Phase Behavior of Nonionic Microemulsions with Multi-end-capped Polymers and Its Relation to the Mesoscopic Structure

Abstract

The polymer architecture of telechelic or associative polymers has a large impact on the bridging of self-assembled structures. This work presents the phase behavior, small angle neutron scattering (SANS), dynamic light scattering (DLS), and fluorescence correlation spectroscopy (FCS) of a nonionic oil-in-water (O/W) microemulsion with hydrophobically end-capped multiarm polymers with functionalities f = 2, 3, and 4. For high polymer concentrations and large average interdroplet distance relative to the end-to-end distance of the polymer, d/R ee, the system phase separates into a dense, highly connected droplet network phase, in equilibrium with a dilute phase. The extent of the two-phase region is larger for polymers with similar length but higher f. The interaction potential between the droplets in the presence of polymer has both a repulsive and an attractive contribution as a result of the counterbalancing effects of the exclusion by polymer chains and bridging between droplets. This study experimentally demonstrates that higher polymer functionalities induce a stronger attractive force between droplets, which is responsible for a more extended phase separation region, and correlate with lower collective droplet diffusivities and higher amplitude of the second relaxation time in DLS. The viscosity and the droplet self-diffusion obtained from FCS, however, are dominated by the end-capped chain concentration.

The plant dehydrin Lti30 stabilizes lipid lamellar structures in varying hydration conditions

“…It is noted that the calculated value of d w contains both the region of the polar headgroups and interbilayer aqueous layer, and it is therefore reasonable that this value is slightly larger than the length of the unstructured segments of the protein. The bridging behavior of analogues has previously been described for polymer-surfactant systems with flexible hydrophilic chains flanked with segments that associate with the bilayer either through electrostatic or hydrophobic interactions (47)(48)(49)(50).…”

Structure, interfacial film properties, and thermal fluctuations of microemulsions as seen by scattering experiments

“…By offering a hydrophobic 'harbour' to the sticky ends [118], droplet microemulsions of oil in water allowed the detailed control of the number and properties of the transient crosslinks of these networks, and thus of rheology [119,85,120]. By playing with the chemical nature of the triblocks, including fluorination, additional triggers of structure and rheology have been studied [121,122,123,124]. Reviews on modification of interaction between microemulsion droplets exist, see e.g.…”

Gels Obtained by Colloidal Self-Assembly of Amphiphilic Molecules

“…Depending on the relative importance of these contributions, the net interaction is attractive or repulsive [141].…”

“…The effect of the polymer architecture on the structure and dynamics of ME networks has also been studied [141,143]. Low functionality telechelic star polymers with 3 and 4 arms are able to interconnect microemulsion droplets.…”