Study On Synthesis Of A New Type Of Amphiphilic Miktoarm Star-shaped Copolymers

The relationship between the structure and properties of copolymers areattentioned by many groups (e.g, their self-assembling behavior in solution and themorphologies of microdomain), and the synthesis of copolymers with well-definedstructure is a primary work. As the development of controlling/"living"polymerization techniques, which provided the reliable experiment basis for synthesisof a series of copolymers with complicated structure (such as the cyclic, comb, starand multiblock copolymers). However, it is difficult to use a single polymerizationmechanism to synthesize these copolymers, and the monomers suited for a singlepolymerization is also limited. Thus, it is an important strategy to combine themultiple polymerization mechanism to synthesize these copolymers with complicatedstructure. Using this method, the monomers available for designing are expanded andthe merits of different polymerization mechanism are combined together.In this thesis, the synthesis and characterization of amphiphilic ABC 3-Miktoarmand ABCD 4-Miktoarm star-shaped copolymers are described by combining the"Living" Anionic Polymerization, ATRP with ROP mechanism, and thetransformation of functional groups on (co)polymer and the coupling reaction("Click" Reaction) are also used. Our work provided an universal method for thesynthesis of copolymers with complicated structure. The essential results obtained areshowed as follows:1. The amphiphilic well-defined ABC 3-Miktoarm copolymers of star(PS-PEO-PCL), star(PS-PEO-PEEGE) and star(PS-PEO-PG) were designed and synthesized. Firstly, the poly(styryl)lithium(PS^-Li⁺) was capped by EEGE to form thefunctionalized polystyrene(PS-EEGE) with an activeω-hydroxyl group and anω'-ethoxyethyl-protected hydroxyl group, then the diblock copolymer of PS-b-PEOwith an ethoxyethyl-protected hydroxyl group at the junction point was obtained byROP of EO using PS-EEGE as macroinitiator in the presence of diphenylmethylpotassium(DPMK) and following the termination of living PEO species withbromoethane. Afterwards, the ethoxyethyl-protected hydroxyl group at the junctionpoint of PS-b-PEO copolymer was acidolyzed and saponified in formic-acid andKOH solution system successively, and the PS-b-PEO copolymer with an activehydroxyl group at the junction point was recovered. Finally, this diblock copolymer ofPS-b-PEO served as macro-initiator in the presence of tin(â…¡)-bis(2-ethylhexanoate)(Sn(Oct)₂) for ROP of e-CL and the star (PS-PEO-PCL) terpolymers were obtained.The PS-b-PEO copolymer was also served as macroinitiator in the presence ofDPMK for ROP of EEGE to give the star (PS-PEO-PEEGE), and the star(PS-PEO-PG) terpolymer was obtained by the acidolysis and saponification of star(PS-PEO-PEEGE).All the intermediates and target products were characterized by ¹H NMR,SEC,FT-IR and MALDI-TOF MS in detail.2. The amphiphilic well-defined ABCD 4-Miktoarm copolymers of star(PS-PtBA-PI-PEO) was designed and synthesized. Using the functionalized PS-EEGE asthe base polymer, the propargyl group and bromide atom were introdulced onto PSend by a series of modification of the functional group. The obtained polymer wasused as the macroinitiator and the diblock copolymer of PS-b-PtBA with a propargylgroup at the junction point was obtained by the ATRP of tBA. The functionalizedPI-EEGE was also prepared by the capping reaction of poly(isoprene)lithium(PI^-Li⁺)with EEGE, which had an "active" hydroxyl group and anω'-ethoxyethyl-protectedhydroxyl group. The diblock copolymer of PI-b-PEO with a protected hydroxyl groupat the junction point was synthezised by ROP of EO using PI-EEGE as macroinitiatorand DPMK as deprotonation agent. And the diblock copolymer PI-b-PEO with anazide group was obtained by a series of modification of the hydroxyl group at thejunction point. Finally, the "Click" reaction was proceeded beteewn the azide group on PI-b-PEO and the proparyl group on PS-b-PtBA in DMF using CuBr and PMDETA ascatalyst. Thus, the ABCD 4-Miktoarm star-shaped copolymer of star(PS-PEO-PI-PtBA) were obtained.The intermediates and target product were also characterized by ¹H NMR, SEC,FT-IR and MALDI-TOF MS in detail.