Sustainable Light‐Stimulated Synthesis of Cross‐Linked Polymer Microparticles

Abstract

The increasing demand for crosslinked polymer microparticles (PMPs) in advanced applications requires the development of new sustainable methods which can reduce the impact of the polymerization process on the environment. This research reports a new environmentally-friendly light-assisted polymerization method for the synthesis of highly cross-linked polymer microspheres by combining light-induced [2+2] cycloadditions with dispersion polymerization. Using naturally-occurring coumarin as reactive moieties, this method allows the synthesis of highly crosslinked PMPs in the presence of UV light at room temperature without initiator. The effect of the reaction parameters such as monomer concentration, stabilizer and reaction time on the particle size and yield are investigated using a number of techniques including Fourier transform infrared spectroscopy, solid-state 13 C nuclear magnetic resonance spectroscopy, and scanning electron microscopy. The results show the formation of highly crosslinked porous microspheres which demonstrate good thermal stability.

Synthesis and Controlled Cargo Release of Novel Photoresponsive Polysiloxane‐Based Single‐Chain Nanoparticles

“…[25] With a wide variety of UV-triggered reaction choices, the photoreversible [2+2] reaction is favorable since minimal to no by-products are formed; it is photoreversible; reaction efficiencies are high; and it can be carried out in the solution or solid state. [26][27][28] The forward [2+2] reaction proceeds via UV-induced formation of a cyclobutane ring between two neighboring 𝜋-systems, which can be reversed by a UV irradiation of a lower wavelength. These advantages make a compelling case for the use of [2+2] reactions in a SCNP formation and controlled release study, as they can be used to not only form SCNPs during the encapsulation process, but to also be used as a phototrigger for the release of the encapsulated cargo molecules, thereby tackling two processes with one mechanism.…”

Photo-responsive lignin fragment-based polymers as switchable adhesives

“…11 Coumarin and cinnamic acid moieties can be utilized to produce photo-responsive polymers for several valueadded applications, such as self-healing, photo-resist, liquid crystals and other smart materials. [12][13][14] Photo-reactive reusable adhesives are one such application area that can be very effective in repairing and recycling of polymer materials and reduce waste to an extent where conventional single-use adhesives fail. 15 Azo polymers have been explored to synthesize light-switchable adhesives using cis-trans photo-isomerization.…”

Eco-Friendly Photoreversible Adhesives Derived from Coumarin-Functionalized Epoxy Soybean Oil

“…Moreover, it lowers the cost of producing polymer materials by utilizing low-cost light sources like laser and light-emitting diodes . Among the light-stimulated reactions, the reversible [2 + 2] cycloaddition reactions have attracted much attention as they do not require any initiators or catalysts and no byproducts are formed. − However, only a few compounds can undergo this type of reaction, including coumarin, cinnamic acid, and thymine . Coumarin is a plant-derived compound that undergoes dimerization in the presence of 365 nm light and from a cyclobutane ring, while irradiating with 254 nm of light cleaves the cyclobutane rings to reform the double bonds .…”

“…Coumarin is a plant-derived compound that undergoes dimerization in the presence of 365 nm light and from a cyclobutane ring, while irradiating with 254 nm of light cleaves the cyclobutane rings to reform the double bonds . The reversible light-stimulated [2 + 2] chemistry of coumarin has been utilized to synthesize photoresists, self-healing coatings, liquid crystals, polymer particles, and hydrogels . Xu et al designed and synthesized a coumarin-functionalized polyester and studied its adhesive performance .…”