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. 2021 Oct 8;14(19):5895.
doi: 10.3390/ma14195895.

Synthesis of Polyamide-Based Microcapsules via Interfacial Polymerization: Effect of Key Process Parameters

Angeliki D Mytara  1 , Konstantina Chronaki  1 , Vasilis Nikitakos  1 , Constantine D Papaspyrides  1 , Konstantinos Beltsios  2 , Stamatina Vouyiouka  1
Affiliations

Synthesis of Polyamide-Based Microcapsules via Interfacial Polymerization: Effect of Key Process Parameters

Angeliki D Mytara et al. Materials (Basel). .

Abstract

Polyamide microcapsules have gathered significant research interest during the past years due to their good barrier properties; however, the potential of their application is limited due to the fragility of the polymeric membrane. Fully aliphatic polyamide microcapsules (PA MCs) were herein prepared from ethylene diamine and sebacoyl chloride via interfacial polymerization, and the effect of key encapsulation parameters, i.e., monomers ratio, core solvent, stirring rate and time during the polymerization step, were examined concerning attainable process yield and microcapsule properties (shell molecular weight and thermal properties, MC size and morphology). The process yield was found to be mainly influenced by the nature of the organic solvent, which was correlated to the diffusion potential of the diamine from the aqueous phase to the organic core through the polyamide membrane. Thus, spherical microcapsules with a size between 14 and 90 μm and a yield of 33% were prepared by using toluene as core solvent. Milder stirring during the polymerization step led to an improved microcapsule morphology; yet, the substantial improvement of mechanical properties remains a challenge.

Keywords: encapsulation; interfacial polymerization; microcapsule morphology; polyamide 210; polyamide microcapsules.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
pH and degree of hydrolysis of sebacoyl chloride under emulsification conditions.
Figure 2
Figure 2
FTIR spectra of MC1 and Control samples.
Figure 3
Figure 3
TGA (a) and DSC (b) curves of MC1 and Control samples after filtration and drying.
Figure 4
Figure 4
Morphology of (a) MC1 prior to filtration, (b) Control experiment after filtration (c) MC1 after filtration and (d) MC1 after drying at 40 °C and redispersion.
Figure 5
Figure 5
Mean size and calculated polydispersity index of MCs based on optical microscopy data and using ImageJ software.
Figure 6
Figure 6
SEM images of MC1 after washing with water, filtration and drying at 40 °C (a) magnification 200× (b) magnification 1600×.
Figure 7
Figure 7
Morphology of (a) MC1; (b) MC2 (ratio 5:1); (c) MC3 (hexane) (d) MC4 (toluene); (e) MC5 (100 rpm, 0.5 h); (f) MC6 (100 rpm, 2 h). All images refer to MCs prior to filtration.
Figure 7
Figure 7
Morphology of (a) MC1; (b) MC2 (ratio 5:1); (c) MC3 (hexane) (d) MC4 (toluene); (e) MC5 (100 rpm, 0.5 h); (f) MC6 (100 rpm, 2 h). All images refer to MCs prior to filtration.
Figure 8
Figure 8
Intrinsic viscosity and process yield values of MCs and membranes produced by three different organic solvents.
Figure 9
Figure 9
TGA graphs of (a) MC1, MC3 and MC4 and (b) their respective membranes MD, MH, MT. All samples are MCs and membranes respectively after filtration and drying.
Figure 10
Figure 10
Morphology of (a) MC7 prior to filtration, (b) after filtration and redispersion (c,d) SEM images of MC7 after filtration.
See this image and copyright information in PMC

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