Dual thermo- and light-responsive nanorods from self-assembly of the 4-propoxyazobenzene-terminated poly(N-isopropylacrylamide) in aqueous solution

Multi-responsive fluorescence of amphiphilic diblock copolymer containing carboxylate azobenzene and N-isopropylacrylamide

“…In contrast, under base condition, photoisomerization of azobenzene groups can cause obvious dipole change which increased the aggregate size upon UV irradiation. Recently, Xue et al reported very similar results when studying the self-assembly properties of an azo-terminating PNIPAm in water [53]. It is well-known that isomerization of azobenzene from trans to cis often increases its dipole moment.…”

Preparation of Thermoresponsive Polymer Nanogels of Oligo(Ethylene Glycol) Diacrylate-Methacrylic Acid and Their Property Characterization

“…In fact, hydrogel particles with their R h around 10 nm, determined by DLS, were often reported. Diverse examples are available, such as polyacrylamide above its UCST in aqueous alcohol solutions [ 43 ] and 4-propoxyazobenzene-terminated PNIPAM in aqueous solution below its LCST [ 47 ]. And R h as small as 2 to 3 nm was reported for an OEG-based responsive polymer below its LCST [ 48 ].…”

Light and Temperature as Dual Stimuli Lead to Self-Assembly of Hyperbranched Azobenzene-Terminated Poly(N-isopropylacrylamide)

“…Hyperbranched polymers were previously prepared through controlled/“living” radical polymerization in the presence of branching agents [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ] and hence it was hypothesized that the hyperbranched poly( N -isopropylacrylamide) (PNIPAM) could also be synthesized by atom transfer radical polymerization (ATRP) of PNIPAM and N , N ′-methylenebis(acrylamide) (MBA) [ 46 , 47 , 48 ]. Therefore, the ATRP of NIPAM using different azobenzene-functional initiators was carried out using Scheme 1 under the condition of isopropyl alcohol:water = 2:1 (m/m), T = 25 °C, and [NIPAM] 0 :[MBA] 0 :[initiator] 0 :[CuCl] 0 :[Me 6 TREN] 0 = 30:0.9:1:1:3.…”

“…, the difference in temperature (ΔT) was −2 °C with HBPNIPAM-Azo-OC 3 H 7 solution (as shown in Table 1 ), which was due to changes in aggregates during UV irradiation. The initially formed spherical micelles completely transformed to nanorods of larger size, which are more responsive to temperature [ 48 ]. Similarly, when the number of multimolecular aggregates in the HBPNIPAM-Azo-OCH 3 solution increased significantly, there was a small decrease in the LCST value (24.5 °C) compared to that of the initial state (25.5 °C), i.e.…”