Sparnacci Katia, Antonioli Diego, Gianotti Valentina, Laus Michele, Lupi Federico Ferrarese, Giammaria Tommaso Jacopo, Seguini Gabriele, Perego Michele
†Dipartimento di Scienze e Innovazione Tecnologica (DISIT), Universitá del Piemonte Orientale "A. Avogadro", Viale T. Michel 11, 15121 Alessandria, Italy.
‡INSTM, UdR, Alessandria, Italy.
ACS Appl Mater Interfaces. 2015 May 27;7(20):10944-51. doi: 10.1021/acsami.5b02201. Epub 2015 May 15.
Hydroxyl-terminated P(S-r-MMA) random copolymers (RCPs) with molecular weights (Mn) from 1700 to 69000 and a styrene unit fraction of approximately 61% were grafted onto a silicon oxide surface and subsequently used to study the orientation of nanodomains with respect to the substrate, in cylinder-forming PS-b-PMMA block copolymer (BCP) thin films. When the thickness (H) of the grafted layer is greater than 5-6 nm, a perpendicular orientation is always observed because of the efficient decoupling of the BCP film from the polar SiO2 surface. Conversely, if H is less than 5 nm, the critical thickness of the grafted layer, which allows the neutralization of the substrate and promotion of the perpendicular orientation of the nanodomains in the BCP film, is found to depend on the Mn of the RCP. In particular, when Mn = 1700, a 2.0 nm thick grafted layer is sufficient to promote the perpendicular orientation of the PMMA cylinders in the PS-b-PMMA BCP film. A proximity shielding mechanism of the BCP molecules from the polar substrate surface, driven by chain stretching of the grafted RCP molecules, is proposed.
将分子量（Mn）在1700至69000之间且苯乙烯单元分数约为61%的羟基封端的P（S-r-MMA）无规共聚物（RCPs）接枝到氧化硅表面，随后用于研究圆柱状PS-b-PMMA嵌段共聚物（BCP）薄膜中纳米域相对于基底的取向。当接枝层的厚度（H）大于5 - 6 nm时，由于BCP薄膜与极性SiO2表面有效解耦，总是观察到垂直取向。相反，如果H小于5 nm（接枝层的临界厚度），发现其允许基底中和并促进BCP薄膜中纳米域的垂直取向，这取决于RCP的Mn。特别地，当Mn = 1700时，2.0 nm厚的接枝层足以促进PS-b-PMMA BCP薄膜中PMMA圆柱的垂直取向。提出了一种由接枝的RCP分子链拉伸驱动的BCP分子与极性基底表面的近程屏蔽机制。
