An acrylamide co-polymer which contains from between 1-60 mole percent of (2-acrylamido-2-hydroxy ethyl) trialkyl ammonium salt groups. These co-polymers are made by reacting (formylmethyl) trialykl ammonium salts at a pH of at least 9 and a temperature of between 15-80 degrees centigrade.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to cationic acrylamide co-polymers, in particular, 
acrylamide co-polymers functionalized by formocholine iodide (FCI) and 
their method of manufacturer. 
2. Description of the Prior Art 
Cationic acrylamide polymers are used for a variety of industrial 
applications. These water soluble co-polymers find usefulness as 
flocculants, coagulants and as dispersants. There are a number of cationic 
acrylamide polymers which are prepared by a variety of synthetic 
techniques. The present invention provides a series of novel cationic 
acrylamide polymers which are readily prepared from simple starting 
materials using relatively simple reaction conditions. 
The basis of the synthetic technique to prepare the novel cationic 
acrylamide polymers of the invention stems from the known reaction of 
aldehyde containing compounds with primary amides, which yields secondary 
amide products. For example, carboxylic acid functionality may be grafted 
onto a polyacrylamide backbone by reacting the polyacrylamide with 
glyoxylic acid. 
SUMMARY OF THE INVENTION 
An acrylamide co-polymer which contains from between 1-60 mole percent of a 
(2-acrylamido-2-hydroxy ethyl) lower trialkyl ammonium salt. The invention 
also relates to the method of producing these co-polymers which comprises 
reacting an aqueous solution of polyacrylamide with a (formylmethyl) lower 
trialkyl ammonium salt at a pH of at least 9 and at a temperature between 
15-80 degrees C. for a period of time sufficient to produce the 
co-polymer. 
In a preferred embodiment of the invention, the alkyl groups are methyl 
groups. The anion may be chloride, bromide, iodide or methyl sulfate.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The Starting Acrylamide Polymers 
Polyacrylamides having molecular weights as little as 1,000 up to as much 
as several million are readily modified using the techniques more 
specifically described hereafter. Typically, the acrylamide polymers 
modified in accordance with the invention would have molecular weights 
preferably in the range of about 5,000 to about 20,000,000. In the 
examples hereafter set forth the acrylamide polymers that have been 
modified have molecular weights of 10,000 and over 1,000,000. The 
molecular weights described above are weight average molecular weights. 
The Cationic Modifying Agent 
The cationic modification agents used to produce cationic co-polymers of 
the invention are the (formylmethyl) trialkyl ammonium salts. In a 
preferred embodiment of the invention, alkyl groups are methyl. 
MOLE RATIO OF THE (FORMYLMETHYL) TRIALKYL AMMONIUM SALT COMPOUND TO THE 
STARTING ACRYLAMIDE POLYMER 
This cationic modifying agent is capable of reacting with the 
polyacrylamides to produce substituted acrylamide co-polymers which 
contain between 1-60 mole percent of (2-acrylamido-2-hydroxy ethyl) 
trialkyl ammonium salt polymers. In most instances the molar percent of 
the cationic acrylamide substituent will range between about 3 to 50 mole 
percent. The amount of cationic charge imparted to the acrylamide may be 
varied over a wide range employing a variety of starting acrylamide 
polymers having various molecular weights. This allows the production of 
cationic polymers that can be tailored to a specific industrial 
application, such as dispersion, flocculation and the like. 
Preparation of the Modified Acrylamide Polymers of the Invention 
To simplify understanding of the preparative techniques described hereafter 
the following glossary is presented: 
______________________________________ 
Glossary 
______________________________________ 
DMDMEA 2,2-Dimethoxy-N,N-dimethylethylamine 
DMETMAI 2,2-Dimethoxyethyl trimethyl ammonium iodide 
FCI Formocholine iodide or (formylmethyl) 
trimethyl ammonium iodide 
NMR Nuclear mgnetic resonance 
polyacrylamido 
Acrylamide/2-acrylamido-2-hydroxyethyl 
quat trimethyl ammonium iodide copolymer 
ppm Parts per million 
PVSK Poly(vinylsulfuric acid) potassium salt 
______________________________________ 
EXAMPLES 
Synthesis of the (Formylmethyl) Dimethyl C.sub.1 -C.sub.4 Alkyl Ammonium 
Salt Compound 
The (formylmethyl) dimethyl C.sub.1 -C.sub.4 alkyl ammonium salt compound 
is synthesized by reacting a primary halide of up to four carbons in 
length with 2,2-dimethoxy-N,N-dimethyl ethylamine in methanol to yield a 
quaternary ammonium acetal. The acetal is then hydrolyzed to an aldehyde 
by treatment with acid. The scheme is demonstrated by the synthesis of 
FCI, but the substitution of methyl iodide with other short chain alkyl 
halides will produce other cationic modifying agents. The FCI is a stable 
compound, although in an aqueous environment it undergoes a reversible 
reaction with water to yield 2,2-dihydroxyethyl trimethyl ammonium iodide, 
which will be referred to as the hydrated form of FCI. FCI and the 
hydrated form of FCI are considered to be the same compound. Degradation 
of FCI occurs at a pH of 13 or greater in an aqueous environment and at 
lower pH when dissolved in an aprotic solvent. 
Synthesis of DMETMAI 
Into a reactor fitted with standard equipment was charged 20.0 g (0.15 
moles) of DMDMEA and 40 ml of methanol. The mixture was cooled and 29.0 g 
(0.20 moles) of methyl iodide was slowly added. When the addition was 
complete, the mixture was refluxed for several hours. Upon cooling in a 
dry ice/acetone bath, an amber colored solid precipitated. The solid was 
isolated by filtration and dried at room temperature. DMETMAI was 
characterized by proton and carbon NMR. Proton NMR signals were detected 
at 3.45 (singlet), 3.67 (singlet), 3.73 (doublet), and 5.10 (triplet) ppm. 
Carbon NMR signals were detected at 54.7, 55.2, 65.4 and 98.9 ppm. 
Synthesis of FCI 
Into a reactor fitted with standard equipment was charged 35.94 g (0.27 
moles) of DMETMAI and 50 ml of deionized water. The pH of the mixture was 
adjusted to 1.0 by the addition of 0.84 g of 10M HCl. The mixture was 
stirred and heated at about 99.degree. C. for 18 hours. A Dean-Stark trap 
was added to the reactor assembly and the mixture was heated to 
110.degree. C. to remove solvent. FCI was used as an aqueous solution. FCI 
was characterized by carbon NMR. Carbon NMR signals were detected at 55.0, 
69.0 and 85.4 ppm. 
Synthesis of Low Molecular Weight Polyacrylamido Quat 
Into a vial was added 21.04 g of a 35% aqueous solution of polyacrylamide 
(10,000 M.W.), 13.76 g of a 40% aqueous solution of FCI and 0.05 g of 
deionized water. The mixture was stirred and adjusted to a pH of 9.0 with 
0.55 g of a 50% aqueous solution of NaOH. The mixture was allowed to react 
without heating. The polyacrylamido quat was characterized by carbon NMR. 
In addition to signals typically detected for polyacrylamide, carbon NMR 
signals at 54.8, 67.8, 69.6 and 176.3 ppm were detected. 
Synthesis of High Molecular Weight Polyacrylamido Quat 
Into a reactor fitted with standard equipment was charged 25.5 g of a 30.5% 
polyacrylamide latex. In a beaker, 13.3 g of a 61.3% aqueous solution of 
FCI was stirred and adjusted to a pH of about 9 with a 50% aqueous 
solution of NaOH. The basic FCI solution was added to the reactor 
containing the polyacrylamide latex. The mixture was stirred and an 
additional 50% aqueous NaOH was added to obtain a reaction mixture pH of 
9.0. After sixteen hours of stirring, the reaction mixture was added to 
methanol acidified with HCl. The functionalized polymer precipitated upon 
addition of the methanol and additional aqueous HCl was added to obtain a 
pH of 4.0. The polyacrylamido quat was isolated by filtration and 
characterized by carbon NMR. Carbon NMR spectra similar to the carbon 
spectra from the low molecular weight polyacrylamido quat were obtained. 
THE POLYACRYLAMIDO QUAT 
The reaction of FCI and polyacrylamide that yields the polyacrylamido quat 
is a relatively slow reversible reaction. Carbon NMR analysis indicates 
that at 25.degree. C. and a pH of 9.0 the reaction will produce an 
equilibrium condition in about sixteen hours. At this time, both 
functionalized polyacrylamide and unreacted FCI will be present. The 
extent and rate of reaction will be influenced by pH, temperature and 
concentration. 
Effect of Concentration on the Acrylamide/FCI Reaction 
The concentration stability issue was approached by varying the water 
content of three polyacrylamide and FCI solutions. A mixture of a 30% 
aqueous solution of polyacrylamide and FCI was prepared. The 
polyacrylamide and FCI were in a 20:1 mole ratio of polyacrylamide to FCI. 
The pH of the mixture was adjusted to 9.0 with NaOH. Water was then added 
to the mixture to bring the non-volatile content of 30%. Two aliquots of 
this sample were further diluted to produce mixtures having non-volatile 
contents of about 20% and 10%. The samples were allowed to stand for 
several days before analysis by carbon NMR. The results are listed in 
Table IV. 
TABLE IV 
______________________________________ 
Percent Reacted FCI as a Function of Concentration at a 
Polyacrylamide/FCI Mole Ratio of 20:1, 
pH 9 and Temperature of 22.degree. C. 
Concentration % Polyacrylamido 
(Wt. %) % Reacted FCI 
Quat 
______________________________________ 
30 75 4.0 
20 64 3.5 
10 46 3.5 
______________________________________ 
Analysis of the data in Table IV indicates that less polyacrylamido quat 
forms at lower concentrations, hence the desirability of using 
concentrated polyacrylamide solutions for the reactions. To demonstrate 
the reversibility of the polyacrylamide/FCI reaction, three samples were 
prepared in a manner similar to that described above but with two major 
differences. First, the polyacrylamide to FCI mole ration was about 4:1. 
Secondly, the initial solution was allowed to stand for several days 
before the dilutions were made. This permitted the maximum amount of 
polyacrylamido quat to form prior to analysis. 
The analysis of these samples is listed in Table V. The extent of FCI 
reaction for these samples is proportional to the degree to which the 
system is in equilibrium, since the diluted samples would have an extent 
of reaction similar to that of the most concentrated sample prior to 
dilution. Comparison of the extent of reaction data of Tables IV and V 
indicates that the percentage of FCI that reacts is independent of the 
polyacrylamide to FCI mole ratio. 
TABLE V 
______________________________________ 
Percent Reacted FCI as a Function of Concentration at a 
Polyacrylamide/FCI Mole Ratio of 4:1, 
pH 9 and Temperature of 22.degree. C. 
Concentration % Polyacrylamido 
(Wt. %) % Reacted FCI 
Quat 
______________________________________ 
30 75 16.0 
20 64 13.5 
10 51 11.0 
______________________________________ 
Effects of Temperature on the Polyacrylamide/FCI Reaction 
A sample composed of FCI and polyacrylamide in a 1:4 mole ratio of FCI to 
polyacrylamide was prepared at a pH of 9.0. The sample had a non-volatile 
content of 30%. The sample was split in three portions. One portion was 
stored at room temperature, another was stored at 40.degree. C. and the 
third at 60.degree. C. After approximately 100 hours in storage, the 
samples were analyzed by carbon NMR at the temperatures that each sample 
was stored to obtain accurate product distributions. The NMR results are 
listed in Table VI. The data indicates that elevated temperatures reduce 
the amount of polyacrylamido quat formed in the equilibrium reaction. 
TABLE VI 
______________________________________ 
Percent Reacted FCI as a Function of Temperature at a 
Polyacrylamide/FCI Mole Ratio of 4:1, 
pH 9 and Concentration of 30% (Wt.) 
Temperature (.degree.C.) 
% Reacted FCI 
______________________________________ 
22 75 
40 72 
60 69 
______________________________________ 
Effect of pH on the Polyacrylamide/FCI Reaction 
The effect of pH on the polyacrylamide/FCI reaction was studied in three 
samples at pHs of 9.0, 6.0 and 3.0. The samples were composed of FCI and 
polyacrylamide in approximately a 1:4 mole ratio of FCI to polyacrylamide 
and had a non-volatile residue of about 30%. After mixing, the samples 
were allowed to stand for several days and were then analyzed using carbon 
NMR. The results are listed in Table VII. 
TABLE VII 
______________________________________ 
Percent Reacted FCI as a Function of pH at a 
Polyacrylamide/FCI Mole Ratio of 4:1, Concentration 
of 30% (Wt.) and Temperature of 22.degree. C. 
pH % Reacted FCI 
______________________________________ 
9 75 
6 &lt;5 
3 &lt;5 
______________________________________ 
Virtually no reaction of the FCI with polyacrylamide was observed at pH 3 
or 6. These results indicate the lower pH of the sample significantly 
slows the rate of the polyacrylamide/FCI reaction. As a result, it is 
possible to prepare a polyacrylamido quat using the disclosed method at a 
high pH and then stop the reaction indefinitely by lowering pH. This 
allows for ease of storage of the product. Once the stopped reaction 
mixture has been removed from storage, the polyacrylamide quat may be 
directly applied to a given process stream. 
Stabilization of the Polyacrylamido Quat 
It is clear from the above data that the polyacrylamide/FCI reaction is in 
equilibrium and conditions of high temperature and low concentration will 
result in polyacrylamido quat decomposition. The effect pH, on the other 
hand, can be used to stabilize the polyacrylamido quat. 
A 30% solution of polyacrylamide and FCI in a 4:1 mole ratio of 
polyacrylamide to FCI prepared at pH 9.0 and shown to contain a 
significant amount of polyacrylamido quat, was treated with HCl to lower 
the sample pH to about 4. The sample was than monitored by carbon NMR for 
a 16 hour period. No detectable change in the concentration of the 
polyacrylamido quat occurred, suggesting that the lowering of the pH 
dramatically effects the rate, not the equilibrium, of the reaction. 
To further test the stability of the polyacrylamido quat the low pH sample 
described above was diluted from 30% to about 15% with water. The diluted 
sample was then monitored by carbon NMR for a period of about 16 hours 
with no decomposition of the polyacrylamide quat observed. When a sample 
of polyacrylamido quat at pH 9 was diluted, decomposition of the 
polyacrylamido quat was observed. 
To provide a more rigorous test of the sample's concentration stability, 
the above described sample was diluted to a non-volatile content of 2% 
with water. The sample was analyzed by carbon NMR several days, and then 
several weeks, after dilution. The data indicates that 75% of the FCI is 
present as the polyacrylamido quat. By reducing the pH of the 
polyacrylamido quat, the rate of the equilibrium reaction is been slowed 
to the extent that the product can be considered stable. 
The above sample was then diluted and titrated with 0.001N PVSK to 
determine if the charge on the pH stabilized cationic polymer was 
detectable by wet chemical methodology. The 14 mole percent charge 
detected by colloid titration is in very good agreement with the 16 mole 
percent charge estimated from the NMR spectrum of the sample. 
Results of this work indicate that polyacrylamido quat is readily prepared 
from the room temperature reaction of polyacrylamide and FCI at pH 9. This 
is an equilibrium reaction which will reverse, if the product is diluted 
at high pH. The rate at which a new equilibrium is established is rather 
slow, suggesting that high pH use of the polyacrylamido quat may be 
possible, if the time frame for dilution and application does not allow 
significant change of the reaction equilibrium. However, at low pH the 
polyacrylamido quat has been shown to be concentration stable as a result 
of slowing of the forward and reverse reaction kinetics. 
The polymer is expected to lose its cationic charge gradually once it is 
discharged into the environment. The resulting uncharged polyacrylamide is 
much less toxic to aquatic life.