Synthesis and Characterization of Polypropyleneimine Dendrimers Having Peripheral Mesogenic Groups: Homeotropic Orientation and Mesogen Structure

Connector type‐controlled mesophase structures in poly(propyl ether imine) dendritic liquid crystals of identical dendrimer generations

“…In this context, nanophase segregation of distinct segments within the molecules having dendritic structural features hold a promise . Studies of the order and complexity, leading to distinct mesophase structures, were studied systematically using preformed dendrimers by modifying the peripheries with chosen mesogenic moieties . Elegant examples are (i) amphiphilic ionic second generation poly(amido amine) (PAMAM) dendrimer functionalized with differing amounts of myristic acid that exhibit a smectic A mesophase; (ii) second‐generation poly(propyleneimine) dendrimers peripherally functionalized with 4‐methoxybiphenyl, 4‐methoxyphenyl benzoate, trans ‐4‐(4‐pentylcyclohexyl)phenyl, 4‐fluorobiphenyl, and 3,4,5‐trifluorobiphenyl that exhibit a spontaneous homeotropic arrangement and (iii) azobenzene‐functionalized carbosilane dendrimers of first to fourth generations that prefers a smectic layer arrangement, whereas the fifth generation dendrimer of the same series prefers a rectangular columnar arrangement …”

“…Important studies in dendritic liquid crystals to understand various aspects of mesophase evolution include: (i) changes in the dendrimer types, such as, carbosilane, PAMAM, PPI, and siloxane, and a homologous series of poly(propyl ether imine) (PETIM) dendrimers and changes in the dendrimer generations; (ii) varying linker lengths connecting the dendrimer backbone and the mesogenic moiety; (iii) varying alkyl chain length at the peripheries; (iv) the mode of attachment of the mesogenic moiety to the dendrimer, such as, side on or end on; (v) changing the shape of mesogenic moieties, such as, linear, radial and banana shaped and the degree of branching in the core . In the studies of dendritic LCs, to the best of our knowledge, no work has been reported so far which deals with the study of change in the mesophase by varying the flexibility and shape of the linkers within one particular dendrimer generation.…”