Preparation And Properties Of Tetradecaborate And Four - Arm Pentaerythritol Star Polymer

In recent years, the star polymer with its unique structure and properties has attracted widespread attention, the design and the synthesis and structure-property relationships of star polymers have become one of the forefront topics in the field of polymer chemistry. We mainly modify β-cyclodextrin and pentaerythritol to the atom transfer radical polymerization (ATRP) initiator, then the star polymer was synthesized by ATRP. So star polymer has precise structure. ATRP method has the advantages of free radical polymerization and living polymerization, such as:wide range of suitable monomers and good controllability, and a variety of different structures of novel polymer. Then we synthesized a series of star polymers by host-guest chemistry, click reaction and other methods, the paper work from the following five different areas:First, we designed and synthesized Janus type star polymer N3-CD-(PAA)14 based on cyclodextrin, first the β-CD-(N3)7 is synthesized by iodinated cyclodextrin, then utilize the reaction of dibromo isobutyryl bromide and β?-CD-(N3)7 synthesis ATRP initiator, followed by using t-butyl acrylate as ATRP monomers, synthesized Janus type star polymer (N3)7-β-CD-(PtBA)14, finally Janus type star polymer (N3)7-β-CD-(PAA)14 isobtained by hydrolysis. Duo to PAA chain is a pH-sensitive polymer, as the pH is higher than 5, the PAA chain expansion, however, when the pH is lower than 5, the PAA chain shrink. However, β-cyclodextrin is dissolved in water, so when the pH is less than 5 is amphiphilic star polymer. We studied their self-assembly behavior at different pH solvents. We analyze their micellar behavior in different pH solutions by transmission electron microscopy, fluorescence spectrophotometer, and dynamic light scattering.Second, we designed and synthesized Janus type star polymer RhB-CD-(PDMAEMA)14 based on cyclodextrin, first the β-CD-(N3)7 is synthesized by iodinated cyclodextrin, then utilize the reaction of dibromo isobutyryl bromide and β-CD-(N3)7 synthesis ATRP initiator, Followed by using DMAEMA as ATRP monomers, synthesized Janus type star polymer (N3)7-β-CD-(PDMAEMA)14. RhB-β-CD-(PDMAEMA)14 is obtained by click reaction. Due to PDMAEMA thermo-sensitive polymer. At low temperature, the PDMAEMA chain expansion, however, at high temperature, the PAA chain shrink. In the meantime, we detect the Janus type star polymer RhB-CD- (PDMAEMA)14 fluorescence intensity at varying temperature.we found that the fluorescence intensity of the RhB-CD-(PDMAEMA)14 is becoming low with the increase of temperature, and fluorescence intensity at 582 nm exhibits a linear decrease with increasing temperature.Third, we designed and synthesizeed two star polymer (Fc)4-PER-(PDMAEMA)4 and (CD)4-PER-(PDMAEMA)4 with four arms. Then the hydrogel was synthesized by host-guest interaction between Fc and CD to get mesh structure. First reacted between pentaerythritol and dibromo isobutyryl bromide to obtain ATRP initiator. Followed by using DMAEMA as ATRP monomers, Synthesied four arms star polymer PER-(PDMAEMA)4, Sodium azide then modified bromine to generate azide.Then azide reacted with 2-Propynyl-l-ferrocenoate and Propynyl-β-cyclodextrin through click reaction respectively. At last, star polymer (Fc)4-PER-(PDMAEMA)4 and (CD)4-PER-(PDMAEMA)4 through host-guest interaction obtained hydrogel.Fourth, we designed and synthesized two star polymer (Fc)4-PER-(PAA)4 and (CD)4-PER-(PAA)4 with four arms.The hydrogel was synthesized by host-guest interaction between Fc and CD to get mesh structure. First reaction between pentaerythritol and dibromo isobutyryl bromide obtained ATRP initiator. Followed by using t-Ba as ATRP monomers, four arms star polymer PER-(PtBA)4 was obtained. Sodium azide then modified bromine to generate azide.Then azide reacted with 2-Propynyl-1-ferrocenoate and Propynyl-β-cyclodextrin through click reaction respectively. (Fc)4-PER-(PAA)4 and (CD)4-PER-(PAA)4 was obtained by hydrolysis. At last, star polymer (Fc)4-PER-(PAA)4 and (CD)4-PER-(PAA)4 used host-guest interaction to get hydrogel.Fifth, we used (N3)7-β-CD-(PAA)14 for immobilized enzyme, due to there was a lot of-COOH on PAA chain, which could covalent pectinase. First, we measured optimum temperature, the optimum reaction time of the immobilized enzyme activity. Then measured the immobilized enzyme activity at different pH activity, and compared with the free enzyme.We could get from the figure, we could use to determine pKa value of the molecular chain through the activity of the enzyme.