Large nonlinear optical(NLO) coefficient and good stability, two essential factors to evaluate second-order NLO materials, are difficult to be achieved in one molecule simultaneously. Herein, by utilizing the concept ...Large nonlinear optical(NLO) coefficient and good stability, two essential factors to evaluate second-order NLO materials, are difficult to be achieved in one molecule simultaneously. Herein, by utilizing the concept of "isolation chromophore", "isolation group" and dendritic structure, a dendritic molecule D-NS and a dendronized hyperbranched polymer DHP-NS are prepared to investigate their structure-property relationship. For the small dendritic molecule D-NS, it exhibits a high d33 value of 140 pm/V.But this value can be easily dropped when the temperature is higher than 50 °C, which extremely limits its real application. After introducing D-NS into a dendronized hyperbranched polymer chains, the obtained DHP-NS also shows a high d33 value of101 pm/V, but much better stability than D-NS. Even when its thin film was heated to 120 °C, no obvious decay can be observed in the d33 value of DHP-NS. This work demonstrates an effective strategy to realize both large NLO effect and good stability simultaneously.展开更多
Photoreactive and degradable hyperbranched （HB） copolymers with various 3,4-dihydroxycinnamic acid （DHCA） compositions, poly（e-caprolactone）-co-poly（3,4-dihydroxycinnamic acid） （PCL-co-PDHCA）, were ob- taine...Photoreactive and degradable hyperbranched （HB） copolymers with various 3,4-dihydroxycinnamic acid （DHCA） compositions, poly（e-caprolactone）-co-poly（3,4-dihydroxycinnamic acid） （PCL-co-PDHCA）, were ob- tained by thermal melt-polycondensation of PCL and DHCA. The HB structures and the branching degree （BD） of the PCL-co-PDHCA copolymers were confirmed by Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance （1H NMR）. The melting points （Tm） of the PCL-co-PDHCA copolymers changed depending on the PCL and DHCA composition by differential scanning calorimetry （DSC） measurements. Wide angle X-ray dif- fraction （WXRD） analysis showed semi-crystalline of the PCL and PCL-co-PDHCA polymers. The PCL-co-PDHCA copolymers showed good photoreactivities and fluorescent properties. Crosslinking of the cin- namoyl groups in the copolymers caused by UV irradiation affected the thermal stability and wettability slightly. Moreover, the hydrolysis experiments revealed that copolyrners are facile degradable.展开更多
基金supported by the Startup Research Fund of Zhengzhou University(1411320006)the National Natural Science Foundation of China(21325416,21274133)
文摘Large nonlinear optical(NLO) coefficient and good stability, two essential factors to evaluate second-order NLO materials, are difficult to be achieved in one molecule simultaneously. Herein, by utilizing the concept of "isolation chromophore", "isolation group" and dendritic structure, a dendritic molecule D-NS and a dendronized hyperbranched polymer DHP-NS are prepared to investigate their structure-property relationship. For the small dendritic molecule D-NS, it exhibits a high d33 value of 140 pm/V.But this value can be easily dropped when the temperature is higher than 50 °C, which extremely limits its real application. After introducing D-NS into a dendronized hyperbranched polymer chains, the obtained DHP-NS also shows a high d33 value of101 pm/V, but much better stability than D-NS. Even when its thin film was heated to 120 °C, no obvious decay can be observed in the d33 value of DHP-NS. This work demonstrates an effective strategy to realize both large NLO effect and good stability simultaneously.
基金The authors would like to thank the National NaturalScience Foundation of China （Nos. 51173072, 21004029, 51003042）, Research and Innovation Pro- gram for Graduate Colleges and Universities （No. CX10B_225Z） and State Key Laboratory of Molecular Engineering of Polymers （Fudan University, K2011-08） for financially supporting this research.
文摘Photoreactive and degradable hyperbranched （HB） copolymers with various 3,4-dihydroxycinnamic acid （DHCA） compositions, poly（e-caprolactone）-co-poly（3,4-dihydroxycinnamic acid） （PCL-co-PDHCA）, were ob- tained by thermal melt-polycondensation of PCL and DHCA. The HB structures and the branching degree （BD） of the PCL-co-PDHCA copolymers were confirmed by Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance （1H NMR）. The melting points （Tm） of the PCL-co-PDHCA copolymers changed depending on the PCL and DHCA composition by differential scanning calorimetry （DSC） measurements. Wide angle X-ray dif- fraction （WXRD） analysis showed semi-crystalline of the PCL and PCL-co-PDHCA polymers. The PCL-co-PDHCA copolymers showed good photoreactivities and fluorescent properties. Crosslinking of the cin- namoyl groups in the copolymers caused by UV irradiation affected the thermal stability and wettability slightly. Moreover, the hydrolysis experiments revealed that copolyrners are facile degradable.
