Stability and Mechanical Properties of Polyelectrolyte Capsules Obtained by Stepwise Assembly of Poly(styrenesulfonate sodium salt) and Poly(diallyldimethyl ammonium) Chloride onto Melamine Resin Particles

Abstract

Capsules composed of poly(styrene sulfonate, sodium salt) (PSS)/poly(diallyldimethyl ammonium) chloride (PDADMAC) were prepared by layer-by-layer deposition of the polyelectrolytes on melamine formaldehyde colloidal templates followed by the decomposition of the cores by hydrochloride. A yield of more than 90% of intact capsules was achieved if (i) the core diameter was equal to or less than 3.8 µm and (ii) not more than five pairs of layers were adsorbed. When the cores were larger or the layers were thicker, the osmotic pressure difference caused by core dissolution led to an increased frequency of wall rupture. The elasticity modulus of a multilayer consisting of five pairs of PSS/PDADMAC was about 140 MPa as measured by osmotic pressure induced capsule deformation.

Mechanics of artificial microcapsules

“…Thus, an excess of polyelectrolyte inside or outside the capsule creates a uniform force, and the response yields information on mechanical properties. The effect of polyelectrolyte, in the solution, on the capsule shape was investigated by Gao and co-workers [30,31]. Figure 1 presents a series of confocal fluorescence microscopy images of capsules, staining the wall by a dye, on increasing the outside polyelectrolyte (PE) concentration.…”

“…The extent of volume conservation is as well expected to depend on the details of preparation since defects in the capsule walls can dominate the permeability. Consequently, attempts to derive elastic constants of the wall material from the large deformation behaviour assuming zero-membrane permeability have resulted in estimates of the Young modulus in the 1-10 MPa range [49], about a factor of a thousand to a hundred lower than found with other methods [30,31,33].…”

“…concentrations, the osmolarity is no longer linear in the polyelectrolyte concentration and thus independent measurements of the osmotic pressure are necessary which have been carried out for the buckling studies [30,31] and in the swelling studies [33]. In the swelling experiments, (quasi-) static situations are investigated, which have to be taken into account when comparing values with other techniques: on the long time scale the material could molecularly rearrange in a viscoelastic fashion and thus lower elastic constants are to be expected.…”

Kinetics of particle wrapping by a vesicle

“…The wrapping of a particle by a fluid membrane is a phenomenon of widespread and generic interest in biology [1][2][3][4] as well as in a variety of technological applications such as drug delivery, [5][6][7][8][9][10][11][12] gene delivery, 13,14 and the design of nanoreactors [15][16][17][18][19][20][21][22][23][24] which would allow for highly controllable reaction conditions.…”

Depressions at the surface of an elastic spherical shell submitted to external pressure

“…This is not far from the upper and lower limits for N=1, which suggests that it could be worthwhile exploring intermediate values of the osmotic pressure in order to check the presence of configurations presenting a higher number of depressions. In a similar but thinner system (d/R = 0.018), a transition from N=1 towards a higher number of depressions was observed when increasing the osmotic pressure 25 , but a further increase leads to a zoology of tortured shapes for which we do not have a model. With localized occurrence of important curvature, coalescence of distinct depressions can be prevented by high energy barriers.…”