Direct Measurements of kT-Scale Capsule–Substrate Interactions and Deposition Versus Surfactants and Polymer Additives

Abstract

We report a novel approach to directly measure the interactions and deposition behavior of functional capsule delivery systems on glass substrates versus the concentration of an anionic surfactant sodium lauryl ether sulfate (SLES) and a cationic acrylamide-acrylamidopropyltrimonium copolymer (AAC). Analyses of three-dimensional optical microscopy trajectories were used to quantify lateral diffusive dynamics, deposition lifetimes, and potentials of mean force for different solution conditions. In the absence of additives, negatively charged capsule surfaces yield electrostatic repulsion with the negatively charged substrate, which inhibits deposition. With an increasing SLES concentration below the critical micelle concentration (CMC), capsule-substrate electrostatic repulsion is mediated by the charged surfactant solution that decreases the Debye length. Above the SLES CMC, depletion attraction causes enhanced deposition until eventually depletion repulsion inhibits deposition at concentrations ∼10 wt %. Addition of an ACC causes deposition via capsule-substrate bridging at all concentrations; the weakest deposition occurs at intermediate AAC concentrations from a competition of steric repulsion and attraction via a few extended bridges. The novel measurements and models of capsule interactions and deposition on substrates in this work provide a basis to fundamentally understand and rationally design complex rinse-off cleansing formulations with optimal characteristics.

Structuring of Si into Multiple Scales by Metal‐Assisted Chemical Etching

“…The MaCE can also be applied to semiconductors other than Si, such as Ge, [146][147][148] GaAs, [149][150][151][152][153][154][155][156][157][158][159][160][161][162][163][164] Al x Ga 1−x As, [165] GaN, [166,167] GaP, [168] InP, [169][170][171][172] SiC, [173,174] and Ga 2 O 3 [175] to fabricate various nanostructures. These compound semiconductors find widespread applications in electronics, optoelectronics, and photovoltaics, etc.…”

Shape Dependent Colloidal Deposition and Detachment

“…The energy landscape of a buckled spherical colloidal particle experiencing van der Waals attraction with the substrate (15)) versus aspect ratio, r z /r x , and attractive potential energy well minimum, U M /k B T. Square data points represent simulated results for log(K) was interpolated contour plot lines. (Figure 5a) is obtained from a model chimeric particle of a hemisphere fused to a hemi-elliptical toroid (Equations (4)- (7)). The net potential takes into account van der Waals attraction and a short-range steric repulsion that yields 1 k B T of attraction at contact on the spherical side (180 o , via Equation (1)) and ß7 k B T of attraction at contact on the buckled side (0 o , via Equation (7)).…”

“…The ability to synthesize a variety of colloidal particle shapes on the micro-and nanoscale has existed for many years [1] and has continued to significantly expand in recent years, [2,3] which has enabled the use of different shaped colloids in diverse technological areas. For example, it is known that colloid shape can enhance drug circulation [4] and cell internalization, [5] fragrance capsule deposition in consumer products, [6,7] hydrodynamic separation processes, [8] environmental transport, [9,10] and specificity in natural systems such as pollen. [11] Beyond this representative list of illustrative examples, a vast literature too expansive to summarize here documents a rich and complex landscape of novel The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adts.201900085 DOI: 10.1002/adts.201900085 behaviors and properties of nonspherical colloids.…”

“…Fragrance capsules are highly engineered to control their stability within formulations, deposition on substrates, and release of fragrant contents. For example, contact adhesion can be increased by chemical surface modification, including species adsorbed from solution as well as specific interactions mediated by peptides . In an example of another design constraint, composite capsule shells can be carefully designed to retain fragrant oils until capsules are ruptured for fragrance release .…”

Controllable Fragrance Release Mediated by Spontaneous Hydrogen Bonding with POSS–Thiourea Derivatives

“…[8][9][10][11][12][13] For instance, the fragrance molecules are enclosed in polymeric materials that can release the fragrances upon the breakage or diffusion of shells. [14][15][16][17][18][19][20][21][22][23][24][25][26] In contrast to physical encapsulation, chemical approaches of profragrances have been developed by Herrmann and others, with chemically covalent binding of volatile molecules to the proper substrates duringthe formation ofprofragrance non-volatiles, 1,[27][28][29][30][31][32][33] wherein the volatile perfume molecules are chemically released with cleavage of a covalent bond or a weak interaction such as hydrogen bond.…”