Polymerization of styrene in polyelectrolyte-surfactant films


Edler, K. and Jaber, R., 2012. Polymerization of styrene in polyelectrolyte-surfactant films. In: Polymer Networks Group Meeting 2012, 2012-08-12 - 2012-08-16.

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Nanostructured polyelectrolyte films self-assemble at the air/solution interface1,2 via interactions between water-soluble neutral polymers with polarisable groups, and surfactant micelles with a positive charge.3 The film structure consists of ordered arrays of surfactant micelles encapsulated in a hydrogel matrix and spray coating of the same multicomponent aqueous solutions onto solid substrates results in similar mesostructured hydrogel coatings. Here we exploit the mesostructures in these films as templates for polymerization of styrene. The replication of ordered surfactant liquid crystalline structures into mechanically and chemically stable nanostructured polymer materials could provide a rapid, cheap method to generate intricate nanostructures. The ability to generate such materials from generic polymers would open up new means to create chemically and electroactive responsive supports, porous materials for catalysis, nanofiltration, and allow creation of new nanocomposites with improved properties such as ductility and stress dissipation. While direct micelle templating has been achieved for inorganic materials such as silica, for polymers this has proved more difficult since the time scales for the polymerisation reaction are generally slower than the rate of micelle re-arrangement through interdroplet diffusion and droplet exchange,4 resulting in phase segregation of the polymer from the micellar structures. Figure 1: Grazing incidence x-ray diffraction patterns of a PEI film incorporating 0.05M CpB, 0.09M styrene and 0.1mM of ACHN at 25C° (A) before, (B) after 1.6hr UV irradiation at 254nm. GPC demonstrates that polystryrene is formed in the films. In our films, the high viscosity of the hydrogel surrounding the swollen surfactant micelles prevents micelle rearrangement on short timescales, making them an ideal host for the polymerisation of hydrophobic monomers to create solid polymer nanostructures within the water-soluble polymer film. The polymer networks will reinforce the film making it more robust. Experiments on encapsulation of hydrophobic species5 demonstrate that the organized nanostructures within our polyethylenimine (PEI)-surfactant films can be swollen with monomer. Four C16 tail surfactants, with either aromatic headgroups, (benzyldimethylhexadecylammonium bromide (BDAB), hexadecylpyridinium bromide (CpB)) or non-aromatic headgroups, (hexadecyltrimethylammonium bromide (CTAB), hexadecyltriethylammonium bromide (CTEAB)) have been used to study the encapsulation of styrene into our PEI films. Neutron reflectivity was used to probe film structure and location of styrene, and showed that styrene was most effectively encapsulated in films prepared from CpB and BDAB. In situ polymerisation of the encapsulated styrene in PEI films was then studied. Initiation of polymerisation using a UV-activated free-radical initiator, ACHN, produced more well-ordered mesostructures, than those from thermal initiation. The formation of polystyrene has been characterized by GPC, FTIR and SAXS after removal of the templating hydrogel. The effect of UV exposure time, surfactant template, styrene and initiator concentration on the generation of well-ordered mesostructures in this system and the molecular weight and nanostructure of the polymer produced will be reported. References 1) KJ Edler, A Goldar, T Brennan, S Roser Chem. Commun. 2003, 1724. 2) BMD O'Driscoll, E Milsom, C FernandezMartin, L White, S Roser, KJ Edler Macromol 2005 38 8785. 3) BMD O'Driscoll, C Fernandez-Martin, R Wilson, S Roser, KJ Edler J Phys Chem B 2006, 110,5330 4) F. Yan and J. Texter, Adv. Colloid Interface Sci., 2006, 128-130, 27-35. 5) B.M. D. O'Driscoll, A. M. Hawley and K. J. Edler, J. Colloid Interface Sci., 2008, 317, 585-592


Item Type Conference or Workshop Items (Paper)
CreatorsEdler, K.and Jaber, R.
DepartmentsFaculty of Science > Chemistry
Research CentresCentre for Sustainable Chemical Technologies
ID Code34284


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