Linear Cyclobutane-Containing Polymer Synthesis via [2 + 2] Photopolymerization in an Unconfined Environment under Visible Light

Abstract

The [2 + 2] photopolymerization of diolefinic monomers is an appealing approach for the construction of polymeric materials. Herein, we demonstrate that the establishment of an effective donor–acceptor conjugation by introducing electron-donating alkoxy groups at appropriate positions of the benzene ring could activate p-phenylenediacrylate (PDA), thus enabling the development of the first solution [2 + 2] photopolymerization of such monomers under the irradiation of visible light. Variation on the alkoxy groups and the ester parts could allow access to a series of linear cyclobutane-containing polymer products with high molecular weight (up to 140 kDa) and good solubility in common solvents. Further, temporal control and postpolymerization modification with preinstalled pendant CC bonds via thiol–ene click reaction are also demonstrated with this [2 + 2] photopolymerization system.

Thermoresponsive Fluorescent Microgels through In Situ [2 + 2] Photocycloaddition Cross-Linking of Thermally Induced Aggregates of Dendrimers

“…SEC measurements showed that molecular weight increased from 2.9 to 4.6 kDa after UV irradiation of Den-TPA in water at 20 °C for 5 min (Figure S3). The above results demonstrate the cinnamate moieties in Den-TPA were efficiently photodimerized below its T cp to form soluble oligo­(dendrimer)­s, which is similar as [2 + 2] photocycloaddition polymerization of diolefin monomers in solutions. , It is worthy to mention that the photocycloaddition of Den-TPA below its T cp did not generate the well-defined microgels despite the amphiphilic aggregation in water. This may be because the associative interaction among Den-TPA molecules below T cp is so weak and dynamic that cannot facilitate the microgel formation .…”

Photocatalytic Metal‐Free Radical Hydrosilylation for Polymer Functionalization†

“…Photocatalysis has attracted great attention where the light is abundant, mild, cheap, environmentally friendly, and capable of spatiotemporal control. [ 21‐26 ] In recent years, the focus has been placed on adapting photocatalytic reactions in polymer synthesis, such as post‐modification or polymerization, [ 22,27‐30 ] and the organic reaction needs to be highly reactive and efficient due to the reduced mobility of active species in the polymer chains. [ 22 ] Therefore, some efficient photo‐induced reactions have been used to post‐modify polymers.…”

Carboxylic acid and metal ion co-driven assembly of triene coordination polymers for [2 + 2] photocycloaddition

“…However, in solution and bulk samples of organic molecules, it is difficult to obtain the target photoreaction products by controlling the specific orientations and distances of CC double bonds, and only a few types of photocycloaddition products can be generated. 8–10…”

“…However, in solution and bulk samples of organic molecules, it is difficult to obtain the target photoreaction products by controlling the specific orientations and distances of CvC double bonds, and only a few types of photocycloaddition products can be generated. [8][9][10] Coordination polymers (CPs) are constructed of metal ions or metal cluster cores that are coordinated by organic ligands, and they are highly crystalline. 11,12 Upon self-assembly, the position of each atom in these structures is well determined and can be fine-tuned by structural design.…”