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Polyamphiphiles of the type poly(ω-dimethylaminopyridinium bromide alkyl methacrylate)s with octyl, dodecyl, and hexadecyl spacers were synthesized and further self-assembled with octylsulfonate to form stoichiometric complexes. The thermal and structural properties of both the bromine- and octylsulfonate-neutralized series (PnDMAP-Br and PnDMAP-S8, n = 8, 12, 16) were investigated in the bulk. For n = 8 in both series and n = 12 in the Br series, the materials are essentially amorphous with weak mesomorphic order. For n = 12 in the S8 series and n = 16 in both series, crystalline and disordered lamellar (smectic A) structural order is observed. Recrystallization is slow after melting, especially for P16DMAP-S8, which can be maintained indefinitely in its liquid crystal state even well above room temperature. This is attributed to the ionic interactions coupled with the polymeric character of the materials as well as, possibly, surfactant chain and polyamphiphile spacer interactions in the complexes. The ...

A methylpyridinium tail-end polyamphiphile with a 12-methylene spacer was complexed with n-alkyl sulfonate surfactants of 4, 8, and 16 carbon lengths. The thermal and structural properties of these poly(12-methacryloyloxydodecyl-4-methylpyridinium sulfonate)s in the solid state were studied. The complexes with the two shorter surfactants self-assemble into a disordered lamellar-like morphology, with relatively short correlation lengths, similar to the parent Br-neutralized homopolymer. Two glass transition-like events are observed in the DSC thermograms and are ascribed to nanophase-separated nonionic and ionic subplanes, respectively. The complex with the longest surfactant displays thermotropic liquid crystalline behavior, with transitions between two different partially crystalline phases (related to surfactant tail-end crystallization), a smectic A-like mesophase, and the isotropic phase. Surprisingly, the lamellar spacings for all of the complexes are very similar to that of the parent polymer. Two possible structural models taking this into account are discussed.

A simple synthetic route to a new poly(diallylammonium) salt functionalized by a styrene group is presented. This reactive polymer was employed for polyelectrolyte multilayer films using electrostatical layer-by-layer self-assembly, together with an inorganic polyanion, namely an exfoliated hectorite clay. To enhance their stability, the final hybrid multilayers were cross-linked by exposure to UV light, leading only to a minor shrinkage. Alternatively, the reactive polycation was cross-linked after each adsorption step. X-ray reflectometry revealed that the two types of films dispose of an internal order with a short length scale, that seems insensitive to the photo-cross-linking. Cross-linking after each adsorption step, however, results in more regular film growth, and reduces the films' roughness and the amount of polyanion deposited. Under these conditions, the films seem to grow by deposition of submonolayers with a combined vertical and lateral expansion, resulting in the self-healing of previously deposited, incomplete layers.

A series of homologous statistical polymethacrylate comb copolymers with tail-end 4-(dimethylamino)pyridinium ionic groups were synthesized by partial quaternization of high molar mass poly(12-bromododecyl methacrylate). The copolymers of lower ion content are found to be biphasic by differential scanning calorimetry, resembling classical ionomers, with a lower glass transition temperature (Tg) that remains constant up to about 20 mol % ion content before increasing and a higher Tg that increases monotonically with ion content. X-ray analysis indicates the presence of a soft phase with an invariant microstructure for all of the copolymers, whereas the hard-phase microstructure, considered to be a disordered partial bilayer in the ionic homopolymer, is characterized by an increasing long period with decreasing ion content. Models to reconcile the various data are proposed, which show how large amounts of nonionic units can be incorporated into the hard-phase microstructure, with the invariant soft-phase microstructure also rationalized. This copolymer series thus bridges ionomer and mesomorphic polysoap characteristics by the presence of two phases whose relative proportions vary with ion content, both of which possess their own (short-range) microstructure that determines the nature of their evolution with copolymer composition.

The synthesis of a new series of cationic tail-end polyamphiphiles of the type, poly(ω-pyridinium alkyl methacrylate)s with various 4-substituted pyridinium bromide groups and with spacers of 8, 12, and 16 methylene units, obtained by free radical polymerization in aqueous micellar solution, is described, and the thermal and structural characteristics in the solid-state have been studied. All of the polymers show a single glass transition in the range 39−105 °C, whose value depends strongly both on the spacer length, due to internal plasticization, and on the specific nature of the pyridinium moiety, where higher Tg's can be related to greater rigidity of the pyridinium group. The polymers are all birefringent between crossed polarizers, in some cases up to their degradation temperatures. X-ray diffraction investigations indicate that they tend to self-organize into an amorphous lamellar morphology that appears to be better defined the longer the alkyl spacer and whose details depend also on the specific ...