Photochromic Polyamide 6 Based on Spiropyran Synthesized via Hydrolyzed Ring-Opening Polymerization

Abstract

We report photochromic polyamide 6 (PA6) which was synthesized by hydrolyzed ring-opening polymerization of ε-caprolactam with spiropyran (SP) embedded in the polymer chains. It indicated that crystallinity degree of the resulting copolymers was decreased since only PA6 segments can crystallize with increasing content of SP modifier. Meanwhile, toughness of photochromic PA6 was decreased. The photochromic property analysis indicated that the sample with more flexibility and more content of SP was more sensitive to UV light at the beginning of irradiation than other samples and its color after being irradiated for 1 min tended to reddish. Investigation revealed that the UV-vis absorbance of SP-PA6-3 had negligible decay after 10 cycles, which indicated SP-modified PA6 possessed excellent photoresponse reversibility and fatigue resistance.

Light, Heat, and Force‐Responsive Polyolefins

“…[ 45 , 49 , 50 ] These newly developed functional polyolefins are among the best materials with a great balance between high stress and high toughness (Figure 2I and Figure S21 , Supporting Information). [ 51 , 52 , 53 , 54 , 55 , 56 , 57 ]…”

Electrocarboxylation of Spiropyran Switches through Carbon‐Bromide Bond Cleavage Reaction

“…For most of these applications, the photoswitchable molecules must be covalently attached to the final materials, such as polymers, [19–21] nanoparticles, [22,23] biomacromolecules [24,25] and surfaces, [26,27] which requires the introduction of suitable groups in spiropyrans to ensure chemical functionalization. Carboxylic acid groups are amongst the most preferred for this purpose, as they confer molecules with a broad reactivity that enables the covalent bonding to substrates by simple coupling reactions (e. g., amide bond formation) [26,28,29] .…”

“…[12,13] Because of the large change in properties upon photoisomerization, spiropyrans have been exploited for the preparation of a wide variety of smart functional materials whose properties can be very precisely controlled using light as an external stimulus. [14][15][16][17][18] For most of these applications, the photoswitchable molecules must be covalently attached to the final materials, such as polymers, [19][20][21] nanoparticles, [22,23] biomacromolecules [24,25] and surfaces, [26,27] which requires the introduction of suitable groups in spiropyrans to ensure chemical functionalization. Carboxylic acid groups are amongst the most preferred for this purpose, as they confer molecules with a broad reactivity that enables the covalent bonding to substrates by simple coupling reactions (e. g., amide bond formation).…”