The Effect of Molecular Architecture on the Thermotropic Behavior of Poly[11-(4‘-cyanophenyl-4‘‘-phenoxy)undecyl acrylate] and Its Relation to Polydispersity

Abstract

Contrary to theoretical predictions on rodlike molecules (mixture of axial ratios) and previous experimental speculations on side chain liquid crystalline polymers (mixture of molecular weights), the breadth of the isotropization transition of poly[11-(4‘-cyanophenyl-4‘‘-phenoxy)undecyl acrylate] is not broadened by polydispersity in chain length alone. Instead, it is broadened by the limited miscibility of a mixture of branched structures. SCLCPs and their mesogenic side chains can therefore be treated as mixtures of random coils and monodisperse rods. This was demonstrated by comparing the thermotropic behavior of linear and three-arm star poly[11-(4‘-cyanophenyl-4‘‘-phenoxy)undecyl acrylate]s prepared by atom-transfer radical polymerization (ATRP), and their binary blends and unmixed composites. The biphasic region of linear polymers with pdi = 1.15−1.49, and of their binary mixtures, is extremely narrow. Although 3-arm star polymers with pdi = 1.11−2.20 also exhibit extremely narrow isotropization transitions, binary mixtures of the star polymers with significant differences in branching density have limited miscibility and broad isotropization transitions. The broad isotropization transition of unfractionated poly[11-(4‘-cyanophenyl-4‘‘-phenoxy)undecyl acrylate] prepared by standard radical polymerization indicates that it also contains a mixture of branched structures due to chain transfer to polymer at high monomer conversion. 11-(4‘-Cyanophenyl-4‘‘-phenoxy)undecyl acrylate is the most highly functionalized monomer to be polymerized by ATRP, and the resulting 3-arm star polymers are the first star polymers synthesized by ATRP.

Mesogen-jacketed liquid crystalline polymers via stable free radical polymerization

“…High molecular weights and conversions can be reached during the first hours of reaction without any additives and at lower temperature than required for simple styrene polymerization. These high rates of polymerization occur at temperatures at least 15 8 C lower than usually reported for PS (see Fig. 7 and 8).…”

Jacketed polymers: Controlled synthesis of mesogen‐jacketed polymers and block copolymers

“…[38][39][40][41] Well-defined star MJLCPs remained a challenge until the controlled radical polymerization of MJLCPs was discovered. There are two different methodologies, arm-first and core-first methods.…”

Synthesis and Characterization of Lactone Functional Macromonomers by End Group Deactivation and Their Use in Miktoarm Star Polymer

“…The binding of the arms is achieved by using either a difunctional monomer or a multifunctional terminating agent. The core-first method is based on a multifunctional core used as initiator to initiate the polymerization of monomer to form a multiarm star-shaped polymer [10]. Between the two methods, the core-first approach with multifunctional initiator has received greater attention, since it is easy to control the structure of a star polymer.…”