Tuning the Thermal Properties of Azopolymers Synthesized by Post‐Functionalization of Poly(propargyl Methacrylate) with Azobenzene Azides: Influence on the Generation of Linear and Circular Birefringences

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/macp.201800318. AzopolymersA series of side-chain polymers with a bifunctional repeating unit are prepared by post-polymerization functionalization of poly(propargyl methacrylate) (PPMA) with several azides derived from bis(hydroxymethyl) propionic acid (bis-MPA). The azide incorporates one photoresponsive 4-cyanoazobenzene unit and one photoinert promesogenic moiety at each repeating unit. Both the effect of the photoinert (4-cyanobipheynyl vs 4-cyanotolane) and of the linking group (ester vs carbamate) on the liquid crystalline properties and the generation of optical anisotropy, linear or circular birefringences are explored.

Strategies to Stabilize the Photoinduced Supramolecular Chirality in Azobenzene Liquid Crystalline Polymers

“…Functionalized homopolymers were afforded by the postpolymerization modification of poly(propargyl methacrylate) with the described azides by CuAAC, whose viability and versatility has been previously recognized (Figure 2) [24,25,26]. Block copolymers were approached using a recently devised strategy based on the sequential ATRP polymerization of trimethylsilylpropargyl methacrylate and methyl methacrylate, and subsequent removal of the trimethylsilyl protecting groups [27].…”

“…Details of the synthesis and characterization of the azides are given in the supplementary information. The preparation of poly(propagyl methacrylate)s P 70 and P 100 and their characterization have been described elsewhere [25,26]. Postpolymerization functionalization of the polymers with the azides by CuAAC was accomplished using previously reported conditions [24].…”

“…We have studied this phenomenon on a series of azobenzene polymethacrylate homopolymers and related block copolymers. The polymers were prepared by combining the atom transfer radical polymerization (ATRP) of poly(propargyl methacrylate) with postfunctionalization by copper(I) catalyzed alkyne-azide cycloaddition (CuAAC) using azobenzene azides [24,25,26,27]. With this advantageous combination, it was possible to efficiently change the nature of the functional moieties.…”

Polymeric Self-Assemblies Based on tetra-ortho-Substituted Azobenzene as Visible Light Responsive Nanocarriers

“…Functionalization of the polycarbonate block with azides N 3 -Azo or N 3 -AzoOMe, via CuAAC was approached using CuBr/PMDETA in DMF ( Figure 1) [22]. Progress of the functionalization was evaluated by 1 H-NMR from the disappearance of the signal at δ = 2.48 ppm, corresponding this signal to the proton in the propargyl side-group, and by the appearance of a new signal at 7.65 ppm from the proton in the triazole ring (Supplementary Materials, Figures S1 and S2).…”

“…Likewise, these linear-linear BCs have been designed consisting of PEG as the hydrophilic segment bind to a hydrophobic aliphatic polycarbonate based on the bis-MPA building block. The presence of two hydroxyl and one carboxylic groups makes bis-MPA a remarkably versatile basic unit from which diverse polymeric architectures have been prepared ranging from dendrons and dendrimers to linear polymers either with bis-MPA based pending units or forming the polymer main chain [21,22]. Additionally, it is usually anticipated that the presence of ester or carbonate bonds hydrolysable bonds on the resulting polymers potentially confers biodegradability, which makes them valuable candidates for biomedical applications [23][24][25].…”