posted on 2019-07-29, 17:24authored byTianyi Yu, Lauren T. Swientoniewski, Marzhana Omarova, Mei-Chun Li, Ioan I. Negulescu, Naisheng Jiang, Omead A. Darvish, Abhishek Panchal, Diane A. Blake, Qinglin Wu, Yuri M. Lvov, Vijay T. John, Donghui Zhang
Halloysite
nanotubes (HNTs), naturally occurring and environmental benign clay
nanoparticles, have been successfully functionalized with amphiphilic
polypeptoid polymers by surface-initiated polymerization methods and
investigated as emulsion stabilizers toward oil spill remediation.
The hydrophilicity and lipophilicity balance (HLB) of the grafted
polypeptoids was shown to affect the wettability of functionalized
HNTs and their performance as stabilizers for oil-in-water emulsions.
The functionalized HNTs having relatively high hydrophobic content
(HLB = 12.0–15.0) afforded the most stable oil-in-water emulsions
containing the smallest oil droplet sizes. This has been attributed
to the augmented interfacial activities of polypeptoid-functionalized
HNTs, resulting in more effective reduction of interfacial tension,
enhancement of thermodynamic propensity of the HNT particles to partition
at the oil–water interface, and increased emulsion viscosity
relative to the pristine HNTs. Cell culture studies have revealed
that polypeptoid-functionalized HNTs are noncytotoxic toward Alcanivorax borkumensis, a dominant alkane degrading bacterium
found in the ocean after oil spill. Notably, the functionalized HNTs
with higher hydrophobic polypeptoid content (HLB = 12.0–14.3)
were shown to induce more cell proliferation than either pristine
HNTs or those functionalized with less hydrophobic polypeptoids. It
was postulated that the functionalized HNTs with higher hydrophobic
polypeptoid content may promote the bacterial proliferation by providing
larger oil–water interfacial area and better anchoring of bacteria
at the interface.