PSSNa

Salt effects in polyelectrolyte block copolymer micelles are particularly pronounced because the polyelectrolyte chains are closely assembled in the micellar shell [217]. The situation is quite reminiscent of tethered polymer brushes, to which polyelectrolyte block copolymer micelles have been compared, as summarized in the review of Forster [15]. The analogy to polyelectrolyte brushes was investigated by Guenoun in the study of the behavior of a free-standing film drawn from a PtBS-PSSNa-solution [218] and by Hari-haran et al., who studied the absorbed layer thickness of PtBS-PSSNa block copolymers onto latex particles [219,220]. When the salt concentration exceeded a certain limit, a weak decrease in the layer thickness with increasing salt concentration was observed. Similar results have been obtained by Tauer et al. on electrosterically stabilized latex particles [221]. 

So, the PVA/poly(sodium styrene sulphonate) [PSSNa] blend was obtained by casting aqueous solution of polymers mixture (PVA with Mw= 124,000-186,000 and HD=99% and PSSNa with Mw= 70,000). The resulted films were crosslinked with 1,2-dibromethane in gaseous phase. A semi-interpenetrating network (SIPN) in which polyelectrolyte (PSSNa) chains are trapped inside a based PVA network was obtained [44], A totally miscible blend with a very good film clarity and high mechanical resistance [44] resulted. 

The PVA/PSSNa membranes evidence a high permselectivity, comparable with the one of commercial ion exchange membrane as it can see in table 14, where were presented the permeability coefficient (P) and the ratio P to D (diffusion coefficient) that express the effect of porosity and of the electrolyte exclusion. 

Table 14. Diffusion of sodium chloride at 25 °C through a PVA/PSSNa membrane (Na+ form) [18,44]...

The PVA/PDMeDMPCl blend membranes evidenced a lower permselectivity than PVA/PSSNa membranes, probably because of a possible phases separation during the solvent evaporation, as it can see from table 15 [44],... 

Fig. 3 FTIR spectra of monomer EDOT and polymer PEDOT in the presence of PSSNa. (Reprinted with permission from Bruno et al. [37]. 2006, American Chemical Society)...

Fig. 7 Atomic force microscopy pictures obtained from a PEDOT/PSSNa film (6p X 6p) synthesized at an EDOT to PSSNa ratio of 1 1. (Reprinted with permission from Rumbau et al. [43].

The effect of concentration of the redox mediator on the formation of PEDOT/PSSNa was studied by these researchers by varying the concentration of terthiophene (0.025-1%) in a series of reactions. At least 0.5% (by weight of monomer concentration) of the terthiophene was observed to be required to initiate the polymerization of EDOT using SBP (Fig. 8). PEDOT/PSSNa was not formed when the concentration of terthiophene was 0.025%. The polymerization was also performed at various pH conditions, and the concentration of the final polymer was monitored spectroscopically, as shown in Fig. 8b. It could also be observed that the... 

The FTIR spectrum of the commercially available PEDOT/PSSNa and the enzymatically synthesized PEDOT/PSSNa were compared (Pig. 9). The spectra are scaled individually for clearer comparison. The vibrations at 1195, 1139, and 1089 cm are due to the C-O-C bond stretch in the ethylenedioxy group. The peak at 1521 cm is due to the ring stretching of the thiophene ring. The weak vibration at 1062 cm is possibly due to the C-O stretch. Peaks at 979, 937, and 840 cm are assigned to thiophene C-S bond stretching. As seen in Pig. 3, the PEDOT/PSSNa synthesized enzymatically shows similar features to those of the standard, and no major additional peaks are observed. 

Systematic studies on micellar size and structure have been published for poly(styrene-h-acrylic acid) (PS-PAAc) [7, 8], poly(styrene-fr-sodium acrylate) (PS-PAAcNa) [9], or quaternized poly(styrene-h-4-vinyl-pyridine) (PS-P4VPMeI) [10, 11]. It was concluded that the polyelectrolyte chains in the micellar corona are almost fully stretched [8]. The effect of salt concentration was investigated by Guenoun et al. on poly(f-butylstyrene-fr-sodium styrene sulfonate) (PtBS-PSSNa) who observed a weak decrease of micellar size and aggregation number when the salt concentration was increased beyond 0.01 mol/1 [12]. Using small-angle neutron scattering (SANS), the authors could provide additional support for the rod-like conformation of the polyelectrolyte chains in the micellar corona [13]. 

It was already noted in previous studies, that added salt affects the micellar structure only above a certain value of the salt concentration cs. In studies of PtBS-PSSNa block copolymers a dependence of the brush dimension on the added salt concentration appeared above cs=0.01 mol/1. The thickness of a free-standing black films drawn from a diblock polyelectrolyte solution exhibited a steady drop above ionic strengths of 0.2 mol/1 [39]. 

This is confirmed by electron-microscopic and hydrodynamic data. Electron-microscopic investigations of the morphology of PSSNa-PVBTACl complexes4,32) have shown that the complexes have a globular structure with spherical particles of a narrow size distribution ranging from 20 to 40 nm. 

Fig. 10. Dependence of the degree of conversion 0 at pH 8.4 of the copolyelectrolyte - PDMAEM reaction on the molar fraction of nonionic links, in the copolymer for SSNa/MMA-PDMAEM (1), DMAEM/DTMLG-PSSNa (2) and SSNa/DTMLG-PDMAEM (3) systems62 ...

PSSNa poly(sodium styrene anhydride and monomethyl... 

Fig. 28 Layer thickness increase due to formation of a PEL-PEL complex during exposure of a MePVP brush to a PSSNa solution or a PMAA solution. Lines are a guide to the...

In preliminary experiments on the formation of polyelectrolyte multilayers deposition of a MePVP/PSSNa multilayer system and a MePVP/PMAA multilayer system were carried out using systems such as those described above. The results of this study are shown in Figure 29 and Figure 30. The prior shows the results of experiments in which two strong polyelectrolytes were used (Fig. 29). It can be easily be seen that the thickness increase due to absorption of the second layer is larger than that of the following layers deposited on top of it, but starting from the third layer the thickness increases only by about 0.5 nm per deposition cycle (i.e. deposition of two monolayers) and a linear relationship between the layer thickness and the number of deposited layers is observed. In this system the increase in layer thickness per deposition cycle is independent of the properties of the brush. 

Other teams worked on the functionalization of the aminoxyl group situated at the co position. For instance, the method of Ding et al. [342] is original for the synthesis of a novel series of poly(sodium styrenesulfonate) (PSSNa) macromonomers (compound 3 in Scheme 74) based on stable free radical polymerization in the presence of TEMPO. 

The (PSSNa) macromonomer was then copolymerized with styrene by emulsion polymerization to yield proton exchange membranes with sodium ions. The original structure of these graft copolymers (i.e., hydrophilic part owing to PSSNa) affords good ionic conductivity and may become a good model of NAFION membranes. 

Methyl methacrylate (MMA) and sodium styrene sulfonate (SSNa) are water-soluble. These polymers behave like a low MW surfactant as they form micelles in aqueous solution in which the hydrophobic part is directed towards the centre and the hydrophilic part is situated on the periphery of the micelle. Owing to such features, amphiphilic block copolymers have wide-ranging applications in drugs, pharmaceuticals, coatings, cosmetics and paints. They also exhibit very high antibacterial activities. Oikonomou and co-workers used ATRP to prepare amphiphilic block copolymers, consisting of polymethyl methacrylate (PMMA) and poly (sodium styrene sulfonate) (PSSNa) blocks [18]. The synthesis methods are described below. 

Block copolymers are synthesised with PSSNa and PMMA macroinitiators as the starting material. 

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