Enhancing the stability of spontaneously self-assembled vesicles - the effect of polymer architecture

Sustainable formulation polymers for home, beauty and personal care: challenges and opportunities

As society moves towards a net-zero future, the need to adopt more sustainable polymers is well understood, and as well as plastics, less visible formulation polymers should also be included within this shift. As researchers, industries and consumers move towards more sustainable products there is a clear need to define what sustainability means in fast moving consumer goods and how it can be considered at the design stage. In this perspective key challenges in achieving sustainable formulation polymers are highlighted, and opportunities to overcome them are presented.

Phase Diagram Study of Catanionic Surfactants Using Dissipative Particle Dynamics

Dissipative particle dynamics (DPD) simulations has been performed to study the phase transition of a mixture of cationic and anionic surfactants in an aqueous solution as a function of the total concentration in water and the relative ratio of surfactants. The impact of the relative difference between the tail lengths of the cationic and anionic surfactants on the phase diagram has been simulated by tuning the number of DPD beads in the simulation model. This research also discusses the impact of the frequently used values of the parameters associated with the harmonic bonds among the bonded DPD beads on the obtained self-assemblies. We find remarkable differences in the resultant self-assemblies based on different choices of harmonic bond parameters. The performed simulations show an enhanced spectrum of self-assemblies with augmented tail lengths and disparate harmonic bond parameters. The obtained self-assemblies are quite unique and can potentially be used in the future for various applications. We also compare the simulation results of the vesicle structures obtained by modeling the electrostatic interaction in the simulation among the charged beads by explicitly introducing charges with a long-range interaction with those obtained by tuning the implicit electrostatic interaction without the long-range interaction. The effects of the chain length of the model and the harmonic bond parameters on the internal density of DPD beads and stress profiles within the vesicles are examined closely. These results are a significant contribution to understanding the stability of the phases and tailoring of the desired vesicles.

Formation of Well-Defined Vesicles by Styrene Addition to a Nonionic Surfactant and Their Polymerization Leading to Viscous Hybrid Systems

Self-assembled structures in aqueous solutions can be fixed by polymerization after adding hydrophobic monomers and can thereby be used as templates which allow to substantially alter the properties of these systems. In this work, we started from a self-assembled micellar system consisting of the nonionic surfactants tetradecyldimethylamine oxid and Pluronic L35 to which styrene was added as a polymerizable monomer. Interestingly, it was observed that styrene induces a transition from micelles to well-defined vesicles in a similar manner as a typical cosurfactant. The structural transition of the aggregates upon styrene addition as well as the structures formed after initiating a polymerization reaction were investigated by means of turbidity, dynamic and static light scattering, small-angle neutron scattering, and rheology measurements. Especially the scattering results confirmed the interesting effect of styrene on the mesoscopic structure and showed a structural evolution from rod-like micelles for low styrene concentrations to vesicles at intermediate styrene amounts, and then finally the formation of microemulsion droplets for high styrene content. Their polymerization of the vesicles again leads to a shape change to wormlike, polymerized aggregates, whose presence then results in rather viscous systems. In contrast, the microemulsions with higher styrene content then are templated and retain their size after polymerization, thereby leading to nanolattices.

PEG coated vesicles from mixtures of Pluronic P123 and l-α-phosphatidylcholine: structure, rheology and curcumin encapsulation

PEG coated vesicles are important vehicles for the passive targeting of anticancer drugs. With a view to prepare PEG decorated vesicles using co-assembly of block copolymers and lipids, here we investigated the microstructure of aggregates formed in mixtures comprising lipids (l-α-phosphatidylcholine) and block copolymers (Pluronic P123), in the polymer rich regime. DLS and SANS studies show that the structure of the aggregates can be tuned from micelles to rod-like micelles or vesicles by changing the lipid to polymer composition. Rheological studies on gels formed by mixtures of polymer and lipid suggest incorporation of the lipid into the polymer matrix. The encapsulation efficiencies of polymer incorporated liposomes for curcumin and doxorubicin hydrochloride (DOX) are evaluated at different drug to carrier ratios. The pH dependent sustained release of both the drugs from the PEGylated liposomes suggests their application in the development of cost effective formulations for anticancer drug delivery.