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

In this work syntheses of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) with different molecular weights were carried out in ethanol by distillation precipitation polymerization (DPP) technique. The synthesized polymers were fully characterized by attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and size exclusion chromatography (SEC) techniques. The lower critical solution temperatures (LCST) of the polymers were determined with differential scanning calorimetry (DSC). A simple and versatile method for the in situ synthesis and grafting of PNIPAM on mesoporus silica nanoparticles (MSNs) with improved control over quantitative grafting is devised. The PNIPAM grafted MSNs were characterized with ATR-FTIR, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses. From the results obtained it is showed that quantitative grafting of PNIPAM on MSNs from 1 to 20 % by weight can be tuned by manipulating the in situ DPP reaction conditions.