Controlled post‐synthesis grafting of thermoresponsive poly(N‐isopropylacrylamide) on mesoporous silica nanoparticles

Abstract

Ordered mesoporous silica nanoparticles with pore diameter of 5 nm were synthesized by modification of the sol‐gel synthesis method. Post‐synthesis two‐step grafting of thermoresponsive poly(N‐isopropylacrylamide) inside the mesopores of the nanoparticles was carried out by distillation–precipitation polymerization of the methacryloxy‐functionalized mesoporous nanoparticles with N‐isopropylacrylamide monomer. A precise control on the quantity of the grafted polymer was achieved by changing the ratio of monomer to methacryloxy‐functionalized nanoparticles. The polymer‐grafted hybrid nanoparticles obtained were fully characterized by infrared spectroscopy, X‐ray diffraction, dynamic light scattering, transmission electron microscopy, thermal, and gas‐volumetric analyses, which clearly showed presence and thermoresponsive behavior of the polymer inside the mesopores with the preservation of the characteristic mesoporous structure of the nanoparticles. Copyright © 2015 John Wiley & Sons, Ltd.

Synthesis of poly(N‐isopropylacrylamide) by distillation precipitation polymerization and quantitative grafting on mesoporous silica

“…The synthesis of MSNs was carried out following the same procedure already reported elsewhere . CTAB was used as cationic micelle forming templating agent, while TMB was used as the micelle core swelling agent.…”

“…Some of the interesting reports about DPP include synthesis of monodisperse poly(methacrylic acid) microspheres and synthesis of superhydrophobic fluorinated polystyrene microspheres . Instead reports about polymer grafting on nanoparticles by DPP include polymerization of methacrylic acid on PMMA/TiO 2 composite nanospheres, synthesis of PNIPAM‐grafted silica and mesoporous silica nanoparticles, DPP‐mediated grafting of poly(4‐vinyl benzylchloride) for the generation of chlorine functionalized Fe 3 O 4 hybrid composites, synthesis of poly(acrylic acid)‐grafted magnetite nanoparticles for the generation of magnetic metal–organic framework nanospheres, preparation of erythromycin molecularly imprinted polymers, synthesis of metronidazole‐imprinted polymers, and boronate core–shell polymer nanoparticles for glycoprotein recognition via combined DPP and RAFT media precipitation polymerization . All these examples mentioned show the versatility of DDP technique in synthesis and grafting of various polymers.…”

“…All these examples mentioned show the versatility of DDP technique in synthesis and grafting of various polymers. So although initially DPP technique was reported for the synthesis of microspheres of polymers it is revealed that it also works well for the synthesis and grafting of polymers, especially PNIPAM, on various nanoparticles …”

Thermoresponsive copolymer-grafted SBA-15 porous silica particles for temperature-triggered topical delivery systems

“…In general silanol groups do not interfere with the chain propagation during the polymer formation. In fact, their reactivity is considerable in aqueous solvents (where they dissociate, with an isoelectric point around 2-3), but is much less in anhydrous organic solvents [23]. Structure of the polymer and its grafting by using the reactivity of surface silanols inside the pores are shown in Figure 4b.…”

Thermally Stable and Processable Organic-Inorganic Hybrid Material

“…Other approaches were grafting of silica onto PNIPAM particles using RAFT polymerization and radical polymerization. These grafted materials have several applications in various fields [21][22][23].…”