Synthesis and Association Behavior of Telechelic Poly(N-isopropylacrylamides) with Azobenzene End Groups
摘要:
A telechelic poly(N-isopropylacrylamide) (PNIPAM) with azobenzene end-groups (telechelic Az-PNIPAM) was prepared by reversible addition-fragmentation chain transfer (RAFT) free radical polymerization of NIPAM. This polymer self-assembles in cold water forming nanoparticles with a hydrodynamic radius (RH) of 8nm and an aggregation number of 29 chains. The thermoresponsive behavior of Az-PNIPAM in water was investigated by turbidimetry and light scattering. In addition, the photoresponsive behavior of aqueous Az-PNIPAM was investigated by monitoring the changes with temperature of the solution and transmittance at 650nm before and after irradiation at 366nm.
Synthesis and Association Behavior of Telechelic Poly(N-isopropylacrylamides) with Azobenzene End Groups
摘要:
A telechelic poly(N-isopropylacrylamide) (PNIPAM) with azobenzene end-groups (telechelic Az-PNIPAM) was prepared by reversible addition-fragmentation chain transfer (RAFT) free radical polymerization of NIPAM. This polymer self-assembles in cold water forming nanoparticles with a hydrodynamic radius (RH) of 8nm and an aggregation number of 29 chains. The thermoresponsive behavior of Az-PNIPAM in water was investigated by turbidimetry and light scattering. In addition, the photoresponsive behavior of aqueous Az-PNIPAM was investigated by monitoring the changes with temperature of the solution and transmittance at 650nm before and after irradiation at 366nm.
Method and apparatus for providing optical anisotropy to polymeric film and optical anisotropic medium
申请人:Fuji Xerox Co., Ltd.
公开号:US06512085B1
公开(公告)日:2003-01-28
A method of providing a polymeric film with optical anisotropy by applying a polarized light to a polymeric film is disclosed. In the method, a photoisomerizable group or a photoisomerizable molecule has a T (thermal) type photochromic property capable of being isomerized by a thermal back reaction after the isomerization by light. The method includes two successive steps, that is, a step of applying a polarized light to the polymeric film and a step of shutting off a polarized light and leaving the film as it is, and controls the temperature of the polymeric film for enhancing the orientation of the photoisomerizable group or the photoisomerizable molecule induced by the thermal back reaction. An apparatus for practicing the method and an optical anisotropic medium having the polymeric film with high optical anisotropy obtained by the method are also provided.
The liquid-crystalline diols with mesogenic groups of different structures were synthetized and their temperature behavior and existence of mesophases were determined. These compounds were also reacted with phenylisocyanate to form bis-urethanes at the ratio of reactive groups [OH]/[NCO] = 1/1. The changes of phase transition temperatures due to the change of H-O-H to H-N-H interactions have been investigated. Generally, the introduction of a phenylurethane group into the molecule suppresses the occurence of mesophases; in the case of simple mesogens the mesophases disappear completely. Stiff substituents bound to mesogen as end groups (such as the phenyl group, alkoxy group, etc.) stabilize the mesophases to such a degree that the negative influence of urethane group is compensated and the LC properties are recovered.
Synthesis and Association Behavior of Telechelic Poly(<i>N</i>-isopropylacrylamides) with Azobenzene End Groups
作者:Norihito Ishii、Rodolphe Obeid、Xing-Ping Qiu、Jun-ichi Mamiya、Tomiki Ikeda、Françoise M. Winnik
DOI:10.1080/15421406.2010.495899
日期:2010.10.8
A telechelic poly(N-isopropylacrylamide) (PNIPAM) with azobenzene end-groups (telechelic Az-PNIPAM) was prepared by reversible addition-fragmentation chain transfer (RAFT) free radical polymerization of NIPAM. This polymer self-assembles in cold water forming nanoparticles with a hydrodynamic radius (RH) of 8nm and an aggregation number of 29 chains. The thermoresponsive behavior of Az-PNIPAM in water was investigated by turbidimetry and light scattering. In addition, the photoresponsive behavior of aqueous Az-PNIPAM was investigated by monitoring the changes with temperature of the solution and transmittance at 650nm before and after irradiation at 366nm.