The Synthesis, Characterization, And Researches On The Self-assembly Behaviour And Biological Application Of New Amphiphilic Azobenzene-containing Diblock Copolymers

Azobenzene-containing polymers (azo polymers for short) have received considerable attention in recent years because of their potential applications in the fields of optical data storage, liquid crystal displays, and holographic surface relief gratings. The photoresponsive properties of azo polymers are connected with the chemical structure of backbone and types of azo chromophores. As a result, molecular design and synthesis of azo polymers with desired photoresponsive properties have aroused considerable research interest. Functional polymer microspheres with carbonyl, hydroxyl, and amino groups on their surfaces have been used to covalently bind antibodies and other proteins onto micro-spheres. The introduction of fluorescent material (such as rare earth complex) into copolymer vesicle system as a probe is a promising method and has been widely used in biological studies of liposomes and biofilms.In this article, we report the synthesis of several azo diblock copolymers PAzoM-b-PAA, p(DMAEMAm-b-AzoMn) and PNIPAM-b-PAzoM via reversible addition-fragmentation chain transfer (RAFT) polymerization. We then discussed the biological application of p(DMAEMAm-b-AzoMn) microspheres by fluorescence technique. The main contents of this paper are divided into three parts:1. An amphiphilic azobenzene diblock copolymer{2-[4-(4-methoxy phenyl azo)phenoxy]hexyl acrylate co-acrylic acid} was synthesized via reversible addition-fragmentation chain transfer polymerization in a hydrothermal reactor. The products were characterized by1H-NMR, DSC, GPC and UV-Vis spectroscopy. Different self-assembly behaviors of this amphiphilic diblock copolymer in different organic solvent with different water content were investigated. Photochromic behaviors of the amphiphilic diblock copolymer in different enviorments were investigated. A rotational mechanism was suggested for the isomerization process of PAzoM-b-PAA.2. Poly (N, N-dimethyl-ethylamine methacrylate)-block-poly{6-[4-(4-methoxy phenyl-azo) phenoxy] hexylacrylate} p(DMAEMAm-b-AzoMn) was synthesized by successive reversible addition-fragmentation chain transfer polymerization in the hydrothermal reactor. The products were characterized by hydrogen nuclear magnetic resonance, differential scanning calorimetry, gel permeation chromatography, and ultraviolet and visible absorption spectroscopy (UV-vis). In H2O/THF mixture, we found amphiphilic p(DMAEMAm-b-AzoMn) self-assembles occurred. p(DMAEMA79-b-AzoM7) self-assembled into rods, p(DMAEMA79-b-AzoM5) self-assembled into giant microspheres with rods wind around, p(DMAEMA79-b-AzoM2) self-assembled into microspheres. Photochromic behaviors of the polymers in different environments were investigated. We found the colors of diblock copolymers in films changed from yellow to orange after irradiation by ultraviolet and visible (UV) light. The rates of trans-cis photoisomerization in films were almost the same for the three p(DMAEMAm-b-AzoMn) copolymers. The rates in aqueous micellar solutions were only marginally faster than those in films for all the three diblock copolymers. The observation-of a sizable rate difference in different environments for p(DMAEMAm-b-AzoMn) suggested that a rotational mechanism might be operative for these water-soluble amphiphilic diblock copolymers. The self-assembly behaviors of three copolymers and the application of p(DMAEMA79-b-AzoM2) microspheres in biochemistry were investigated in present work.PNIPAM-b-PAzoM was synthesized by reversible addition-fragmentation chain transfer (RAFT). The self-assembly behavior of the product was discussed.3. Tb(acac)3phen (acac=acetylacetone; phen=1,10-phenanthroline) was synthesized. The complex was characterized by elemental analysis, Fourier transform infrared spectra (FTIR), and fluorescent spectra, respectively. Tb(acac)3phen-doped nanocapsules were obtained through the self-assembly of PAA-b-PAzoM diblock copolymers and the rare earth complex Tb(acac)sphen in the DMSO/H2O. The nanocapsules were characterized by TEM, fluorescence spectrometer.