Thermosensitive fibres of lyocell/poly(N -isopropylacrylamide): multiparametric analysis for studying the graft copolymerization

Abstract

The thermosensitive properties of the hydrogel poly(N-isopropylacrylamide) (pNIPAAm) together with the good mechanical properties of lyocell fibres make a combination of the two to be thought of as a smart textile. In the present study the optimal values of various parameters that control the grafting process of pNIPAAm onto lyocell fibres were determined considering the influence of the interaction between them. The copolymerization of pNIPAAm hydrogel onto lyocell fibres was performed in aqueous acidic medium using cerium(IV) as initiator. An experimental design was planned in order to study the effect of the interactions between some variables that affect the kinetics of the graft copolymerization: the cerium(IV) initiator concentration, the N-isopropylacrylamide (NIPAAm) monomer concentration and the liquor fibre-to-bath ratio. The results show that the interaction between the concentrations of NIPAAm and the initiator significantly affects the degree of grafting (DG), the optimum values being 1250 and 12.25 mmol L−1, respectively. In contrast, the liquor ratio parameter shows no significant interaction with the other two variables studied, meaning that it acts independently but showing a proportional relationship with respect to the DG obtained. In addition, the presence of pNIPAAm in the copolymer obtained was confirmed by Fourier transform infrared spectral analysis. Moreover, the water sorption capacity, depending on the temperature, of the lyocell/pNIPAAm copolymer was studied, with an increase being observed when the DG is higher than 60% and also increasing with the temperaturePostprint (published version

Thermo-responsive poly(N-isopropylacrylamide)-grafted hollow fiber membranes for osteoblasts culture and non-invasive harvest

“…2. The cellulose acetate HFM spectra showed significant absorption bands at 3350 cm −1 (-OH stretching), 2900 cm −1 (-CH stretching), 1420 cm − 1 (-CH 2 bending), 1371 cm − 1 (-CH bending), 1151 cm − 1 (C-C stretching), 1016 cm −1 (-CH2 wagging) and 893 cm −1 (C1 frequency), which were the characteristics of the main constituents of HFM regenerate cellulose: crystalline cellulose II and amorphous cellulose [25]. After grafted with PNIPAAm, the FTIR spectra of HFMs showed characteristic peaks at 1650 and 1550 cm −1 , corresponding to -C=O stretching and -NH bending of secondary amides, respectively.…”

“…As an initiator, CAN leads to formation of free radicals during oxidation of C2 and C3 hydroxyl groups of anhydro-Dglucose of cellulose, which then initiates the graft polymerization of NIPAAm vinyl monomer ( Fig. 1) [19][20][21][22].…”

“…PNIPAAm-grafted HFMs were prepared by free radical polymerization according to the reported protocols with some modifications [19,20]. A typical procedure (e.g., HFMs-0.2, 0.2 represents that the feed concentration of NIPAAm is 0.2 M) was as follows: alkaline treated HFMs (abbreviated as HFMs-0, single length: 4 cm, diameter: 175 μm, total number: 500) were loaded into a round bottom flask equipped with a three-way stopcock, in which 25 mL nitric acid solution ([HNO 3 ] = 0.1 M) was added, followed by bubbling with nitrogen for 5 min to deoxygenate the reaction mixture.…”

Novel Synthesis Pathways for PNIPAAm-Based Hydrogels and Their Application in Thermosensitive Textiles

“…An interesting study conducted by Erencia et al shed a light on another aspect of PNIPAAmbased smart textile fabrication [54]. The approach used in this work does not imply treatment of the textile surface but the textile fibers (lyocell) that were grafted with PNIPAAm.…”