Miktoarm 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... 

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. 

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... 

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). 

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. 

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... 

Multiresponsive double hydrophilic (PEO) (PDMAEMA) (PNIPAAM) miktoarm star terpolymers were prepared by ATRP and click reactions. The terpolymers were molecularly dissolved at room temperature in aqueous solutions at pH below 7. Upon increasing the pH spherical and near-monodisperse micelles having PDMAEMA, cores were formed. On the other hand, starting from molecularly dissolved terpolymers at pH 4, micelles could be obtained by... 

Figure 21 Schematic illustrations for pH- and thermo-induced supramolecular self-assembly of (PEO)(PDEAEMA)(PNIPAM) ABC miktoarm star terpolymers into two types of micellar aggregates possessing hybrid coronas in aqueous solution. Reprinted from Zhang, Y. Liu, H. Hu, J. et at.

Theoretical approximations and morphology predictions were recently carried out for miktoarm star terpolymers of the ABC type. The literature concerning theoretical predictions for this complex architeaure is rather limited, as the synthesis of such materials leading to morphologically three-phase stmaures has been developed rather recently. The behavior of miktoarm star terpolymers was simulated using the Monte Carlo calculation method. This approach was already used for the microdomain structural behavior of diblock copolymers of the AB type, and the consideration that needed to be taken into account for the calculations was the addition of the C chain at the common junction point of the A... 

Microdomain stmctures of 3-miktoarm star terpolymers in a three-dimensional space were investigated using the dynamic density functional theory (DDFT). Analysis of DDFT demonstrates that the junction points are restricted to lie on... 

The first morphological characterization of a miktoarm star terpolymer was reported on a sample consisting of PS, PI, and... 

The miktoarm star terpolymers (PS)(PI)(P2VP) were studied morphologically as well. It was observed that this material exhibited similarities with the SIM terpolymers, and the junaion points were again confined to lines instead of interfaces. 

The assembly of ABC miktoarm stars can yield nanostmc-tures with complex multicompartment cores and also interesting properties. The potential for the assembly of ABC miktoarm star terpolymers to yield complex nanostmctures with interesting morphologies has both been demonstrated through simulation and experimental studies. 

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