Oriented Poly(dialkylstannane)s

Abstract

The inorganic (or ‘organometallic’) polymers poly(dibutylstannane), poly(dioctylstannane), and poly(didodecylstannane) have been oriented by shear forces, the tensile drawing of blends with polyethylene, and deposition from solution onto glass slides coated with an oriented, friction‐deposited poly(tetrafluoroethylene) (PTFE) layer. Orientation of the polystannanes has been examined by polarization microscopy, UV‐vis spectroscopy with polarized light, and X‐ray diffraction and their direction is found to depend on the length of the alkyl side groups and the method of orientation. Remarkably, in some cases the polystannane backbones are oriented parallel and in other instances perpendicular to the direction of the external orientation stimuli. The latter structural arrangement is most conspicuous for polymers substituted with dodecyl side groups, which are found to align parallel to the applied orientation direction, which forces the polymer backbone into a perpendicular position. Finally, UV‐vis spectra indicate that changes in the backbone conformation of certain polystannanes might be induced by applying mechanical stress.

Light‐Stability of Poly(dialkylstannane)s

“…[9,10,16,25] These powders were found to be oxidized (oxygen contents 4.9-8.5% w/w) and their chemical composition (Table 2), as well as their transition temperatures observed in DSC (Table 3) did not differ significantly from those of the above described degradation products of the same polymers exposed to ambient in solution. Assuming that in the elemental analysis the supplementation of the masses of C, H, and O to 100% is due to tin, oxygen/tin ratios of 1.29-1.54 and alkyl/tin ratios of 1.86-1.97 were obtained for the decomposition products (in bulk or solution) of all polystannanes, indicating that similar products were formed in all cases, in agreement with the observation that only one signal emerged in 119 Sn NMR spectra around -175 ppm (in deuterated 1,2-dichlorobenzene at 100 8C), also in all cases.…”

“…Note that the molar mass of polystannanes might decrease somewhat upon redissolution, [10] and accordingly a moderate difference in the degradation rate might result upon exposure of solutions containing in situ synthesized or redissolved polystannanes; see, for instance, the stability factors F in Table 4 and 5 for the degradation of poly(dibutylstannane) in CH 2 Cl 2 according to both methods, where F amounted to 0.43 and 0.57, respectively. It should be noted that poly(dialkylstannane)s exhibit a strong UV absorption band with an absorption maximum in the region of 370-410 nm, [7,9,13,14,[16][17][18][19] which presumably arises from the delocalization of s-electrons of the tin atoms along the polymer backbone. In several reports, this band was used for the analysis of the degree of degradation of polystannanes.…”

From poly(dialkylstannane)s to poly(diarylstannane)s: comparison of synthesis methods and resulting polymers

“…in the range convenient for polystannanes. [16,34] UV-vis absorption spectra reveal that phenyl groups induce a bathochromic shift of the wavelength at maximum absorbance (Table 3 and Fig. 5), which might be associated with increasing delocalization of electrons with increasing number of aromatic groups in the polymer.…”

Poly(di(ω-alkylphenyl)stannane)s

“…Remarkably, these polymers at room temperature are in liquid-crystalline state, which facilitates orientation of them by simple methods such as tensile deformation, shearing or crystallization on oriented substrates [15].…”

“…P(D4ØSn) was only weakly birefringent. P(D2ØSn) and P(D3ØSn) could easily be oriented by shearing of bulk samples above T g on a glass slide with a razor blade, analogous to poly(dialkylstannane)s [12,15] as indicated by the pronounced birefringence observed between crossed polarizers in an optical microscope. Persistent orientation, induced by shearing could not be achived for P(D4ØSn).…”