ISSN 1070-4272, Russian Journal of Applied Chemistry, 2014, Vol. 87, No. 10, pp. 1558−1565. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © N.K. Luneva, T.I. Ezovitova, 2014, published in Zhurnal Prikladnoi Khimii, 2014, Vol. 87, No. 10, pp. 1512−1521.
AND POLYMERIC MATERIALS
Cellulose Phosphorylation with a Mixture
of Orthophosphoric Acid and Ammonium Polyphosphate
in Urea Medium
N. K. Luneva and T. I. Ezovitova
Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus,
ul. Surganova 9/1, Minsk, 220072 Belarus
Received April 14, 2014
Abstract—Cellulose samples with various extents of structural ordering (native cotton cellulose and mercerized
cellulose) were phosphorylated with a mixture of orthophosphoric acid and ammonium polyphosphate in a urea
medium. The phosphorus content and ion-exchange capacity of phosphorylated mercerized cellulose are higher
than those of the initial natural polysaccharide phosphorylated under the same conditions. Modiﬁ cation of the
glucopyranose rings of cellulose mainly occurs in amorphous regions of the polymer. The maximal rate of thermal
degradation of cellulose phosphates is considerably lower than that of the initial polymers, and the degradation
rate maximum is observed at 238–245°С, in contrast to the main process of dehydration and carbonization of the
initial materials, occurring at 330–340°С. The results obtained can be used for preparing ion-exchange sorbents
and ﬁ reproof fabrics with preset properties.
Numerous studies deal with cellulose phosphorylation
[1–4]. As a rule, these papers and especially patents
concern imparting new properties to cellulose materials
by their esterification with phosphorus-containing
agents [5–7]. Researchers’ attention to synthesis of
phosphorus-containing materials is associated with the
fact that phosphorylation of polymers imparts to them
ion-exchange capacity, selectivity in uptake of Fe
, and Cu
ions, capability for sorption of proteins
and vitamins [8–11], and high ﬂ ame resistance [12, 13].
Cellulose phosphates in the form of fabric exhibiting
ion-exchange and ﬁ reprooﬁ ng properties are not yet
commercially produced in Belarus and CIS countries,
because modiﬁ cation by traditional procedures results
in 30–40% loss of the mechanical strength of the fabric,
making impossible its proper use. Preparation of cellulose
phosphates is still a subject of researchers’ interest.
Studies concerning the inﬂ uence exerted on the properties
of the products by their composition, phosphorylation
conditions, and composition of the phosphorylation
medium are being continued, and efforts are made to
develop new effective phosphorus-containing modiﬁ ers
imparting new properties to cellulose phosphates [14, 15].
Phosphorylation of cellulose in a melt of urea and
orthophosphoric acid (pH 1.3) was studied previously.
The possibility of formation of polyphosphoric acid
residues in ester groups was revealed. However, the
procedure is labor-consuming, costly, and unacceptable
for preparing phosphates, though it yields phosphates
with increased phosphorus content .
Another procedure for preparing cellulose phosphates
is modiﬁ cation of the polymer with an esterifying agent
consisting of aqueous orthophosphoric acid, urea, and
sodium tripolyphosphate . In this case, the esterifying
agent has pH 2.3, and its use for the polymer modiﬁ cation
results in formation of the phosphates exhibiting, along
with increased phosphorus content, also higher strength
(the loss is as low as 10–12%). However, the fabrics
prepared using sodium tripolyphosphate as a component
of the modiﬁ er in some cases did not exhibit the level