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

Abstract

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 spectroscopy, and size exclusion chromatography techniques. The lower critical solution temperatures of the polymers were determined with differential scanning calorimetry. 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, transmission electron microscopy, and dynamic light scattering 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. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44181.

The evaluation of temperature and pH influences on equilibrium swelling of poly(n-isopropylacrylamide-co-acrylic acid) hydrogels

“…The result of the amide group vibrating in the structure of NIPAM is absorption band of strong intensity at 1658 (amide band I) and 1550 cm -1 (amide band II), which is in accordance with literature data of other authors [36]. Absorption bands of strong intensity with maximum at 1619 cm -1 in FTIR spectrum of monomer ( Figure 1A) has been assigned to valence vibrations of double bonds, ν(C=C) [37]. In FTIR spectrum of NIPAM only one absorption band has been observed from deformation vibrations of C-H bonds from isopropyl group, CH(CH 3 ) 2 , at 1368 cm -1 .…”

Surrounding Interactions on Phase Transition Temperature Promoted by Organometallic Complexes in Functionalized Poly(N‐isopropylacrylamide‐co‐dopamine methacrylamide) Copolymers

“…The DMA content can be estimated by comparison of the protons belonging to the benzene ring of DMA and the proton of –CH–, located in NH‐CH‐(CH 3 ) 2 groups, related to NIPAM, which are placed at 6.7 and 3.8 ppm, respectively (Figure 1d). [ 32,33 ] The total amount of comonomer content can be established through Equation (1) according to the number of hydrogens involved where the integral areas of DMA (Area DMA ) and NIPAM (Area NIPAM ) are defined in Figure 1d and the comonomer content is called [DMA]. The different comonomer contents are displayed in Table 3, where a wide range of DMA compositions is exhibited.…”

Electrospun thermosensitive hydrogel scaffold for enhanced chondrogenesis of human mesenchymal stem cells

“…The most prominent peaks, PEG-DMA's peak associated with -H of the PEG main chain located at 3.6 ppm (labeled as 1 in Fig. 2b) [22,34], as well as NIPAAm's C-H proton at 3.8 ppm and methylene proton peak at 1.1 ppm (labeled as 2 and 3, respectively) [22,35], were all present in PEG-PNIPAAm. The intensity ratio of the peaks for 1-ethylene protons associated with NIPAAm and 1-ethylene protons associated with PEG-DMA were used to determine an approximate ratio of 650:1 between PNIPAAm and PEG crosslinking chains in the synthesized polymer.…”