Synthesis, liquid crystalline mesophases and morphologies of diblock copolymers composed of a poly(dimethylsiloxane) block and a nematic liquid crystalline block

ABSTRACT

In this study, a series of liquid crystalline diblock copolymers, composed of a soft poly(dimethylsiloxane) (PDMS) block with a defined length and a side-on liquid crystalline poly(3ʹʹ-acryloyloxypropyl 2,5-di(4ʹ-butyloxybenzoyloxy) benzoate) (P3ADBB) block with different lengths, are synthesised by the atom transfer radical polymerisation. The macromolecular structures, liquid crystalline properties and the microphase-separated morphologies of the diblock copolymer are investigated by ¹H NMR, FT-IR, GPC, POM, DSC and TEM. The results show that the well-defined diblock copolymers (PDMS_n-b-P3ADBB_m) possess four different soft/rigid ratios (n = 58, m = 10, 25, 42, 66) and relatively narrow molecular distributions (PDI ≤ 1.30). P3ADBB blocks of the copolymers show nematic sub-phases, which are identical to the mesomorphic behaviour of the homopolymer P3ADBB. After being annealed at 90°C in a vacuum oven for 48 h, the copolymers form a lamellar morphology when m = 10 and morphologies of PDMS spheres embedded in P3ADBB matrix when m = 25, 42 and 66.

Graphical Abstract

KEYWORDS:

• Liquid crystalline polymer
• diblock copolymers
• atom transfer radical polymerisation
• poly(dimethylsiloxane)
• microphase separation

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental material

Supplemental data for this article can be accessed here.