Block copolymers construct a variety of nanometer scale morphologies depending on the molecular parameters. So far, our group have reported that triblock copolymers consisting of amorphous end blocks and a main-chain liquid crystalline (LC) middle block showed unique characteristic in forming lamellae. In the series of reports, the LC middle block used was BB-5(3-Me), which comprised 4,4’-biphenyl dicarboxylic acid and 3-methyl-1,5-pentanediol, while the amorphous end block used was poly(ethyl methacrylate) (PEMA). Within the lamellar microdomains, the LC segments were found to extend in the direction perpendicular to the lamellar interface with folding these chain. When the molecular weight of PEMA is increased, LC segments spontaneously adjust the number of chain foldings in order to counterbalance the enlargement of amorphous interfacial area. These features result in the structural characteristic that the lamellar structures were formed at a relatively wide and asymmetric volume fraction of amorphous block (φam), 0.2 ≤ φam ≤ 0.5. On the other hand, when φam &gt; 0.5, the structure was disordered since the enlargement of amorphous segments exceed the capability of LC segments for adjusting the chain foldings, which limits the available domain spacing range. To deal with the problem above, we here demonstrate re-ordering for disordered morphology of the LC triblock copolymers with large φam (&gt; 0.5) into long-range ordered lamellar structures by adding LC homopolymers. The neat triblock copolymer with φam ~ 0.53 or ~ 0.58 forms disordered morphology, while the blends with LC homopolymers having whole φam of 0.38 shows the long-range lamellar structure according to SAXS and TEM. Such success of transition from disordered to ordered structure is dependent on the size of LC homopolymers. The present finding can lead the widening of amorphous volume fraction range for forming lamellar structures, which is beneficial to create useful nano-materials.

Re-ordering for disordered structure of an amorphous – b – main-chain liquid crystal – b – amorphous copolymer into ordered lamellar structure by adding homo liquid crystalline chains

256th National Meeting (2018)

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