Grafting Of Polyacetylenes And Synthesis Of Side-on-fixed Polyacetylenes Containing Terphenyl Mesogens As Pendants

Functional polyacetylenes are a material of polymer,their compsition is a polyene chian and the funcational groups.The structure endow potential applications in biological sensors,solar batteries,secondary batteries,artificial muscles,diodes, radar concealed material.The new PAs with appropriate backbone-pandant combinations show various functional porperties such as liquid crystallinity, photoconduactivity,lightemission,photoresistance,helicalchirality,self-assembly, cytocompatibility,and bioactivity and so on.Novel cylindrical polymer brushes consisting of poly(diphenylacetylene) main chain and poly(poly(ethylene glycol) methyl ether monomethacrylate)(PPEGMA) side chains were synthesized by the diphenylacetylene macromonomer or side chain initiated atom transfer radical polymerization(ATRP) of poly(ethylene glycol) methyl ether monomethacrylate(PEGMA) from an bromo isobutyryl-bearing poly(diphenylacetylene)(poly(BrDPA)) method.The diphenylacetylene macromonomer,namely,DPA-PPEGMA,were prepared by the ATRP of PEGMA from bromo isobutyryl-bearing diphenylacetylene.DPA-PPEGMA was polymerized successfully with WCl₆-Ph₄Sn catalyst to give high molecular weight polymer brushes poly(DPA-PPEGMA).Meanwhile,polymer brushes(PDPA-g-PPEGMA) were obtained by ATRP of PEGMA from poly(BrDPA).The molecular weight of the side chains of PPEGMA could be controlled simply by modulating the ATRP time. The macromonomer and polymer brushes are soluble in nonpolar solvents such as toluene and chloroform.The polymers of poly(BrDPA) and poly(DPA-PPEGMA) absorb in the longer wavelength region,with two peaks at around 370 and 414 nm. The polymers are thermally stable and exhibit double crystallization and melting peaks during the cooling and heating scans.Liquid-crystalline,side-on-fixed monosubstituted polyacetylenes containing lateral pendants of terphenyl mesogens with flexible spacers and alkoxy tail were synthesized,and the effects of the backbone structure and alkoxy tails on the properties of the polymers were investigated.The structures and properties of the monosubstituted polyacetylenes were characterized and evaluated with nuclear magnetic resonance,infrared spectroscopy,thermogravimetry,differential scanning calorimetry,polarized optical microscopy,ultraviolet spectroscopy,and photoluminescence analyses.The molecular weights of the polymers were measured by gel permeation chromatography.The monomers form smectic A phases.However, The P(1) could not exhibit liquid crystallinity at elevated temperatures.The steric effect of bulky,liquid-crystalline mesogens and a direct connection with the main chain prevented the planar conformation of the polyene backbone and,therefore,led to the lower absorption and emission wavelength of the polymers.