Structure of poly(N-isopropylacrylamide) brushes and steric stability of their grafted cellulose nanocrystal dispersions

Hemraz, Usha D.; Lu, Ang; Sunasee, Rajesh; Boluk, Yaman

doi:10.1016/j.jcis.2014.05.011

Cited by 71 publications

(62 citation statements)

References 44 publications

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“…Since the width of the CNC nanoparticles and the derivatives were fairly uniform, it was possible to measure the diameters before and after functionalization. The STEM images ( Figure 4A,B and Figure S4A, Supporting Information) revealed a diameter of 11.8 ± 2.4 nm for the unmodified CNC, 40 16.4 ± 2.7 nm for CNC-gpoly(AEMA)-1, and 14.8 ± 1.7 nm for CNC-g-poly(AEM)-1, thus confirming the successful grafting. Next, the surface charge of the nanofibers was evaluated upon incubation of the colloidal suspensions of CNCs and the modified derivatives with AuNPs.…”

Section: ■ Results and Discussionmentioning

confidence: 63%

Cationic Poly(2-aminoethylmethacrylate) and Poly(N-(2-aminoethylmethacrylamide) Modified Cellulose Nanocrystals: Synthesis, Characterization, and Cytotoxicity

et al. 2014

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Section: ■ Results and Discussionmentioning

confidence: 63%

Cationic Poly(2-aminoethylmethacrylate) and Poly(N-(2-aminoethylmethacrylamide) Modified Cellulose Nanocrystals: Synthesis, Characterization, and Cytotoxicity

et al. 2014

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“…The transparent aqueous solution containing the NIPAM macro-CTA became opaque at temperatures higher than the LCST, as illustrated in Figure 3 displaying the results obtained from UV spectroscopic analyses. However, the LCST was 34.4 • C, almost 2 • C higher than that of the NIPAM macro-CTA (32.6 • C), implying that the higher LCST of the poly(NIPAM-b-Azo) micelle compared with that of the NIPAM macro-CTA homopolymer was potentially caused by steric repulsion of the poly(NIPAM) chains tethered to the micelle's hydrophobic azobenzene core [50]. Subsequently, the influence of temperature on the fluorescence of the poly(NIPAM-b-Azo) in solution at 25 and 40 °C was investigated.…”

Section: Thermoresponsive Properties Of Polymersmentioning

confidence: 91%

Synthesis and Self-Assembly of Multistimulus-Responsive Azobenzene-Containing Diblock Copolymer through RAFT Polymerization

et al. 2019

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This paper gathered studies on multistimulus-responsive sensing and self-assembly behavior of a novel amphiphilic diblock copolymer through a two-step reverse addition-fragmentation transfer (RAFT) polymerization technique. N-Isopropylacrylamide (NIPAM) macromolecular chain transfer agent and diblock copolymer (poly(NIPAM-b-Azo)) were discovered to have moderate thermal decomposition temperatures of 351.8 and 370.8 °C, respectively, indicating that their thermal stability was enhanced because of the azobenzene segments incorporated into the block copolymer. The diblock copolymer was determined to exhibit a lower critical solution temperature of 34.4 °C. Poly(NIPAM-b-Azo) demonstrated a higher photoisomerization rate constant (kt = 0.1295 s−1) than the Azo monomer did (kt = 0.088 s−1). When ultraviolet (UV) irradiation was applied, the intensity of fluorescence gradually increased, suggesting that UV irradiation enhanced the fluorescence of self-assembled cis-isomers of azobenzene. Morphological aggregates before and after UV irradiation are shown in scanning electron microscopy (SEM) and dynamic light scattering (DLS) analyses of the diblock copolymer. We employed photoluminescence titrations to reveal that the diblock copolymer was highly sensitive toward Ru3+ and Ba2+, as was indicated by the crown ether acting as a recognition moiety between azobenzene units. Micellar aggregates were formed in the polymer aqueous solution through dissolution; their mean diameters were approximately 205.8 and 364.6 nm at temperatures of 25.0 and 40.0 °C, respectively. Our findings contribute to research on photoresponsive and chemosensory polymer material developments.

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“…The detailed descriptions of the surface preparation and characterizations of CNC‐1, CN2, and CNC‐ g were given in another manuscript, which is submitted for publication. The degree of polymerization (DP) of grafted polystyrene on CNC surfaces was not measured, however based on previously reported values it is expected to be around 100 …”

Section: Methodsmentioning

confidence: 99%

Fabrication of oriented electrospun cellulose nanocrystals–polystyrene composite fibers on a rotating drum

Kalantari

McDermott

Ayranci

et al. 2020

J of Applied Polymer Sci

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Nitrobenzene (CNC-1), trifluoromethyl benzene (CNC-2) modified and polystyrene-grafted (CNC-g) cellulose nanocrystals in polystyrene (PS)-N,N dimethylformamide (DMF) solutions were electrospun and collected as stretched and aligned fibers on a rotating drum. Scanning electron microscope pictures showed significant alignment in the case of unmodified and nitrobenzene-modified CNC-1/ PS nanocomposite fibers once the linear speed of rotor reached to 15 m s −1 . Fiber diameter decrease was more strong with rotor speed increase in the case of trifluoromethyl benzene modified (CNC-2) and polystyrene-grafted (CNC-g) cellulose nanocrystals/PS systems. Dynamic mechanical analysis including storage and elastic modulus of electrospun-oriented fibers were performed on surface-modified and polymer-grafted CNC/PS samples. According to α transition peak, the increase in the glass-transition temperature with filler concentration was the highest in polymer-grafted CNC-g/PS composite fibers. It was due to the interpenetration of grafted polymer brushes and free polymer chains in continuous phase and resulted in restrictions of motions of polymer chains in the PS matrix. The elastic moduli of nitrobenzene (CNC-1) and trifluoromethyl benzene (CNC-2)-modified CNC-filled PS composite fibers agreed well with percolation model, which indicates the CNC-CNC interactions and network formation with an increase in concentration. Magnitude of the elastic modulus of polymer grafted CNC-g at 0.33 vol % in PS was significantly higher than the prediction from percolation theory. It was due the immobilized polymer chains around CNC-g particles. However, grafted polymer chains, at higher CNC concentrations acted like stickers among CNC particles and caused CNC agglomerates with entrapped free polystyrene from the matrix, thus caused a decrease in the elastic modulus.

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Structure of poly(N-isopropylacrylamide) brushes and steric stability of their grafted cellulose nanocrystal dispersions

Cited by 71 publications

References 44 publications

Cationic Poly(2-aminoethylmethacrylate) and Poly(N-(2-aminoethylmethacrylamide) Modified Cellulose Nanocrystals: Synthesis, Characterization, and Cytotoxicity

Cationic Poly(2-aminoethylmethacrylate) and Poly(N-(2-aminoethylmethacrylamide) Modified Cellulose Nanocrystals: Synthesis, Characterization, and Cytotoxicity

Synthesis and Self-Assembly of Multistimulus-Responsive Azobenzene-Containing Diblock Copolymer through RAFT Polymerization

Fabrication of oriented electrospun cellulose nanocrystals–polystyrene composite fibers on a rotating drum

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