers with original properties, the second ambition is to devise simple and environmentally friendly methods for their industrial production. In our endeavours to create novel supramolecular networks with rubbery elasticity, self-healing ability and as little as possible creep, the strategy to prolongate the relaxation time and in the same time, keep the system flexible was to synthesize rather than a single molecule, an assembly of randomly branched H-bonding oligomers. We propose a strategy to obtain through a facile one-pot synthesis a large variety of supramolecular materials that can behave as differently as associating low-viscosity liquids, semi-crystalline or amorphous thermoplastics, viscoelastic melts or self-healing rubbers.