Morphology of triblock copolymers

Fig. 29. Ultrathin film morphology of triblock copolymer P(S800-i>-2VP430-fi-MMA730) adsorbed from a dilute solution in chloroform onto mica as observed by contact mode SFM. The drawing on the right hand side shows the location of the blocks on the substrate. Courtesy of P. Eibeck and M. Moller...

Mogi, Y, Kotsuji, H., Kaneko, Y. et al. (1992a) Preparation and morphology of triblock copolymers of the ABC type. Macromolecules, 25,5408-5411. 

Tailoring block copolymers with three or more distinct type of blocks creates more exciting possibilities of exquisite self-assembly. The possible combination of block sequence, composition, and block molecular weight provides an enormous space for the creation of new morphologies. In multiblock copolymer with selective solvents, the dramatic expansion of parameter space poses both experimental and theoretical challenges. However, there has been very limited systematic research on the phase behavior of triblock copolymers and triblock copolymer-containing selective solvents. In the future an important aspect in the fabrication of nanomaterials by bottom-up approach would be to understand, control, and manipulate the self-assembly of phase-segregated system and to know how the selective solvent present affects the phase behavior and structure offered by amphiphilic block copolymers. 

The authors also reported on the supramolecular self-assembly from rod—coil—rod triblock copolymers prepared by copolymerization of 5-acetyl-2-aminob-ezophenone with diacetyl functionalized polystyrene with low polydispersity (Scheme 12).110 In contrast to the rod—coil diblock copolymers which exhibit multiple morphologies, the triblock copolymers were found to spontaneously form only microcapsules or spherical vesicles in solution as evidenced by optical polarized, fluorescence optical, and scanning electron microscopies (Figure 33). 

Xu, F.J., Li, J., Yuan, S.J., Zhang, Z.X, Kang, E.T., and Neoh, K.G. (2008) Thermo responsive porous membranes of controllable porous morphology from triblock copolymers of polycaprolac-tone and poly(N-isopropylacrylamide) prepared by atom transfer radical polymerization. Biomacromolecules, 9, 331. 

With increasing amoimt of triblock copolymer, blends of lamellar SBT triblock copolymers with the asymmetric SB diblock copolymer form core-shell spheres, core-shell cylinders, core-shell double gyroids, and lamellae (Fig. 34). T forms the core domains in these morphologies, which can be considered as coreshell analogues of the well-known diblock copolymer morphologies (76). 

The morphology of spin-coated films of triblock copolymers of PLLA and PDXO was investigated by AFM. These studies revealed the absence of nanoscale morphology in these films [60]. 

Linear and non-linear triblock terpolymers. Synthesis and self-assembly in selective solvents and in bulk Phase behaviour and morphologies of block copolymers... 

Chen, Z., Cui, H., Hales, K., Qi, K., Wooley, L.K. and Pochan, J.D. (2005) Unique features of triblock copolymers that aUow for the formation of unusual solution-state morphologies. ACS Polym. Prepr. (Div. Polym. Chem.), 46(1), 183. 

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