Well-Organized Dense Arrays of Nanodomains in Thin Films of Poly(dimethylsiloxane)-b-poly(lactide) Diblock Copolymers

Thin films with well-organized arrays of densely packed nanodomains were fabricated from poly(dimethylsiloxane)-b-poly(DL-lactide) (DL) diblock copolymers. As a consequence of the unusually large Flory-Huggins interaction parameter between these repeat units, domains with sizes similar to 10 nm are routinely generated using low molar mass diblock copolymers. Different morphologies are easily accessible by judiciously adjusting the block composition, garnering dot patterns (from spheres) and line patterns (from parallel cylinders) in a facile manner. The strong incompatibility also allows retention of order at relatively low molar mass even with high degrees of compositional asymmetry (e.g., f(L) similar to 0.15). Block copolymers with various compositions are shown to form well-organized morphologies on various substrates and thermal annealing readily enhanced long-range order. All block copolymers were prepared on a >10 g scale, and the processing conditions are compatible with the current infrastructure of the microelectronics industry, demonstrating a strong potential for commercial relevance.