Connector type‐controlled mesophase structures in poly(propyl ether imine) dendritic liquid crystals of identical dendrimer generations. Issue 22 (27th July 2017)

• Record Type: Journal Article
• Authors: Kumar, Prabhat; Shankar Rao, D. S.; Krishna Prasad, S.; Jayaraman, Narayanaswamy
• Is Part Of: Journal of polymer science. Volume 55:Issue 22(2017)
• Page Start: 3665
• Page End: 3678
• Publication Date: 2017-07-27
• Subjects: dendrimers -- differential scanning calorimetry (DSC) -- glass transition -- liquid crystals -- X‐ray; 547
• DOI: 10.1002/pola.28709
• Languages: English
• ISSNs: 0887-624X

Abstract

ABSTRACT: Poly(propyl ether imine) (PETIM) dendrimers of one to three generations are used as dendritic cores to identify the influence of varying connector types that connect the dendritic core with peripheral mesogens on the emerging liquid crystalline (LC) properties. The LC properties vary in these dendritic liquid crystals, even when the dendrimer generations and thus the number of peripheral mesogenic moieties remain identical. PETIM dendrimer generations one to three, ester and amide connectors varying with succinates, phthalates, and succinamides, are studied herein. Cholesteryl moieties are installed at the peripheries through the above connectors to induce mesogenic properties. These modified dendritic liquid crystals reveal a layered mesophase structure in most ester and amide connector‐derivatives, whereas a third‐generation phthalate ester dendrimer favors a rectangular columnar mesophase structure. A transition from layered to a rectangular columnar structure results by a mere change in the connector varying between a succinate or succinamide or phthalate, within one particular dendrimer generation and without altering the underlying dendrimer core or the number of mesogenic moieties. The study demonstrates that in dendritic liquid crystals with essentially identical chemical constitutions, a change in the connector type connecting the mesogen with the dendrimer core is sufficient to change the mesophase structures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2017, 55, 3665–3678 Abstract : This study investigates the role of succinate, phthalate, and succinamide connector types, connecting cholesteryl moieties at the peripheries of first, second, and third generation poly(ether imine) dendrimers to afford 9 dendritic liquid crystals. Upon synthesis, studies of the liquid crystalline properties of these derivatives reveal that the mesophase structure varies between a layered structure to a rectangular columnar structure within one particular dendrimer generation, depending only on the connector type.