A Multi-Scale Approach to Microencapsulation by Interfacial Polymerization

Abstract

This work applies a multi-scale approach to the microencapsulation by interfacial polymerization. Such microencapsulation is used to produce fertilizers, pesticides and drugs. In this study, variations at three different scales (molecular, microscopic and macroscopic) of product design (i.e., product variables, process variables and properties) are considered simultaneously. We quantify the effect of the formulation, composition and pH change on the microcapsules’ properties. Additionally, the method of measuring the strength of the microcapsules by crushing a sample of microcapsules’ suspension was tested. Results show that the xylene release rate in the microcapsules decreases when the amine functionality is greater due to a stronger crosslinking. Such degree of crosslinking increases the compression force over the microcapsules and improves their appearance. When high levels of amine concentration are used, the initial pH values in the reaction are also high which leads to agglomeration. This study provides a possible explanation to the aggregation based on the kinetic and thermodynamic controls in reactions and shows that the pH measurements account for the polyurea reaction and carbamate formation, which is a reason why this is not a suitable method to study kinetics of polymerization. Finally, the method used to measure the compressive strength of the microcapsules detected differences in formulations and composition with low sensibility.

Coacervate Microcapsules of Citrus aurantifolia Essential Oil (LOs): Optimization and Their Antibacterial Activity Study

“…Despite consistent stirring speed and time being applied to all A/G ratios during the encapsulation, the actual effects achieved by each process are plausibly different. In particular, it was due to the different viscosity of the mixture, caused by the disproportional ratio of the shells [42,43] …”

“…In particular, it was due to the different viscosity of the mixture, caused by the disproportional ratio of the shells. [42,43] To investigate the linearity of good morphology of the optimized LOs microcapsules with their performance to release LOs from the shells, time-dependent of LOs release experiments from the microcapsules were conducted against mechanical and chemical interferences (Figure 6). The shells created from A/G of 1 : 3.75 persistently showed remarkable properties, releasing 65 % of LOs in 120 minutes.…”

Biocides and techniques for their encapsulation: a review

“…More information can be found in comprehensive reviews focusing on this technique. [53][54][55] Fig. 3(b) shows a specific example of a natural and hydrophobic biocide (clove oil) being encapsulated in polyurethane (PU) microcapsules using this technique.…”

Self-Stabilizing Encapsulation through Fast Interfacial Polymerization of Ethyl α-Cyanoacrylate: From Emulsions to Microcapsule Dispersions

“…Third, to the extreme of steric hindrance when forming an integral solid shell at the interface, such a specific structure of the dispersed phase can also be considered as the microcapsule. It is worth noting that most of the microcapsules produced by interfacial polymerization are based on emulsion templates, wherein the polymerization processes are time-consuming and interface-active agents are essentially needed. − Specifically, cyanoacrylate-based capsules can be produced via radical polymerization and anion polymerization in a heterogeneous system, with the use of various interface-active agents ( e.g. , Tween 80, Span 20, and dodecyltrimethylammonium chloride). ,, However, the interface-active agents are usually superfluous or even destructive as they change the surface wettability of the microcapsules and present risks to the environment and health. , With rare time cost and no additive interface-active agents, the microcapsule can be readily prepared during the self-stabilizing encapsulation process via the FIP method.…”