# Nano-/Microcapsules, Liposomes, and Micelles in
## 2 Spherical Nanoparticles
### Micelles
#### 2.2.2 Methods of Obtaining  
Micelles are created through the self-organisation of amphiphilic polymers in aqueous solutions. Conversely, amphiphilic polymers exist as unimers at low concentrations. When the concentration of amphiphilic polymers is close to the critical micelle concentration (CMC), unimers aggregate to form micelles [71; 72; 86]. The formation of micelles and reverse micelles depends on environmental and structural factors, with their creation predominantly influenced by intermolecular bonds including hydrogen bonds, hydrophobic interactions (amphiphilic micelles), and electrostatic interactions (polyionic micelles). The reduction in interfacial free energy is the primary driver of micellization and its stabilisation. Hydrophobic interaction prevails as the primary mechanism for reducing the interfacial free energy of a block copolymer in aqueous environments. In cases of micellization, the separated core-forming molecules necessitate additional proximity forces to further stabilise the micelles [70]. There are two primary approaches for creating micelles: physical and chemical. The latter involves the formation of a reversible bond between the amphiphilic polymer and the hydrophobic functional component, which enables the encapsulation of the hydrophobic substance into the micelle's core. Unfortunately, this technique is unfit for implementation in the food industry due to the creation of new chemical bonds. In contrast, the physical method involves the self-organisation of the amphiphilic polymer in a solution, with the hydrophobic functional component being encapsulated within the core via hydrophobic interactions and/or hydrogen bonds. Physical methods for the preparation of polymer nanoparticles include direct dissolution, solvent evaporation, dialysis, film hydration, ultrasound-assisted, nanoprecipitation, polymerisation-induced self-assembly (PISA), and oil-in-water emulsion methods [70; 71; 73]. The direct dissolution method is typically utilised for polymers with high water solubility. Micelles are formed when the concentration of polymer exceeds CMC. The polymer self-assembles with gentle agitation in water [87]. In the solvent evaporation method, volatile organic solvents are utilised to enhance the solubility of hydrophobic polymer chains and hydrophobic functional components [73]. The dialysis technique is employed to prepare micelles for poorly soluble polymers and/or functional components. It entails transferring the material and polymer from a solvent in which they can be jointly dissolved to a solvent selective for the hydrophilic chains of the polymer. Under the influence of the selective solvent, hydrophobic polymer chains combine gradually, leading to the emergence of micelle cores. Concurrently, the hydrophobic functional component transfers to the micelle core. Dimethylsulfoxide, ethanol, acetone, and tetrahydrofuran are among the usual solvents employed in this method [88]. The cellular structure of micelles acquired using the dialysis method is more stable and compact in comparison to the solvent method. However, this technique results in significant losses and requires an extended duration [73]. Conversely, the film hydration method utilises volatile organic solvents to dissolve hydrophobic functional components and copolymers. Evaporation eliminates these components in a subsequent step to produce a lean polymer film. Subsequently, polymer micelles are formed upon dissolving the polymer film in water, into which hydrophobic components are loaded [89]. The technique for obtaining micelles assisted by ultrasound is generally reserved for polymers with favourable water solubility, as ultrasound alone is insufficient for encapsulating hydrophobic components and hydrophilic polymers [87]. The encapsulation of water-insoluble components through the oil-in-water emulsion method is a convenient technique for preparing micelles.