One-Pot Synthesis Of Amphiphilic Graft And Multiblock Copolymers

The design and synthesis of copolymers with complex architectures are always pursued by polymer chemists. In the past decade, there is tremendous development in controlled polymerization technique. It is the most useful method in polymer synthesis chemistry by combination of the multiple polymerization mechanism and highly efficient coupling methods. One-pot strategy has gained increasing attention in the synthesis of different polymer architectures, because it can reduce the steps of reaction and purification. By means of these methods, a variety of linear and nonlinear (such as comb-shaped, star-shaped, dendritic, cyclic) copolymers are tailored and synthesized. They may show quite different microdomain morphologies in bulk and self-assembly behavior in solution, which have great potential applications in chemistry, materials, physics and biology.In this thesis, a series of copolymers with complex structures (amphiphilic graft copolymers and triblock copolymers) were synthesized via one-pot strategy by combination of highly efficient coupling reactions ("click" chemistry, ATNRC reaction and SET-NRC reaction) with controlled/"living" polymerization (SET-LRP, anionic polymerization, ROP and ATRP). All the intermediates and target products were characterized by different means such as SEC,1H NMR and FT-IR etc in detail. The main work done in this thesis shows as follows:1. A new strategy for one-pot preparation of ABA-type block-graft copolymers via a combination of atom transfer nitroxide radical coupling (ATNRC) reaction with "click" chemistry was completed. Firstly, sequential ring-opening polymerization (ROP) of 4-glycidyloxy-2,2,6,6-tetramethyl piperidine-1-oxyl (GTEMPO) and ethoxyethyl glycidyl ether (EEGE) was proceeded for backbone with pended TEMPO and ethoxyethyl-protected hydroxyl groups, which were recovered by hydrolysis and esterified with 2-bromoisobutyryl bromide and subsequently converted into azide groups by NaN3. Then, bromine-containing poly(tert-butyl acrylate) (PtBA-Br) was synthesized by atom transfer radical polymerization (ATRP). Alkyne-containing polystyrene (PS-alkyne) was prepared by capping polystyryl-lithium with ethylene oxide (EO) and subsequent modification by propargyl bromide. Finally, one-pot reaction of "click" chemistry and ATNRC reaction was proceeded simultaneously between backbone and side chains(PtBA-Br, PS-alkyne), and the amphiphilic ABA-type block-graft copolymer with PEO as main chain, PS and PtBA as side chains was obtained. The effects of catalyst systems on the one-pot reaction were discussed.2. Triblock copolymers of polystyrene-block-poly(ethylene oxide)-block-poly (tert-butyl acrylate) (PS-6-PEO-b-PtBA) were prepared via combination of single electron transfer living radical polymerization (SET-LRP) with "click" chemistry using Cu(0)/N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA) as catalyst system. The?,?-hetero-functionalized PEO with an ethoxyethyl-protected hydroxyl group and an active hydroxyl group was synthesized via anionic ring-opening polymerization (ROP) of ethylene oxide (EO) using potassium 2-(1-ethoxyethoxy) ethoxide as initiator. After further modifications of the end groups, the PEO with alkyne and bromine groups was obtained. Meanwhile, bromine-terminated polystyrene (PS-Br) was synthesized by atom transfer radical polymerization (ATRP), then the bromine end groups were transformed to azide groups by nucleophilic substitution reaction in N, N-dimethylformamide (DMF) in the presence of excessive sodium azide. Lastly, in the presence of Cu(0)/PMDETA, bromine end group of PEO initiated the polymerization of tert-butyl acrylate (tBA) by SET-LRP, the formed Cu(?) in situ was used directly to catalyze the "click" coupling between azide group of PS and alkyne group of PEO. Thus the triblock copolymers PS-b-PEO-b-PtBA could be prepared by one-pot strategy. 3. Cu(0) catalyzed one-pot strategy by combination of single electron transfer-nitroxide radical coupling (SET-NRC) reaction with "click" chemistry was carried out in the synthesis of ABC triblock copolymers. Firstly, the precursors?,?-heterofunctionalized poly(ethylene oxide) (PEO) with a 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) group and an alkyne group, polystyrene (PS) and poly(tert-butyl acrylate) (PtBA) with bromine or azide end group, were designed and synthesized respectively. Then the one-pot coupling reactions between these precursors were carried out:The SET-NRC reaction between bromine group and nitroxide radical group, subsequently "click" coupling between azide and alkyne group. It was noticeable that Cu(?) generated from Cu(0) by SET mechanism was utilized to catalyze "click" chemistry in situ. In order to estimate the effect of Cu(0) on the one-pot reaction, a comparative analysis was performed in presence of different Cu(0) species(nanosized Cu(0), reduction Cu(0)). The result showed that reduction Cu(0) with more active surface area could accelerate the one-pot reaction of SET-NRC and "click" chemistry significantly.