Removal Of End Groups And HLB Values Of RAFT Block Polymer

So far, Reversible Addition-Fragmentation Chain Transfer Polymerization（RAFT） has become an important technique of controlled radical polymerization and has also broad application prospects in the field of releasing drug, catalysis,nano-reactor, sensors, emulsification, etc. However, RAFT chain transfer which is retained in polymer after reaction will break the regularity of the polymer structure and limit the application of the polymer. Therefore, It is great significance to remove the thiocarbonylthio end-groups.The amphiphilic polymer surfactant can be synthesized by RAFT method and the polymer emulsifiers of different Hydrophile Lipophilic Balance（HLB value） can be designed. Moreover, HLB value is an important parameter of surface activity and determines the application range of the surface activity. Therefore, how to design different HLB value of amphiphilic block copolymer and fastly and accurately determine its HLB value is the key to the research question.In this paper, the thiocarbonylthio end-groups of homopolymer or copolymer by RAFT method are cleaved through catalytic themolysis in a liquid phase. Then, HLB value is determined and the relation between HLB value of chain composition of copolymers is researched in this paper. The main research contents and results are as following:1. Homopolymer（P4VP and PS） with thiocarbonylthio end-groups is synthesized with RAFT method. The oxidation and reduction property of solvent are studied on thermolysis. The results indicate that the product of low sulphur content without crosslinking can be obtained when diethylene glycol as solvent.2. Block polymers P4VP-b-PS is synthesized by two-step process and the effect of different transition metal catalyst Cu₀（0）, Cu₀（1） and Cu₀（2） is researched in the process of catalytic thermal cleavage. The results indicate that the thiocarbonylthio end-groups can be cleaved by Cu-based catalyst. Moreover, sulfur content,crosslinking and molecular weight varies with different transition metal content.3. To determine the HLB value of P4VP-b-PS copolymer, different retentiontimes of a series of EO-PO copolymers which defined HLB values is measured by HPLC chromatography and their relationship with HLB values are established. The formulas of the HLB values of P4VP-b-PS copolymers are determined. The emulsion performance of block copolymer of different concentrations in water/n-hexane is explored.