Synthesis Of Functional Substituted Polyacetylenes And Their Gas Permeation And Fluoride Ion Sensing Properties

The design and synthesis of substituted polyacetylenes are motivated by the development of new materials that display interesting physical and chemical properties. Incoorperation of functional groups into the polymer endows them with various functions, such as optical nonlinearity, liquid crystallinity, light emission, helical chirality, high gas permeability, and so forth. In this study, various substitued polyacetylene was synthesized and the gas permeation and ion sensing properties was investigated, the results are as follows:(1) Synthesis and gas permeation properties of polyacetylene containing biphenyl moities. Diarylacetylene monomers (la-d) containing a substituted biphenyl and silicon substituent were synthesized and then polymerized with TaCl5-n-Bu4Sn to obtain the corresponding polymers (2a,2b and2d). The resulting polymer displayed good solubility in conventional organic solvents such as toluene, CHCl3, and THF. Polymers2a and2b afforded free standing membranes by casting from their toluene solution. Desilylation of membranes2a and2b was carried out with trifluoroacetic acid to give membranes3a and3b. Thermal gravimetric analysis showed all the polymers have high thermal stability. The oxygen permeability coefficient (PO2) of the membranes is in a range from22to160barrers. The separation factors of O2against N2(PO2/PN2) of the membranes ranged from2.4-3.3, and they tended to decrease as the PO2increased.(2) Effect of aging on the gas permeation properties of PTMSDPA. Membrane of poly [1-(4-(trimethylsilyl))phenyl-2-p-phenylacetylene](PTMSDPA) was prepared through solution casting and membrane thickness was33-112μm. The effect of membrane thickness, storing temperature and storing atmosphere on membrane gas permeability was examined. The results showed that the physical aging will cause the gas permeation coefficient of membrane decreased, and this process is reversible. Storing temperature was elevated, the decreasing rate of the permeability coefficient accelerated, the thinner the thickness of the membrane,the faster the decreasing rate of gas permeability coefficient. The storing atmosphere did not affect the gas permeability changing tendency of the membrane. The decrease of gas permeability is largely due to the decrease of diffusion coefficient while the solubility coefficient was constant. (3) Synthesis and ion sensing properties of polyacetylene bearing boryl groups. Acetylenic monomer containing bis(2,4,6-trimethylphenyl)boryl moiety was synthesized and polymerized with Rh-based catalysts. The resulting polymer had good solubility in common organic solvents such as toluene, CH2Cl2, and CHCl3. The structures of monomer and corresponding polymer were characterized by1H NMR,11B NMR, and element analysis. According to thermogravimetric analysis (TG A), the onset temperature of weight loss of the polymers was250℃, which is higher than that of polyphenylacetylene. The fluorescent quantum yield of the polymer was0.324. In titration experiments, as the gradual increase of [F-], the emission intensity remarkably decreased. Stern-Volmer plots identified fluorencence signal amplification effect of the polymer in the detection of fluoride ion. Selective detection of fluorine ion was attained by the present polymer.