An approach to the knowledge of the graft polymerization of acrylic monomers onto polysaccharides using Ce(IV) as initiator

Gurruchaga, M.; Goñi, Isabel; Vazquez, Mariela; Valero, Miguel Ángel Molina; Guzmán, G. M.

doi:10.1002/pol.1989.140270501

Cited by 17 publications

(6 citation statements)

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“…Several research articles have been published reporting on the graft copolymerization of various acrylic monomers onto polymer backbone containing hydroxyl groups, using Ce(IV) ion as an initiator 25–27. The grafting was assumed to proceed via a redox mechanism in three steps: (1) the solvation of water to chitosan, (2) the formation of the complex between solvated chitosan and Ce(IV), and (3) grafting initiation by radicals from the complex.…”

Section: Resultsmentioning

confidence: 99%

Thermo- and pH-responsive behaviors of graft copolymer and blend based on chitosan andN-isopropylacrylamide

Kim¹,

Cho²,

Lee³

et al. 2000

J. Appl. Polym. Sci.

199

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Thermo‐ and pH‐sensitive polymers were prepared by graft polymerization or blending of chitosan and poly(N‐isopropylacrylamide) (PNIPAAm). The graft copolymer and blend were characterized by Fourier transform‐infrared, thermogravimetric analysis, X‐ray diffraction measurements, and solubility test. The maximum grafting (%) of chitosan‐g‐(N‐isopropylacrylamide) (NIPAAm) was obtained at the 0.5 M NIPAAm monomer concentration, 2 × 10−3 M of ceric ammonium nitrate initiator and 2 h of reaction time at 25°C. The percentage of grafting (%) and the efficiency of grafting (%) gradually increased with the concentration of NIPAAm up to 0.5 M, and then decreased at above 0.5 M NIPAAm concentration due to the increase in the homopolymerization of NIPAAm. Both crosslinked chitosan‐g‐NIPAAm and chitosan/PNIPAAm blend reached an equilibrium state within 30 min. The equilibrium water content of all IPN samples dropped sharply at pH > 6 and temperature > 30°C. In the buffer solutions of various pH and temperature, the chitosan/PNIPAAm blend IPN has a somewhat higher swelling than that of the chitosan‐g‐NIPAAm IPN. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1381–1391, 2000

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Section: Resultsmentioning

confidence: 99%

Thermo- and pH-responsive behaviors of graft copolymer and blend based on chitosan andN-isopropylacrylamide

Kim¹,

Cho²,

Lee³

et al. 2000

J. Appl. Polym. Sci.

199

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“…It has been demonstrated that Ce(IV) complexes with diols, cleaving the carbon−carbon bond between the hydroxyls in polysaccharides to yield an aldehyde or ketone and a free radical (Scheme ). − Ce(IV) mainly creates radical sites on oligosaccharides . The hemiacetal group at the reducing end of a cellulosic chain has been shown to be much more reactive toward Ce(IV) than the midchain glycol groups. − It is therefore likely that a radical is relatively easily created at the reducing end of most of the oligosaccharide chains.…”

Section: Resultsmentioning

confidence: 99%

“…[38][39][40] Ce(IV) mainly creates radical sites on oligosaccharides. 41 The hemiacetal group at the reducing end of a cellulosic chain has been shown to be much more reactive toward Ce(IV) than the midchain glycol groups. [42][43][44] It is therefore likely that a radical is relatively easily created at the reducing end of most of the oligosaccharide chains.…”

Section: Debranched Starchmentioning

confidence: 99%

Grafting of Oligosaccharides onto Synthetic Polymer Colloids

et al. 2007

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A new method to form colloidally stable oligosaccharide-grafted synthetic polymer particles has been developed. The oligosaccharides, of weight-average degree of polymerization approximately 38, were obtained by enzymatic debranching of amylopectin. Through the use of a cerium(IV)-based redox initiation process, oligosaccharide chains are grafted onto a synthetic polymer colloid comprising electrostatically stabilized poly(methyl methacrylate) or polystyrene latex particles swollen with methyl methacrylate monomer. Ce(IV) creates a radical species on these oligosaccharides, which then propagates, initially with aqueous-phase monomer, then with the methyl methacrylate monomer inside the particles. Ultracentrifugation, NMR, and total starch analyses together prove that the grafting process has occurred, with at least 7.7 wt % starch grafted and a grafting efficiency of 33%. The surfactant used in latex preparation was removed by dialysis, resulting in particles colloidally stabilized with only linear starch as a steric stabilizer. The debranched starch that comprises these oligosaccharides is found to be a remarkably effective colloidal stabilizer, albeit at low electrolyte concentration, stabilizing particles with very sparse surface coverage.

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“…Still, a major disadvantage of the CAN system is that it needs strong acidic conditions that can degrade the starch backbone [ 10 ]. Also, the complex formation with starch is a slow process [ 4 , 16 ]. There is some evidence that the promise of high selectivity is not always obtained [ 16 , 17 ].…”

Section: Factors That Influence the Graft Selectivitymentioning

confidence: 99%

Grafting Starch with Acrylic Acid and Fenton’s Initiator: The Selectivity Challenge

Noordergraaf,

Witono,

Heeres

2024

Polymers

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Through the graft polymerization of acrylic monomers onto starch, materials with interesting new properties can be synthesized. Fenton’s chemistry, Fe2+/H2O2, is considered to be attractive for the initiation of graft polymerization with the monomer acrylic acid since it is cheap and reacts quickly at ambient conditions and should therefore be easy to scale up. However, the selectivity of the grafting versus the homopolymerization reaction poses a challenge with this monomer and this type of initiator. In the present review paper, we investigate why data from the literature on grafting systems with other monomers and initiation systems tend to show higher graft selectivity. A scheme is presented, based on reaction engineering principles, that supports an explanation for these observed differences. It is found that more selective activation of starch is a factor, but perhaps even more important is a low monomer-to-starch ratio at the starting sites of graft reactions. Since water is the most common solvent, monomers that are less water-soluble have an advantage in this respect. Based on the proposed scheme, methods to improve the graft selectivity with Fenton’s initiator and acrylic acid are evaluated. Most promising appears to be a method of gradual monomer dosage. With gelatinized cassava starch in a batch reactor, both the grafting percentage (17 => 29%) and graft selectivity (18 => 31%) could be improved. This can be considered a principal breakthrough. Still, more research and development would be needed to refine the method and to implement the idea in a continuous reactor at a larger scale.

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An approach to the knowledge of the graft polymerization of acrylic monomers onto polysaccharides using Ce(IV) as initiator

Cited by 17 publications

References 0 publications

Thermo- and pH-responsive behaviors of graft copolymer and blend based on chitosan andN-isopropylacrylamide

Thermo- and pH-responsive behaviors of graft copolymer and blend based on chitosan andN-isopropylacrylamide

Grafting of Oligosaccharides onto Synthetic Polymer Colloids

Grafting Starch with Acrylic Acid and Fenton’s Initiator: The Selectivity Challenge

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