Poly-diacetylene crystals

Hoofman RJOM, Siebbeles LDA, de Haas MP, Hummel A, Bloor D. (1998) Anisotropy of charge-carrier mobility in poly diacetylene crystals. J Chem Phys 109 1885-1893. 

There are also macroscopic polymer single crystals [8-11], which have a tt-electron system along the polymeric carbon chains (Fig. 1.11) e.g. the poly-diacetylene crystals (Fig. 1.10). They are formed from monomeric diacetylene crystals via a so called topochemical reaction (Fig. 2.19 and Chap. 3). Topochemical refers to reactions of molecules in crystals in which the reactivity of the molecules is less important than... 

An interesting special case of crystal growth from solution are the macroscopic polymer single crystals of diacetylenene, the poly-diacetylene crystals. For their preparation, as a first step, macroscopic molecular crystals of substituted diacety-... 

Fig. 3.13 Projections of the TS-diacetylene monomers (above) and polymers (below) onto the plane of the polymer backbone in the poly-diacetylene crystal. The lattice constant b of the monomer crystal and the polymer crystal differ by only 0.2 A. Therefore, the crystal is not destroyed by the polymerisation the macroscopic polymer crystal is formed from the macroscopic monomer crystal [13].

A growing number of reports are appearxng concerning %<3) of materials as determined by THG experiments. Among organics a variety of poly(diacetylenes), e. g., 4-BCMU (4-butoxycarbonylmethylurethane polydiacetylene) (15,109) have been studied as pure materials and as LB films, 110) Crystalline films of poly(4-BCMU) in the red form, were found to have higher %<3) than amorphous films, attributed to the orientational effect of crystallization.(109) The blue form also has been studied. 111) Maximum values of %<3) reported to date are 1 x 10 10 esu at 1.3 l. Poly (phenylacetylene) THG at 1.06 lhas recently been measured. 111) The 2- and 3-photon resonance enhanced value of %<3) determined is 7 x 10 12 esu. 

Fig. 32 (a) Topochemical polymerization mechanism for a typical diacetylene monomer, (b) Crystal structure of a typical poly diacetylene... 

D. Bloor and R. Chance, (Eds.) Poly diacetylenes, NATO ASI Series E012, (Mar-tinus Najhoff, Dordrecht, The Netherlands, 1985) D.J. Sandman, (Ed.) Crystal-lographically Ordered Polymers, ACS Symposium Series 337 (ACS, Washington, D.C. 1987). 

Poly diacetylenes. The polydiacetylenes (PDA s) are unique among highly conducting polymers discovered in the past years in that they can be obtained as highly perfect macroscopic single crystals.68 Upon solid-state polymerization of... 

Fully conjugated and fully chain-aligned polymer single crystals with planar polymer backbone are obtained, which may have the alternative acetylene (ynene) or butatriene structures of Eq. (1). From our experiment we know that the acetylene structure is dominant in the polymer molecules. Up to now the best investigated diacetylene crystals are the TS-6 monomer crystals and the corresponding polymer crystals (poly TS-6). The substituents R and the notation of further diacetylene crystals discussed below are listed in Table 1. 

Some simple fluorescence decay laws are given which result from models concerned with relaxation phenomena, heterogeneity, molecular motion and excitation migration in synthetic polymers exhibiting fluorescence. Application of such laws to decays from a poly (diacetylene) in rigid crystal form to polystyrene in fluid solution, and to vinyl naphthalene co-polymers in fluid solution are considered briefly. 

Fig. 1.10 The crystal structure of macroscopic poly-diacetylene paratoluylsulfonyl-...

The solid-state polymerisation of the diacetylenes can be initiated thermally and/or through irradiation with UV or y radiation and leads for many substituents R to macroscopic poly-diacetylene single crystals. For most substituents R, it is irreversible. Table 2.5 gives a selection of substituents R with which macroscopic diacetylene crystals have been successfully grown. Additional examples can be found in Enkelmann [11]. 

Some substimted diacetylenes (R-C=C-CMI -R, hereinafter referred to as DA) constitute a class of crystals polymerizable in the solid state [1]. One may thus obtain large single crystals, built of poly diacetylene (PDA) chains parallel to one another. A pronounced anisotropy of the systems, due to the presence of long TC-conjugated chains, resulted in an interest concerning electrical and opticd properties of DA [2,3]. Much less attention has been paid to studies of their dielectric properties [4-6]. 

Thakur and Meyler [22] have reported the growth of thin-film single crystals of poly(diacetylenes) by a shear process that produces aligned areas of about 1 cm-from melts and about 50 mm- from solution. These thin-film crystals were reported to be four orders of magnitude larger than those previously prepared by Isoda [23]. 

Tokarski, Z., Epling, B., Natarajan, L. V., Cooper, T. M., Grinstead, T. M., Crane, R. L., and Adams, W. W., The nonlinear optical response of corona poled poly[(gamma-A-pentylamino-p-nitrobenzene) L-glutamate], Polym. Prepr., 34, 600-601 (1993). Thakur, M., and Meyler, S., Growth of large-area thin-film single crystals of poly(diacetylenes), Macromolecules, 18, 2341-2344 (1985). 

The poly diacetylene single crystals are fiber-like with high aspect ratio. 

Macro Crystals.—Nearly defect-free crystals of polymers have been produced by direct polymerization of monomer at gas-solid or liquid-solid interface. Poly-(diacetylene) single crystals have been produced from irradiation of the crystalline monomer and involves the instantaneous polymerization and crystallization of... 

In contrast to poly(acetylene), poly(diacetylene)s have limited electrical conductivity (<0.1 S/cm), but can be obtained as large, single crystals. 

The polymerization of diacetylene is an example of a topochemical polymerization in which 1,4-addition of 1,3-diyne units takes place in the crystalline state. The reaction does not require a catalysts and is performed by irradiation of the diacetylene crystals with visible or UV light, X-rays, y-rays, or by annealing the crystals below their melting point. The unreacted monomer is then extracted with a suitable solvent (e.g., hexane, toluene), leaving a single, dark red crystal of poly (diacetylene). This unique polymerization process was already observed in 1882 [47] and has now been intensively studied [48]. A correct interpretation of the phenomena was first provided in the early 1970s [13-15,49]. 

Le Moigne, J., Kajzar, R, and Thierry, A., Single orientation in poly(diacetylene) films for nonlinear optics. Molecular epitaxy of l,6-bis(9-carbazolyl)-2,4-hexayne on organic crystals. 

---