Mechanical Properties of Solidifying Assemblies of Nanoparticle Surfactants at the Oil–Water Interface

Journal Article · Thu Sep 19 00:00:00 EDT 2019 · Langmuir

DOI:https://doi.org/10.1021/acs.langmuir.9b01575· OSTI ID:1634053

Toor, Anju  ^[1]; Forth, Joe ^[2]; Bochner de Araujo, Simone  ^[3]; Merola, Maria Consiglia ^[3]; Jiang, Yufeng ^[4]; Liu, Xubo ^[5]; Chai, Yu  ^[4]; Hou, Honghao ^[2]; Ashby, Paul D.  ^[2]; Fuller, Gerald G. ^[3]; Russell, Thomas P.  ^[6]

---

1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Stanford Univ., CA (United States)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Beijing Univ. of Chemical Technology (China)
6. Beijing Univ. of Chemical Technology (China); Univ. of Massachusetts, Amherst, MA (United States); Tohoku Univ., Aoba (Japan); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

The effect of polymer surfactant structure and concentration on the self-assembly, mechanical properties, and solidification of nanoparticle surfactants (NPSs) at the oil-water interface was studied. The surface tension of the oil-water interface was found to depend strongly on the choice of the polymer surfactant used to assemble the NPSs, with polymer surfactants bearing multiple polar groups being the most effective at reducing interfacial tension and driving the NPS assembly. By contrast, only small variations in the shear modulus of the system were observed, suggesting that it is determined largely by particle density. In the presence of polymer surfactants bearing multiple functional groups, NPS assemblies on pendant drop surfaces were observed to spontaneously solidify above a critical polymer surfactant concentration. Interfacial solidification accelerated rapidly as polymer surfactant concentration was increased. On long timescales after solidification, pendant drop interfaces were observed to spontaneously wrinkle at sufficiently low surface tensions (approximately 5 mN m^-1). Interfacial shear rheology of the NPS assemblies was elastic-dominated, with the shear modulus ranging from 0.1 to 1 N m^-1, comparable to values obtained for nanoparticle monolayers elsewhere. Finally, our work paves the way for the development of designer, multicomponent oil-water interfaces with well-defined mechanical, structural, and functional properties.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1634053
• Journal Information: Langmuir, Vol. 35, Issue 41; ISSN 0743-7463
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
surface tension
interfaces
liquids
surfactants
polymers