title: Thermal stability of functional P(S-r-MMA) random copolymers for nanolithographic applications.
abstract: Two strategies are envisioned to improve the thermal stability of the grafted layer and to allow the processing of the random copolymer/block copolymer (RCP/BCP) system at high temperature. From one side, a high-temperature thermal treatment of a commercial α-hydroxyl ω-2,2,6,6-tetramethylpiperidinyloxy functional RCP, namely, TR58, leads to the formation of a stabilized layer able to induce the perpendicular orientation of a symmetric BCP to temperatures higher than 310 °C. On the other side, an α-hydroxyl ω-Br functional RCP, namely, BrR58, with the same molar mass and composition of TR58, was prepared by activator regenerated by electron transfer atom transfer radical polymerization. The resulting brush layer can sustain the self-assembly of the symmetric BCP for processing temperatures as high as 330 °C. In both systems, the disruption of the BCP film, deposited on the grafted RCP layer, occurs because of the formation of bubbles, due to a low-temperature evolution of monomers from the RCP layer. The extent of the low-temperature monomer evolution is higher for TR58 than it is for BrR58 and starts at lower temperatures. For both copolymers, the thermal treatment offsets the low-temperature monomer evolution while still maintaining surface characteristics suitable to induce the perpendicular orientation of the BCPs, thus ultimately extending the range of processing temperatures of the BCP film and consequently speeding the self-organization process.
authors: Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Università del Piemonte Orientale ''A. Avogadro'' , Viale T. Michel 11, 15121 Alessandria, Italy.
authors: Katia
authors: K
authors: Sparnacci
authors: Diego
authors: D
authors: Antonioli
authors: Valentina
authors: V
authors: Gianotti
authors: Michele
authors: M
authors: Laus
authors: Giampaolo
authors: G
authors: Zuccheri
authors: Federico
authors: F
authors: Ferrarese Lupi
authors: Tommaso Jacopo
authors: TJ
authors: Giammaria
authors: Gabriele
authors: G
authors: Seguini
authors: Monica
authors: M
authors: Ceresoli
authors: Michele
authors: M
authors: Perego
keywords: P(S-r-MMA); PS-b-PMMA; rapid thermal processing; self-assembly; thermal stability