skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Green synthesis of cellulose graft copolymers for anion exchange water purification
A cellulose graft copolymer (cellulose nanoresin) was synthesized by the all-aqueous functionalization of cellouronic acid with poly (vinyl benzyl trimethyl ammonium chloride) (poly(vbTMAC)). Cellulose was oxidized using the highly reported 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated selective C-6 oxidation reaction. Fischer–Speier esterification of cellouronic acid was used to graft poly(vbTMAC) to the cellulosic backbone in a facile click-like mechanism. Synthesis of cellulose nanoresin was confirmed using dynamic light scattering and zeta potential measurements. Conductometric titration was used to determine the carboxylate content of cellouronic acid and the percent functionalization of the cellulose nanoresin, which was 1.69 ± 0.03 mmol/g and 61.2 ± 4%, respectively. Using a disodium fluorescein (NaFL) surrogate adsorbate, the maximum adsorption capacity of CNR was measured to be 26.8 ± 1.3 mg NaFL per gram of CNR with a Langmuir equilibrium binding constant of Ks = 10.5 ± 2 ppm−1. When examined as a thin film membrane, a breakthrough study of CNR showed that equilibrium loading was achieved in less than 30 s, and that > 90% of loading occurred in under 5 s. This data suggests that these films can be used as contact resins for anion-exchange water purification. We show in this work that these films maintain > 99% of loading performance over 40 trials of regeneration and reuse, meaning that these films are green and regenerable. Initial testing shows that CNR is effective at the removal of perfluorooctane sulfonate (PFOS) from water to below our limit of detection of 100 ppt.  more » « less
Award ID(s):
2141056
PAR ID:
10483679
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
Springer Nature
Date Published:
Journal Name:
Cellulose
Volume:
30
Issue:
17
ISSN:
0969-0239
Page Range / eLocation ID:
11055 to 11069
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, Macromolecular Rapid Communications)
    Abstract Lignin is an aromatic‐rich biomass polymer that is cheap, abundant, and sustainable. However, its application in the solid electrolyte field is rare due to challenges in well‐defined polymer synthesis. Herein, the synthesis of lignin‐graft‐poly(ethylene glycol) (PEG) and its conductivity test for a solid electrolyte application are demonstrated. The main steps of synthesis include functionalization of natural lignin's hydroxyl to alkene, followed by graft‐copolymerization of PEG thiol to the lignin via photoredox thiol‐ene reaction. Two lignin‐graft‐PEGs are prepared having 22 wt% lignin (lignin‐graft‐PEG 550) and 34 wt% lignin (lignin‐graft‐PEG 2000). Then, new polymer electrolytes for conductivity tests are prepared via addition of lithium bis‐trifluoromethanesulfonimide. The polymer graft electrolytes exhibit ionic conductivity up to 1.4 × 10−4 S cm−1 at 35 °C. The presence of lignin moderately impacts conductivity at elevated temperature compared to homopolymer PEG. Furthermore, the ionic conductivity of lignin‐graft‐PEG at ambient temperature is significantly higher than homopolymer PEG precedents. 
    more » « less
  2. ; ; ; (, ACS Biomaterials Science & Engineering)
    Clinical use of polymeric scaffolds for tissue engineering often suffers from their inability to promote strong cellular interactions. Functionalization with biomolecules may improve outcomes; however, current functionalization approaches using covalent chemistry or physical adsorption can lead to loss of biomolecule bioactivity. Here, we demonstrate a novel bottom-up approach for enhancing the bioactivity of poly(l-lactic acid) electrospun scaffolds though interfacial coassembly of protein payloads with silk fibroin into nanothin coatings. In our approach, protein payloads are first added into an aqueous solution with Bombyx mori-derived silk fibroin. Phosphate anions are then added to trigger coassembly of the payload and silk fibroin, as well as noncovalent formation of a payload-silk fibroin coating at poly(l-lactic) acid fiber surfaces. Importantly, the coassembly process results in homogeneous distribution of protein payloads, with the loading quantity depending on payload concentration in solution and coating time. This coassembly process yields greater loading capacity than physical adsorption methods, and the payloads can be released over time in physiologically relevant conditions. We also demonstrate that the coating coassembly process can incorporate nerve growth factor and that coassembled coatings lead to significantly more neurite extension than loading via adsorption in a rat dorsal root ganglia explant culture model. 
    more » « less
  3. ; (, Polymer Chemistry)
    Terminal silanol groups on the glass surface were used for the chemical bonding of α-bromo amide as the initiator for surface initiated Cu(0)-mediated living radical polymerization (LRP) to graft well-defined poly(butyl arylate) (PBA) and poly(2,2,2-trifluoroethyl methacrylate) (PTFEM) brushes on the glass surface. A grafting to methodology was also performed by the modification of the glass surface using a thiosilane agent and performing a thio-bromo click reaction in the presence of PBA and PTFEM synthesized via Cu(0)-mediated LRP. Furthermore, a one-pot grafting to method was developed that proved a facile, fast, and efficient method for grafting a bromo-terminated polymer to the glass surface in one step. All glass slides were characterized using ATR-FTIR and UV-vis spectroscopy, water contact angle measurements and SEM. The surface topology and roughness of selected samples were analyzed using AFM. Results show that an ultrathin layer of a polymer with nanoscale features and high roughness was chemically grafted to the glass surface without compromising glass transparency. These methodologies can be used to graft well-defined polymers with different functionalities on the glass surface. 
    more » « less
  4. ; ; ; ; ; (, Green Chemistry)
    Mechanical decrystallization and water-promoted recrystallization of cellulose were studied to understand the effects of cellulose crystallinity on reaction engineering models of its acid-catalyzed hydrolysis. Microcrystalline cellulose was ball-milled for different periods of time, which decreased its crystallinity and increased the glucose yield obtained from acid hydrolysis treatment. Crystallinity increased after acid hydrolysis treatment, which has previously been explained in terms of rapid hydrolysis of amorphous cellulose, despite conflicting evidence of solvent promoted recrystallization. To elucidate the mechanism, decrystallized samples were subjected to various non-hydrolyzing treatments involving water exposure. Interestingly, all non-hydrolyzing hydrothermal treatments resulted in recovery of crystallinity, including a treatment consisting of heat-up and quenching that was selected as a way to estimate the crystallinity at the onset of hydrolysis. Therefore, the proposed mechanism involving rapid hydrolysis of amorphous cellulose must be incomplete, since the recrystallization rate of amorphous cellulose is greater than the hydrolysis rate. Several techniques (solid-state nuclear magnetic resonance, X-ray diffraction, and Raman spectroscopy) were used to establish that water contact promotes conversion of amorphous cellulose to a mixture of crystalline cellulose I and cellulose II. Crystallite size may also be reduced by the decrystallization-recrystallization treatment. Ethanolysis was used to confirm that the reactivity of the cellulose I/cellulose II mixture is distinct from that of truly amorphous cellulose. These results strongly point to a revised, more realistic model of hydrolysis of mechanically decrystallized cellulose, involving recrystallization and hydrolysis of the cellulose I/cellulose II mixture. 
    more » « less
  5. ; ; ; (, SPE Polymers)
    Abstract Nanocrystalline cellulose (NCC), which is a known crystal nucleating agent, is utilized to improve poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) thermal properties. Since NCC aggregation in PHBV negatively affects composite properties and processability, NCC crystal nucleation effectiveness was examined at low concentrations (<1%) under isothermal and nonisothermal conditions. NCC was dispersed in PHBV solutions using a solvent exchange method and then cast into films. We found that NCC was an effective nucleating agent in amounts as low as 0.25%, resulting in an increase in PHBV crystallization rate by more than 50%. However, increasing to 1% NCC resulted in aggregation in PHBV, with the NCC becoming less effective compared to lower NCC concentrations. In an attempt to improve NCC dispersion, we added cellulose acetate (CA) or stearic acid (SA) to the casting solution, anticipating that CA or SA would preferentially adsorb on the NCC. With such pretreatment, dispersion was indeed improved but NCC became less effective as a PHBV nucleating agent. This work shows the advantage of using low NCC concentrations (<0.5%) for promoting PHBV crystallization, but the lack of improved nucleation upon addition of CA and SA supports the importance of NCC surface accessibility. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email