Hierarchical self-assembly, photo-responsive phase behavior and variable tensile property of azobenzene-containing ABA triblock copolymers

Abstract

A series of triblock copolymers with liquid crystalline (LC) poly{6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate} (PMMAZO) as the end blocks and rubbery poly(n-butyl acrylate) (PnBA) as the midblock were synthesized. The effect of the interplay between the LC ordering and microphase separation on the hierarchical assembly of the triblock copolymers was studied. It is found that microphase separation at a larger scale can affect the LC ordering at a smaller scale, such as the stacking of the LC moieties, LC temperature and the domain size of the LC phase. On the other hand, alteration of the LC ordering, such as isotropization and smetic-to-nematic transition, may also lead to an order-order transition (OOT) or change in the long period of the microphase-separated structure. UV light can trigger the isomerization of the azobenzene LC moieties, which can be further amplified and exerts an effect on the microphase separation behavior, including the regularity of the microphase-separated structure and the OOT. The triblock copolymers also exhibit light-variable tensile properties. The results reveal that the phase behavior and mechanical properties of this type of triblock copolymer can be readily regulated by light, thus it may be used as smart and functional thermoplastic elastomer.

Hierarchical Structures with Double Lower Disorder-to-Order Transition and Closed-Loop Phase Behaviors in Charged Block Copolymers Bearing Long Alkyl Side Groups

“…For example, Hamley et al observed that the LC ordering of the side groups was suppressed in a BCP with a high fraction of the amorphous block . By contrast, we found that the clear point of the LC side groups was slightly increased in microphase-separated BCPs, as compared with the corresponding homopolymer …”

Experimental and Quantum Chemical Studies on the Corrosion Inhibition of Mild Steel By 2-((Thiophen-2-Ylmethylene) Amino)Benzenethio in 1M HCl

“…Mild steel coupons texture of C (0.21%), Si (0.38%), Mn (0.05%), P (0.09%), Al (0.01%), and Fe (99.21%) were utilized for weight loss investigations. The coupons were cleaned according to the standard procedure to be specific ASTM G1-03 (13)(14)(15)(16)(17)(18)(19)(20)(21)(22). In a typical methodology, coupons were suspended volume 200 mL of a corrosive solution (in duplicate) to try or not of 2-((thiophen-2-ylmethylene) amino) benzenethiol.…”

Regulation of the self-assembly morphology of azobenzene-bearing double hydrophobic block copolymers in aqueous solution by shifting the dynamic host–guest complexation

“…It is found that azobenzene (azo) is especially advantageous to induce a dramatic structural change due to its photo-induced reversible trans-cis isomerization. [22][23][24][25][26][27][28] The change at the molecular level triggered by light can be amplified, leading to a change in the structure at a larger scale and in the macroscopic properties. The phototriggered self-assembly behaviors of azo-containing BCPs have been widely investigated.…”