Facile fabrication of Sudan red particle microcapsules by a polymerizable gemini surfactant and molecular assembly mechanisms.
basic_science · Level V
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- Record sourced from PubMed, PMID 28180226.
- Also identified by DOI 10.1039/c6sm02799g.
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Abstract
An efficient method was developed to encapsulate water insoluble organic particles of Sudan red III (SR) in aqueous suspensions by using a polymerizable cationic gemini surfactant, 1,3-bis(N,N-dimethyl-N-cetylammonium)-2-(propylacrylate dibromide) (AGC<sub>16</sub>). The AGC<sub>16</sub> coated SR microcapsules (AGC<sub>16</sub>@SR) were prepared by absorption of AGC<sub>16</sub> on the surface of SR, followed by in situ homopolymerization (PAGC<sub>16</sub>). Several measurements, including transmission and scanning electron microscopy, isothermal titration calorimetry, zeta potential, electron paramagnetic resonance and small angle X-ray scattering, were performed to determine the adsorption amount of AGC<sub>16</sub>, and the layer structures and the molecular assembly mechanism in the AGC<sub>16</sub>@SR and PAGC<sub>16</sub>@SR systems, respectively. For comparison purposes, the polymerizable cationic surfactant with one head group and a single alkyl chain, acryloyloxyethyl-N,N-dimethyl-N-cetylammonium bromide (referred to as ASC<sub>16</sub>), as well as the systems of ASC<sub>16</sub>@SR and PASC<sub>16</sub>@SR were also investigated in parallel. It was found that AGC<sub>16</sub> molecules and their aggregates were simultaneously assembled into a shell layer, in which the saturated adsorption amount of AGC<sub>16</sub> on SR is less than 1/2 that of ASC<sub>16</sub>, but the assembly layer of AGC<sub>16</sub> is more hydrophobic with greater packing tightness compared with that of ASC<sub>16</sub>. It was also revealed that after in situ homopolymerization, the microcapsule shell becomes more compact. In the case of PAGC<sub>16</sub>@SR, the layers show higher surface roughness and irregularity compared with that of PASC<sub>16</sub>@SR. Moreover, the sustained release behavior of SR was also evaluated. The results revealed that PAGC<sub>16</sub>@SR performed well for SR controlled release, which was sorted by release performance as the following sequence: PAGC<sub>16</sub>@SR > AGC<sub>16</sub>@SR > PASC<sub>16</sub>@SR > ASC<sub>16</sub>@SR. Thus, the polymerizable cationic gemini surfactant holds substantial potential to be developed as an ideal candidate of soft matter to construct efficient controllable release systems.