Reversible stability of colloids switched by CO<sub>2</sub> based on polyhexamethylene guanidine.
basic_science · Level V
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- Record sourced from PubMed, PMID 36227104.
- Also identified by DOI 10.1039/d2sm00811d.
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Abstract
The stability of a colloid, including emulsion and polymer latex, can be destroyed irreversibly by the addition of salt. Using the CO<sub>2</sub> stimulus, amines can be converted into organic ammonium salts reversibly, which can access the switching of colloids. Polyhexamethylene guanidine (PHMG), was chosen as a switchable amine. The conductivity of PHMG aqueous solution switched by adding and removing CO<sub>2</sub>. Surface tension measurements verified that, under CO<sub>2</sub>, the critical micelle concentration of sodium dodecyl benzene sulfonate (SDBS) decreased from 1.0 × 10<sup>-3</sup> to 5.0 × 10<sup>-4</sup> M with the addition of PHMG. The crude oil emulsion containing SDBS and PHMG was destroyed and restored reversibly by the treatment with CO<sub>2</sub> and N<sub>2</sub>. The polystyrene latex also occurred an obvious stratification after sparging with CO<sub>2</sub> and returned a homogeneous phase upon bubbling N<sub>2</sub>. This study is intended to pave the way for colloids which has reversible stability in response to CO<sub>2</sub> stimulation.