Corona chain

From the measured core radii the grafting distance b can be calculated. Its variation as a function of added salt concentration is shown in Fig. 6 a. In the osmotic brush regime at low added salt concentrations the grafting distances are practically constant. At concentrations above c s 0.05 mol/1 ( salted brush ) the grafting distances decrease with increasing salt due to screening of the repulsive interactions between the corona chains [49]. 

Luo L, Eisenberg A (2002) One-step preparation of block copolymer vesicles with preferentially segregated acidic and basic corona chains. Angew Chem Int Ed Engl 41 1001-1004... 

Poly(methylmethacrylate), PMMA, latex particles have also served as a model colloidal system for many years (mainly as hard spheres with hydroxy stearic acid (HSA) chains being the grafting choice [91,113,114]). Tunability was achieved by varying the core size and the size of the corona chains. The comparison between chemically grafted (stable) and end-adsorbed temperature-sensitive chains (usually surfactants) has shown that the adsorbed chain particles exhibit similar rheological behavior with chemically grafted particles [115]. 

There exists a threshold below which the two corona chains mix, and above which the Janus configuration becomes stable. For the symmetric system it was found [67] that this threshold interaction obeys the relationship 2, where... 

Fig. 12 Volume fraction contour plots for a cross-section through a Janus miceUe composed of two types of corona chains iVa = A d = 100, with = kd = 15, and Xbd = 1- The core-forming block has a length Nc = 33. xb = %d = 0, Xcb = XcD = Xc = 1-3, and cbd = 1- As indicated on the z-axis, the distance between two ticks is 10b. The dashed contour line, representing a volume fraction of approximately (p = 4x 10 , indicates the density seen hydrodynamicaUy...

For the corona contribution, some care has to be taken. In order to calculate the free energy of this part, the number of blobs has to be calculated for each morphology, taking into accotmt that the radial dependence of the density changes with the curvatore. For a completely planar surface, de Gennes and Alexander [36,37] showed that the blob size wDl be constant and scale by s, where s is the area available per chain. For a cuiwed micellar core, the surface per corona chain will naturally increase... 

In a recent work, the original Halperin and Alexander model was, in light of new experimental data, extended for the case of high cOTicentrations and particularly for the case of overlapping coronal A-chains [64]. As noted, Eq. 34 is only approximately correct and several corrections should be included. In particular, as is evident from Fig. 4, Eq. 34 does not give a complete description of the activation barrier. In addition to the surface free energy of the exposed insoluble B-block, the expulsion process involves interactions with the corona chains. The free energy of the activated state must therefore be calculated in more detail. 

In order to understand the interactions controUing the mechanisms behind self-assembly, the interaction energy between the hydrophobic core chains and the solvents as well as the corona chain length were also varied. The results show that the effect of incrementing the hydrophobic energy is threefold First, the initial nucleation-like event appears to be essentiaUy unaffected second, the time window of miceUization expands, i.e., the time for completion increases and third, the... 

Hsu, H.J., Sen, S., Pearson, R.M., Uddin, S., Krai, P., Hong, S. Poly(ethylene glycol) Corona Chain Length Controls End-Gronp-Dependent Cell Interactions of Dendron Micelles. Macromolecnles 47(19), 6911-6918 (2014). doi 10.1021/... 

The topology of the hydrophobic block is critical in the double-hydrophilic ABC terpolymers since it determines the self-assemblies in aqueous media. For instance, P2VP-PMMA-PAA, prepared by sequential monomer addition, forms now micellar self-assemblies bearing oppositely charged corona chains (P2VP, PAA). These living self-assemblies, called heteroarm star-like micelles, are sensitive to pH changes and can further associate in a second level of hierarchy. 

Polymers with a star-like topology have attracted interest for many years. The rheological behavior in the melt and in solution of starpolymers differs from the behavior of linear polymers [172]. Polystyrene starpolymers with selectively deuterated core or corona chains were investigated by SANS and it was found that the chains are more stretched within the core (or close to the branching point), while the outer parts of the chains follow the single chain behavior of linear polymers [173]. This result confirmed theoretical predictions by Daoud and Cotton [174] and Birshtein et al. [175]. A similar behavior was found for the chain conformations in star-like block copolymer ionomer micelles, which were studied by SANS, too [176]. 

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