Solution Behavior of Topological Isomers of Poly[11-(4‘-cyanophenyl-4‘ ‘-phenoxy)undecyl acrylate]s Prepared by Atom Transfer and Conventional Radical Polymerizations

Abstract

The solution behavior of linear, three-arm star, and comb poly[11-(4‘-cyanophenyl-4‘ ‘-phenoxy)undecyl acrylate]s previously synthesized by atom transfer radical polymerization was investigated by gel permeation chromatography (GPCPSt) and light scattering measurements in CH2Cl2, THF, and CHCl3 in order to correlate their size and shape with their molecular architecture and in order to investigate the extent of branching in the corresponding polymer prepared by conventional radical polymerization. The inaccuracy of the GPCPSt molecular weights increases as the polymers become more branched: linear < three-arm star < comb; the discrepancy between the GPCPSt and absolute molecular weights of polymers fractionated from the conventional radical polymerization is between those of the three-arm star and comb polymers in all three solvents. Light scattering studies demonstrate that CH2Cl2 is the best solvent for all of the polymers, resulting in either no aggregation or an insignificant amount of aggregation, whereas all of the topologies except the comb polymers tend to aggregate in THF and CHCl3; nevertheless, the extent of aggregation is not great enough to be detected by variations in the average GPCLS-determined molecular weights measured in any of these solvents. The tendency to aggregate in all of the solvents and the radius of gyration in CH2Cl2 decrease as the branching increases: linear > three-arm star > comb, with the polymer prepared by conventional radical polymerization being similar to the branched polymers. The scaling coefficients (R g = KM ν) of all of the polymers are similar in CH2Cl2, with ν = 0.37 for the three-arm star polymers, ν = 0.39 for the comb polymers, and ν = 0.32 for the polymer prepared by conventional radical polymerization. The relative values of the contraction factors, g = 〈R g 2〉br/〈R g 2〉lin, decrease in the order g star > g comb > g radical for the three-arm star polymers, the comb polymers, and the polymer prepared by conventional radical polymerization, respectively, in CH2Cl2.

Strategies for Tailoring LC-Functionalized Polymer: Probe Contribution of [Si–O–Si] versus [Si–C] Spacer to Thermal and Polarized Optical Performance “Driven by” Well-Designed Grafting Density and Precision in Flexible/Rigid Matrix

“…In addition, polydispersity that was mostly determined by polymerization and grafting methodology is an indispensable factor in designing SCLCPs and determining their properties. , Recently, various interactions of side chains and the functionalized density have been also confirmed . Furthermore, polymeric architectures can be designed according to topological morphology such as linear, star, cyclic, and network, major brushes/combs, etc. Because branched SCLCPs with lower viscosity compared with their linear analogues have garnered considerable attention, the significant influences of diverse topologies on remarkable physical, chemical, and biological properties have been depicted in some works. , Major previous study focused on structure–property relationship of SCLCPs based on changes of side mesogens.…”

Synthesis of Hyperbranched Polyacrylates by a Chloroinimer Approach

“…Nevertheless, as discussed in the Introduction, many of the physical properties of polymers vary with the degree of branching and can therefore be used to confirm a branched structure. One of the simplest properties to compare is the error in the GPC-determined molecular weights as a function of branching, ,, which is caused by the more compact shape of branched polymers compared to the linear polymer standards used to relate elution volume to molecular weight. Table lists the molecular weights of many of the polymers determined by both GPC relative to linear polystyrene and by 18-angle light scattering detection of the polymers eluted from the GPC by THF.…”

“…We previously synthesized the linear, , three-arm star, , comb, and six-arm star analogues of the polymers produced by SCVP of the mesogenic inimer and determined the error in the GPC PSt -determined molecular weights of the first three architectures in THF. , Figure a plots the absolute number-average molecular weights measured by GPC LS as a function of the GPC PSt -determined molecular weights in THF for four of the “hyperbranched” SCLCPs in Table . The data are plotted using the same axes as the corresponding data plotted in Figure b for the linear, three-arm star, and comb polymers reported previously.…”

“… a r = linear correlation coefficient. b Using all of the linear polymers with two different end groups reported in refs and . c Fractionated from the hyperbranched SCLCP with GPC PSt M n = 1.03 × 10 4 and PDI = 2.06 (Table ). …”

Synthesis and characterisation of star-shaped liquid crystalline polymer with a POSS core

“…Indeed, the star-shaped (three-, four-, six-arm) LC polymers with different cores have been explored extensively and their mesogenic behaviour have also been studied. [35][36][37][38][39][40] The LC polymers containing mesogenic group of phenylbenzoate moiety have got more attention due to the higher thermal stability and easier arrangement into mesophase. [35,41] Employing phenylbenzoate moiety as mesogenic group to build the star-shaped POSS LC polymer should bring about the high thermal stability and the easier formation of liquid crystal phase.…”