Interfacial Segregation in Polymer Blends Driven by Acid–Base Interactions

• Published in: Langmuir Vol. 29; no. 51; pp. 15727 - 15731
• Main Authors: Prasad, Shishir, Zhu, He, Kurian, Anish, Badge, Ila, Dhinojwala, Ali
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 23-12-2013
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Surface physical chemistry; Polymer; Acids; Segregation; Base; Interface
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la403418h

Infrared-visible sum frequency generation spectroscopy (SFG) was used to measure the interfacial concentrations of poly(methyl methacrylate) (PMMA)/polystyrene (PS) blends next to a sapphire substrate. The acid–base interactions of carbonyl groups of PMMA with the hydroxyl groups on the sapphire drive the interfacial segregation of PMMA next to the sapphire substrate. Using the shift of sapphire surface OH peaks, we have determined the difference in interfacial energy between the PMMA/sapphire and the PS/sapphire to be ∼44–45 mJ/m2. These results highlight the importance of acid–base interactions and their role in controlling the interfacial segregation next to solid substrates in polymer blends.