Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1021/ma901740fAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at Nanostructure, morphology, and properties of fluorous copolymers bearing ionic grafts Tsang, Emily M. W.; Zhang, Zhaobin; Yang, Ami C. C.; Shi, Zhiqing; Peckham, Timothy J.; Narimani, Rasoul; Frisken, Barbara J.; Holdcroft, Steven http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/droits L'accès à ce site Web et l'utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D'UTILISER CE SITE WEB. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/eng/view/object/?id=952ebf60-e98f-4852-90d0-47d6b5207f18 http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/voir/objet/?id=952ebf60-e98f-4852-90d0-47d6b5207f18 Received August 4, 2009; Revised Manuscript Received November 6, 2009ABSTRACT: In order to probe the effects of polymer microstructure on the properties of proton conducting polymer membranes, three series of fluorous-ionic graft copolymers, partially sulfonated poly([vinylidene difluoride-co-chlorotrifluoroethylene]-g-styrene) [P(VDF-co-CTFE)-g-SPS], comprising controlled graft lengths and degrees of sulfonation were synthesized. The parent building block was a poly(vinylidene difluoride-co-chlorotrifluoroethylene) [P(VDF-co-CTFE)] macroinitiator (M n =3.12 Â 10 5 g/mol) synthesized to contain 1 chloro group per 17 repeat units, onto which polystyrene, having degrees of polymerization of 35, 88, and 154 units per graft, was grown by atom transfer radical polymerization (ATRP). These graft copolymers, termed short, medium, and long graft chains, were sulfonated to different extents to provide a series of polymers with varying ion exchange capacity (IEC). The resulting P(VDF-co-CTFE)-g-SPS copolymers were cast into proton exchange membranes, and their nanostructure, morphology, and properties were studied. TEM revealed that all three membrane series exhibit a...

To gain insight into the role of crystallinity and morphology on proton transport through solid polymer electrolytes, we synthesized graft copolymers, poly(vinylidene difluoride-co-chlorotrifluoroethylene)-g-polystyrene [P(VDF-co-CTFE)-g-PS], consisting of a hydrophobic, fluorous backbone and styrenic graft chain of varied length (DPstyrene = 39, 62, and 79), by graft atom transfer radical polymerization (ATRP). The polystyrene graft chains were subsequently sulfonated to different degrees to provide three series of polymers with controlled ion exchange capacity (IEC). The crystallinity and morphology of solution-cast membranes were examined by XRD and TEM, respectively. The grafting of the parent side chain is found to hinder crystallization of the fluorous backbone and the impact of the degree of sulfonation of the side chain on the crystallinity of the polymer is dependent on the graft length: No impact is found for medium and long graft lengths, but for short graft length copolymers (PS39), the degree of crystallinity in the sulfonated membranes is twice that of the unsulfonated membrane. A phase-separated morphology consisting of 2–5 (±1) nm ion-rich domains is observed for all of the graft copolymers. These graft copolymers allow access to very high IEC membranes (>3 mmol/g), which are insoluble in water. The shorter graft length series, P(VDF-co-CTFE)-g-SPS39, swells less in the intermediate IEC range (<3.0 mmol/g) because of its higher degree of crystallinity and lower PS to VDF ratio, and provides membranes with exceptionally high proton conductivity. Two graft series possessing similar weight fraction of PS but different graft density were also examined in order to evaluate the effect of graft density. It was found that lower graft density copolymers possess higher crystallinity and more contiguous PVDF domains, which allow high IEC membranes to be prepared that swell to lower extents.

To investigate relationships between morphology and proton conductivity in ionic copolymer membranes, we have studied two series of fluorous copolymers bearing polystyrene grafts sulfonated from 0 to 100%. Small-angle X-ray and neutron scattering experiments reveal a disordered, partially phase-separated system consisting of fluorous domains in a partially sulfonated polystyrene matrix with aggregation of ion-rich domains within the matrix. The size of the fluorous domains depends on graft density, and their packing depends on the graft chain length. The spacing of the ion-rich domains is remarkably independent of either graft chain length or charge content. We find that the samples with lower graft density, which are partially crystalline, develop a less-ordered morphology with a lower degree of phase separation. The partially crystalline samples swell less and have a slightly lower conductivity at similar water content; the lower conductivity is attributed to a more tortuous conducting phase.

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The role of graft and diblock ionomer architecture on the morphology and properties of ionomer/ fluoropolymer blends is examined. The graft copolymer consists of a partially fluorinated backbone of P(VDF-co-CTFE) and partially sulfonated polystyrene (PS) side chains while the diblock copolymer consists of a block of P(VDF-co-HFP) and a partially sulfonated PS block. These ionomers are blended with fluoropolymers possessing a chain length that matches the average sequence length of the fluorous block segment of the ionomer. The results from this study are surprising: graft ionomers are primarily insensitive to blending due to the incorporation of the non-ionic fluorous polymers into the domains of the perfluorinated backbone which does not deleteriously affect the interconnecting proton conducting ionic clusters. In contrast, diblock ionomers are highly sensitive to the addition of fluoropolymers and despite the observation that ionic channels are retained, water sorption is decreased due to the increased volume of the non-ionic domains, which decreases proton mobility and proton conductivity.