Star terpolymer

By using a combination of RAFT and ring opening polymerization (ROP), (polyethylene oxide) methyl ether)(polystyrene)(poly(L-lactide) 3-miktoarm star terpolymers have been successfully synthesized [182]. The synthetic approach involved the reaction of the cw-functionalized - OH group of the poly(ethylene oxide) methyl ether with maleic anhydride under conditions where only one hydroxyl group can be esterified (MPEO). The double bond... 

By utilizing a combination of RAFT and cationic ROP, the synthesis of [poly(methyl methacrylate)][poly(l,3-dioxepane)][polystyrene] miktoarm star terpolymers was achieved [182], The approach involved the synthesis of PS functionalized with a dithiobenzoate group by RAFT polymerization and subsequent reaction with hydroxyethylene cinnamate (Scheme 98). The newly created hydroxyl group was then used for the cationic ring opening polymerization of 1,3-dioxepane (DOP). The remaining dithiobenzoate group was used for the RAFT polymerization of methyl methacrylate. 

Blending of ABC Miktoarm-Star Terpolymers with AB-Diblock Copolymers... 

Besides linear-block copolymers, also blends with miktoarm-star terpolymers have been reported [193]. Blending a PS-arm-PB-arm-P2VP miktoarm-star terpolymer showing hexagonal symmetry with a PS- -P2VP diblock... 

Li, Z. B. Hillmyer, M. A. Lodge, T. P., Control of structure in multicompartment micelles by blending mu-ABC star terpolymers with AB diblock copolymers. Macromolecules 2006, 39, 765-771. 

Miktoarm star terpolymers of the type ABC have been prepared by several methods. Iatrou and Hadjichristidis reported the synthesis of a miktoarm star consisting of PS, PI and PB branches radiating from the star center [51]. This was achieved using the chlorosilane method and the step by step linking of the different branches to the trichloromethylsilane, which was the linking agent, as shown in Scheme 19. 

The morphological investigation of a three miktoarm star terpolymer was first reported by Hadjichristidis et al. [81]. A SIB miktoarm star with MWs of the arms PS 20.7 K/PI 15.6 K/PBd 12.2 K and a volume fraction of PS equal to 0.4 formed PS cylinders in a polydiene matrix. Due to the low molecular weights the polydiene arms formed one phase. The cylinders are in contrast to the lamellae expected for diblock copolymers but the behavior is analogous to the behavior of I2S and S2I miktoarm stars of the same composition. 

Fig. 8 Multicompartment micelle formation from p-EOF star terpolymers and binary blends of p-EOF/EO. (a) Hamburger micelle from p-EOF with a very long PEO block, (b) Segmented wormlike micelle from p-EOF with a short PEO block, (c) Hamburger micelle from blends of p-EOF/EO. Reprinted with permission from Hillmyer et al. [79]. Copyright 2006 American...

Yamauchi K, Takahashi K (2003) Microdomain morphology in an ABC 3-miktoarm star terpolymer a study by energy-filtering TEM and 3D electron tomography. Macromolecules 36 6962-6966... 

A (PI)(PS)(PDMS) miktoarm star terpolymer was synthesized by the same method.97 The (PI)(PS)Si-(CH3)C1 macromolecular linking agent was prepared as previously mentioned, followed by the addition of the living PDMSLi chains to give the desired product. Also in this case a well-defined polymer with narrow molecular weight distribution was obtained. 

Dumas et al.124 125 have developed a procedure for the synthesis of ABC miktoarm star terpolymers containing amphiphilic branches. Styrene was polymerized in THF at —78 °C using cumylpotassium as initiator. The living chains were then reacted with 1 - [4- (2 - tcrt- b i ityld imethylsiloxy) ethyl] phenyl-1 -phen-ylethylene, as illustrated in Scheme 52. The living center was then used to initiate the polymerization... 

The alcoholate was alternatively reacted with tin octoate to initiate the polymerization of L-lactide (LL) and produce (PS)(PEO)(PLL) star terpolymer. In another application of the method, the 1,1-diphenyl -alkylpotassium intermediate (I) was used to initiate the polymerization of MM A at —78 °C. After de-protecting and activating the hydroxyl group, the polymerization of ethylene oxide was initiated, leading to the formation of the (PS)(PMMA)(PEO) star terpolymer. If e-CL is polymerized instead of EO, then (PS)(PMMA)(Pe-CL) stars are produced. Limited characterization data were given for these stars. In all cases two of the arms grow from the star center and thus cannot be isolated and characterized. However, interesting amphiphilic structures were obtained. 

Star terpolymers of the ABC2, ABC4 and AB2C2 were synthesized, where A, B and C are PS, PI and poly(Q -methylstyrene)(PaMeS), respectively. As an example, the reactions used for the synthesis of one of the most complex star architectures, (PS)(PI)2(P(zMeS)2, are given in Scheme 96. 

Using the chlorosilane approach, Iatrou and Hadjichristidis synthesized 3-miktoarm star terpolymers of the ABC type [232] and 4-miktoarm star copolymers and quaterpolymers of the A2B2 and ABCD type [233], respectively. The synthesis of the ABC star was based on the following reactions (Scheme 76). 

Very recently, Hadjichristidis and co-workers [240] synthesized model 3-mik-toarm star terpolymers of styrene, isoprene, and methyl methacrylate. This... 

In fact,Stadler and co-workers [252] recently synthesized an ABC 3-miktoarm star terpolymer having arms of PS, PI, and PMMA using the approach shown in Scheme 84. After purification this polymer exhibited 1= 1.13 as measured by SEC. Unfortunately no absolute characterization was performed. 

Li Z, Hillmyer MA, Lodge TP (2006) Morphologies of multicompaitment micelles formed by ABC miktotirm star terpolymers. Langmuir 22 9409-9417... 

Junnila S, Houhenov N, Hanski S, latrou H, Hirao A, Hadjichristidis N, Ikkala O (2010) Hierarchical smectic self-assembly of an ABC miktoarm star terpolymer with a helical polypeptide arm. Macromolecules 43 9071-9076... 

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