Preparation And Characterization Of Environmental Responsive Polymeric-materials By Thiol-ene Click Chemistry

Environmental responsive materials, as known as smart materials, are a new type of functional polymeric materials, which are rapidly developed in recent years. Such functional materials can fast respond to the external stimuli, resulting in the dramatic changes in their structure, physical and chemical properties. So this environmental responsive material is also known as an environmentally sensitive, intelligent or stimuli-responsive material. As a rapid response to specific external stimuli, environmental responsive materials are widely used in drug controlled release, adsorbents, sensors and other biological tissues.Based on a large number of literature investigation, two kinds of environmentally responsive polymeric materials were prepared in this thesis via ring opening polymerization and click chemistry methods. The responsive performances of these materials were studied.(1) As a reduction-responsive monomer, monomer Ml with a disulfide bond in the internal molecular and two double bonds at the both sides was successfully synthesized from cystamine dihydrochloride and allyl chlorocarbonate via molecular design. After the esterification reaction of polyethylene glycol (PEG) and cysteamine under the catalysis of p-toluenesulfonic acid, the terminal with thiol polymer mPEG-SH (P1B) was obtained, resulting in the modification of hydrophilic segment of polyethylene glycol (PEG). By changing the ratios of monomer Ml and M2, reduction-responsive hydrophobic polymer P1A was synthesized under the irradiation of UV light (365 nm) for 2 hours, in which DMPA as a photosensitizer catalyst. The reducing response amphiphilic triblock copolymer mPEG-b-P1-b-mPEG was prepared from P1A and P1B via the same method. Dynamic light scattering (DLS), transmission electron microscopy (TEM) and fluorescence spectroscopy were used to study the self-assembly, stability and reduction-responsive released behaviors of the amphiphilic micelles.(2) Monomer M3 with double bond was synthesized from D L-homocysteine thiolactone hydrochloride and acryloyl chloride. As a thiol reagent, the monomer M3 can be reacted with primary amine via ring-opening reaction. Therefore, after N, N-diethyl ethylenediamine and N, N-diisopropylethylamine ethylenediamine reacted with the monomer M3, the thiol would react with the double bond on the side chain via thiol-olefin click addition reaction, resulting in pH responsive polymers P2 and polymer P3. In this way, the monomer was synthesized by one-step method and then the pH responsive polymer was synthesized by one-step method. The method was simple, rapid and mild. The molecular weight and molecular weight distribution of the polymer, as well as the pH response of the polymer were studied by GPC, UV-VIS spectrophotometer.