Hairy-rod polymers

A unique but widely studied polymeric LB system are the polyglutamates or hairy rod polymers. These polymers have a hydrophilic rod of helical polyglutamate with hydrophobic alkyl side chains. Their rigidity and amphiphilic-ity imparts order (lyotropic and thermotropic) in LB films and they take on a F-type stmcture such as that illustrated in Fig. XV-16 [182]. These LB films are useful for waveguides, photoresists, and chemical sensors. LB films of these polymers are very thermally stable, as was indicated by the lack of interdiffusion up to 414 K shown by neutron reflectivity of alternating hydrogenated and deuterated layers [183]. AFM measurements have shown that these films take on different stmctures if directly deposited onto silicon or onto LB films of cadmium arachidate [184]. 

Fig. 7.23 Self-assembled hairy-rod polymers based on metal coordination and ionic interaction.

Wiegand, G., Jaworek, T., Wegner, G., and Sackmann, E. Heterogeneous Surfaces of Structured Hairy-Rod Polymer Film Preparation and Methods of Functionalization. Langmuir 13, 3563 (1997). 

In regards to the intermolecular self-organization much can be learned from the physics of hairy-rod polymers [60] and PFs, especially PF2/6, are excellent model systems. As is the case in diblock polymers, a deceptively simple model parameterization of the key underlying interactions yields semi-quantitative predictions of the structural phase behavior. These model calculations can be directly compared to the experimental phenomena. The... 

Fig. 13 Above Schematics of a hairy-rod polymer consisting of a stiff backbone and flexible covalently connected side chains. N, Zk, and v are the number of segments, the segment length (the Kuhn length), and the volume of the beds of the side chains, respectively M, Zu, L, and d are the number of the repeat units, distance between grafting points (the unit length) and the length and diameter of the rod, respectively. Below. End-on schematics of (a) nematic (Nem) and (b) hexagonal (Hex) phase of hairy-rod molecules. Adapted from [24]...

Stepanyan, R., A. Subbotin, M. Knaapila, O. Ikkala, and G. ten Brinke. 2003. Self-organization of Hairy-rod polymers. Macromolecules 3760. 

Vierheller T R, Forster M D, Schmidt A, Mathauer K, KnoU W, Wegner G, Satija S and Majkrzak C F (1994) Structure and thermal-stability of Langmuir-Blodgett-Kuhn layers of hairy-rod polymers probed with neutron and X-ray reflectometry, Macromolecules 27 6893-6902. 

Fig. 31. Concepts to increase the planarity of hairy-rod polymers to be ladder like upon formation of hydrogen bonds. Adapted from D. A. P. Delnoye, R. P. Sijbesma, J. A. J. M. Vekemans, and E. W. Meijer, J. Am. Chem. Soc. 118, 8717 (19%) M. Moroni, J. Le Moigne, T. A Pham, and J.-Y. Bigot, Macmmolecules 30,1964 (1997).

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