Synthesis of liquid crystalline–amorphous block copolymers by combination of CFRP and ATRP mechanisms

Abstract

Block copolymers of liquid crystalline 6-(4-cyanobiphenyl-4Ј-oxy) hexyl acrylate (LC6) and styrene (St) were obtained by the combination of two different freeradical polymerization mechanisms namely conventional free-radical polymerization (CFRP) and atom transfer radical polymerization (ATRP). In the first part, thermosensitive azo alkyl halide, difunctional initiator (AI), was prepared and then used for CFRP of LC6 monomer. The obtained bromine-ended difunctional liquid crystalline polymers (PLC6) were used as initiators in ATRP of St, in bulk in conjunction with CuBr/N,N,NЈ,NЉ,NЉ-pentamethyldiethylenetriamine (PMDETA) as catalyst. In the second part, AI was firstly polymerized by CFRP in the presence of St and then the obtained difunctional bromine ended polystyrenes (PSt) were used as initiators in ATRP of LC6 in diphenyl ether solvent in conjuction with CuBr/PMDETA. The spectral, thermal, and optical measurements confirmed a fully controlled living polymerization, which results in formation of ABA-type block copolymers with very narrow polydispersities. In both cases, blocks of the different chemical composition were segregated in the solid and melt phases. The mesophase transition temperatures of the liquid crystalline block were found to be very similar to those of the corresponding homopolymers.

Synthesis of acetophenone formaldehyde resin containing ABA type block copolymers by ATRP

“…Among them, ATRP has been successfully applied to the synthesis of well‐defined macromolecular architectures such as comb, star, branched, and dendritic macromolecules 21–28, 45. ATRP has been shown to be a versatile technique for the controlled polymerization of many monomer classes, including (meth)acrylates, (meth)acrylamides, (substituted) styrenes, and miscellaneous monomers 29–39, 46–47. Moreover, this CRP technique is tolerant to a wide range of functional monomers, solvents, and initiators.…”

Synthesis and characterization of a novel liquid crystalline star‐shaped polymer based on α‐CD core via ATRP

“…In recent years, liquid crystal homopolymers and block copolymers have been widely studied because of their potential applications such as switchable windows, displays, color projectors, and other electric-optical systems. [24][25][26][27][28] The azobenzene-containing sidechain liquid crystal polymers are distinguished for their properties as materials in a range of advanced electro-optical technologies, 29 because it is well known that azobenzene chromophores exhibit photoinduced reversible trans-cis isomerization, which can significantly influence the bulk and solvent properties of azobenzene-containing side-chain liquid crystal polymer. 30 The interests of the scientists are not only on the performance of the linear liquid-crystal polymer, but also on the behavior of the star-shaped polymer.…”

Graft copolymerization of methyl methacrylate with an N‐substituted maleimide–liquid‐crystalline copolymer by atom transfer radical polymerization

“…The synthesis of copolymers containing amorphous and liquid-crystalline (LC) segments are also popular and can originate a vast number of possible combinations of properties and structures. [24][25][26][27][28][29][30][31][32][33][34] The molecular design and synthesis of LC polymers, especially LC block or graft copolymers, toward well-defined polymer nanoarchitectures have captured considerable attention. Copolymers with both LC properties and phase-separation properties offer unique opportunities to manipulate LC order in nanometer scales.…”

“…The synthesis of copolymers containing amorphous and liquid‐crystalline (LC) segments are also popular and can originate a vast number of possible combinations of properties and structures 24–34. The molecular design and synthesis of LC polymers, especially LC block or graft copolymers, toward well‐defined polymer nanoarchitectures have captured considerable attention.…”