Latexes of starch-based graft polymers containing polymerized acrylonitrile

Abstract

SynopsisThe scope of graft reactions to produce starch-based latexes was extended by graft polymerization of acrylonitrile (AN) onto gelatinized cationic starch possessing quaternary amine functionality and by graft terpolymerization of AN and t-butylaminoethyl methacrylate (TBAEM) onto gelatinized starch by cerium(1V) initiation a t 25OC. Grafting onto starches containing highly basic quaternary amines gave polyacrylonitrile [poly(AN)] grafts having about one fourth the number-average molecular weight (Hn) (178,000-232,000) of those produced by grafting AN onto starches containing the less basic tertiary m i n e groups. Sonification a t 20 KHz of graft polymerization reaction mixtures having up to 8% solids reduced viscosities from 400-3000 cP to 10-40 cP. Diameters of dried particles measured about 300-1500 A. Shaker-type agitation during grafting onto starch having quaternary amine groups produced poly(AN) chains with lower A?,, values than those produced during blade stirrer-type agitation. M,, values of grafted poly(AN) decreased with increasing reaction time, degree of substitution of amine in the starch, gelation time of cationic starch a t 95OC, and cerium(1V) concentration. AN was copolymerized with TBAEM at molar ratios of 14-85:l in grafting onto gelatinized starch to yield copolymer side-chain grafts analyzing 8-52:l of polymerized AN to TBAEM moieties.

Synthesis and characterization of synthetic polymer colloids colloidally stabilized by cationized starch oligomers

“…We also demonstrated a new method to accurately quantify the starch fragments grafted on the final latex. The 13 C solid-state NMR method developed in the present work is assumption free and overcomes the limitation of the classical enzymatic methods, which are affected by the presence of synthetic polymers and cationic substituents. 50,53,56 It takes advantage of the fact that the 13 C CP-MAS spectrum of the final latex exhibits resolved signals for the individual components, and can easily be calibrated using a model blend of the individual components.…”

“…The final latex obtained by the ab initio synthetic pathway involving PNIPAM (Scheme 2, bottom) was used for method development. 13 C SPE-MAS and CP-MAS spectra of the final dialyzed and ultracentrifuged latex are shown in Figure 2 exhibits a higher signal-to-noise ratio than that of the SPE-MAS one. In particular, SPE-MAS does not detect the Amylofax and PNIPAM signals between 70 and 120 ppm in 15 h, while CP-MAS detects them with a high signal-to-noise ratio in 9 h. Therefore, CP-MAS was chosen to quantify the amount of Amylofax actually present in the centrifugate.…”

“…As the NMRactive 13 C nuclei represent only 1% of the C nuclei in natural abundance, SPE-MAS is usually not very sensitive, and requires long acquisition times. CP-MAS comprises irradiating the 1 H nuclei in the sample with a radiofrequency pulse, then transferring the magnetization from 1 H to 13 C nuclei, and then recording the 13 C signal. As 99.99% of the H nuclei are the NMR-active 1 H, CP-MAS is usually more sensitive than SPE-MAS for rigid samples, for which the CP magnetization transfer from 1 H to 13 C nuclei is efficient.…”

“…8 The use of a cationized starch rather than a native neutral one is expected to lead to species with enhanced colloidal stability, by combination of the cationic charge and stericstabilizing effects of the grafted starch, resulting in an electrosteric stabilizer. 10,11 Latexes stabilized with fragments of cationized starch have previously been synthesized by Gugliemelli et al After gelatinizing the cationized starch to disperse it (i.e., heating in water to break up the crystalline fractions of the starch), they grafted synthetic polymers onto the starch using cerium(IV) as an initiator for the polymerization of acrylonitrile 9,12,13 or chloroprene; 14 the mixture was finally sonicated to obtain a latex. The grafting step presumably led to a structure composed of a branched polysaccharide scaffold decorated with synthetic polymer particles.…”

Modification of starch by graft copolymerization

“…Poly(acrylic acid) and polychloroprene were grafted , respectively, on native and on cationic starch. The use of cationic starch led to latexes having strong cationic character which act as additives in wet‐end addition in paper manufacturing.…”