Preparation And Thermo-optic Properties Of The Side-chain Optically Activity Polymers

Optically active polymers have a special helical structure and been widely used in sensing specific molecules,chiral recognition,asymmetric catalysis and optical fields.Therefore,optically polymers have attracted increasing interest in the fields of novel polymer material research.In this paper,three kinds of side-chain optically active polymers with different structures were synthesized,which were poly(triphenylmethyl methacrylate)(PTrMA)and polymethacryloyl(S)-(-)-binaphthol(P[MA-BINOL])and maleic anhydride cholesterol ester-methyl methacrylate copolymer(Poly[Chol-MA-co-MMA]).The study emphases were the effect of different side-chains structure on the whole structure,thermodynamic behavior and thermo-optic properties of optically active polymers.The structure and properties of target optically active polymers were characterized by the fourier transform infrared(FTIR),~1H nuclear magnetic resonance(~1H-NMR),polarized light microscopy(POM),differential scanning calorimetry(DSC),thermal gravimetric analysis(TGA),circular dichroism(CD)and X-ray diffraction(XRD).The optimal preparation conditions of three optically activity polymers were determined.The main researches were as followings:(1)The optically active polymer of PTrMA was synthesized by liquid crystal template method using triphenylmethyl methacrylate(TrMA).The molecular flexibility of PTrMA was improved by adding different proportions of methyl methacrylate(MMA).The results showed that the glass transition temperature of PTrMA was 151°C,and the decomposition initiation temperature was 219°C.With the continuous addition of MMA,the absorption peak shifted to the left in the DSC curve,which proved that the glass transition temperature of PTrMA was reduced,and the thermal stability was improved.XRD results showed that MMA had no effect on the crystal structure of PTrMA.However,with the amount of MMA increasing,the degree of crystallinity of the copolymer continued to decrease.PTrMA showed obvious CD signal peaks at 204 nm,212 nm and 219 nm,namely the Coton effect,indicating that PTrMA formed a chiral helical structure at the segment level and had optical rotation.Triphenylmethyl methacrylate-methyl methacrylate copolymer(Poly[TrMA-co-MMA])had obvious thermal rotation characteristics,and the thermal-optic properties were more and more stable with the decreasing of temperature rate.(2)The preparation method of P[MA-BINOL]optically active polymer is as follows:Firstly,P[MA-BINOL]optically active polymers were synthesized by one-step method and two-step method,respectively.Secondly,polymer network cholesteric liquid crystal(PNCLCs)films with helical structure were prepared from RM257.Finally,using PNCLCs as a template,P[MA-BINOL]was introduced into the template to obtain a novel optically active polymer composite film.The results showed that methacryloyl(S)-(-)-binaphthol(MA-BINOL)and its polymers were all optically active materials.With the increasing of temperature,the P[MA-BINOL]composite film had a decreasing tendency in optical rotation.The light intensity was gradually reduced,which had thermal rotation properties.(3)Poly[Chol-MA-co-MMA]optically active polymer was synthesized by thermal polymerization from Chol-MA and MMA.The results showed that the target polymer was synthesized successfully.POM analysis indicated that Chol-MA was a kind of cholesteric liquid crystal polymer.Poly[Chol-MA-co-MMA]showed the texture of focal conic was observed during heating,which indicated that Poly[Chol-MA-co-MMA]was a thermotropic cholesteric liquid crystal polymer.With the introducing of MMA flexible chain,there was a phenomenon of changing from positive and negative Corton effect to almost negative Corton effect in the CD map,which proved that the flexible segment had a large helical arrangement of polymer molecules.It could be obtained that both Chol-MA and its copolymers had thermal-optic properties by self-made thermo-optic performance system.