Hydroxyl-Containing Polymers Having Aminimide Groups Attached Thereto Through an Ether Linkage

Hydroxyl-containing polymers such as polyvinyl alcohol and cellulose that have been alkylated to form ethers, for example such as cellulosic ethers, are well known to the art and possess wide utility. Hydroxyalkyl and carboxyalkyl derivatives are two particular classes of such substituted cellulosic products. The type of substituting groups, number of such groups per anhydroglucose unit and the method of preparing such substituted products provides a wide range of physical and chemical properties.

A novel process has now been found for preparing a new class of substituted polymers containing a plurality of hydroxyl groups having aminimide groups attached through either linkages as well as a new class of cross-linked film-forming materials.

The present invention is directed to novel polymers containing a plurality of hydroxyl groups having aminimide groups attached thereto. The present invention is also directed to methods for preparing such polymers.

FIG. 1 is an infrared spectrograph of hydroxypropyl cellulose;

FIG. 2 is an infrared spectrograph of an aminimidesubstituted hydroxypropyl cellulose polymer within the scope of the present invention;

FIGS. 3 and 4 are infrared spectrographs of a less soluble and a more soluble fraction, respectively, of the polymer represented in FIG. 2;

FIG. 5 is a thermogravametric analysis trace of an aminimide-substituted polymer within the scope of the present invention; and

FIG. 6 is a thermogravametric analysis trace of another aminimide-substituted polymer within the scope of the present invention.

The novel compounds of the present invention comprise aminimide-substituted derivatives of polymers containing a plurality of hydroxyl groups and are prepared by reacting said polymers with a compound of the formula: ##STR1## wherein each R.sub.1, R.sub.2 and R.sub.3 are alkyl groups; X is chloro, iodo or bromo; and each R.sub.4 and R.sub.5 are hydrogen, lower alkyl and phenyl. The aminimide group ##STR2## is preferably introduced into the hydroxyl-containing polymer by alkylation with tertiary amine .alpha.-halocarboximides of one or more of the hydroxyl groups to form ether linkages. It should be understood that all of the hydroxyl groups on the hydroxyl-containing polymer are available for the reaction. For example, in a preferred embodiment, wherein the hydroxylcontaining polymer is a cellulosic product, the hydroxyl group or groups at which the reaction takes place may be the hydroxyl group on the anhydraglucose unit and/or the hydroxyl of a substituent such as an hydroxyalkyl group.

As examples of hydroxyl-containing polymers contemplated by the present invention, mention may be made of the following:

cellulose

carboxymethyl cellulose

hydroxyethyl cellulose

methylcellulose

hydroxypropyl cellulose

ethyl cellulose

methyl hydroxyethyl cellulose

carboxymethyl hydroxyethyl cellulose

hydroxypropylmethyl cellulose

alginic acid

cellulose sulfate

kappacarrageenan

lambda carrageenan

soluble starch

gelatin

polyvinyl alcohol

It should also be understood that the term "polymers containing a plurality of hydroxyl groups" and "hydroxyl-containing polymers" include both homopolymers and copolymers as well as mixtures of such polymers.

Representative novel aminimide-substituted polymers within the scope of the present invention include the following: ##STR3##

Compound A is based on cellulose as a starting material, compounds B and C on hydroxyethylcellulose and compound D on hydroxypropyl cellulose. Compound E is based on polyvinyl alcohol.

It should be understood that in the case of the cellulosics, the location of the hydroxyalkyl groups and the aminimide groups are representative, since, as it is known in the art, the hydroxyalkyl groups may be introduced into the cellulose molecule in two ways: one; at the hydroxyls of the cellulose chain or two; at hydroxyls of substituents of previously substituted hydroxyls to form a side chain. In addition, theoretically, all hydroxyl positions can be substituted. Similarly, the aminimide group may be introduced into one or more of the hydroxyls of the cellulose molecule or the hydroxyls of the hydroxyalkyl groups.

The novel process of the present invention comprises the steps of swelling the polyhydroxyl-containing polymer in an organic solvent containing base and adding the above-described haloacetimide. It should be understood that the term "organic solvent" includes combinations of organic solvents as well as single organic solvents which will both swell the cellulosic starting material and dissolve the haloacetimide.

The haloacetimides employed in the present invention are set forth in greater detail in application Ser. No. 602,600 filed concurrently herewith, and which is incorporated herein by reference.

The following non-limiting examples illustrate the preparation of the novel compounds of the present invention.

In a flask fitted with a stirrer, nitrogen inlet, condenser and drying tube, potassium t-butoxide is prepared by dissolving 0.468g of potassium in 20 ml. of t-butanol. After the evolution of hydrogen has subsided, the solution is covered with a blanket of nitrogen and 1,344g of hydroxypropyl cellulose (sold by Hercules, Inc., Wilmington, Delaware under the trade name KLUCEL J) and 20 ml. of dimethylformamide is added. The mixture was allowed to steep for one hour at room temperature. A solution of 1.8g of trimethylamine .alpha.-chloroacetimide ##STR4## in 20ml. of t-butanol was then added and the mixture stirred at room temperature for 20 hours. The polymer was isolated by precipitation into hexane containing acetic acid and dried under vacuum. The polymer was redissolved in water and dialyzed in a cellophane membrane for 120 hours and then isolated by freeze drying. Proof of aminimide substitution was obtained by infrared spectra.

To further characterize the aminimide substituted products, the dialyzed material (without the freeze-drying step) was heated on a steam cone. A polymer fraction which will be designated A precipitated, was separated and analyzed. The supernatant was retained and designated B. Fraction A represented a cellulosic polymer having a low degree of aminimide substitution and, therefore, the less-soluble fraction. Fractions A and B were freeze-dried and subjected to nitrogen analysis and thermogravimetric analysis. Fraction A was found to contain 1.4% nitrogen and showed a 2.3% weight loss attributed to the elimination of trimethylamine.

Fraction B, which by its solubility indicated a higher degree of aminimide substitution, was also subjected to nitrogen analysis and thermogravimetric analysis. The polymer fraction was found to contain 7% nitrogen and a weight loss attributed to the elimination of trimethylamine of 14.5%. The analyses correspond to a degree of substitution of 1.

Turning now to the figures, FIG. 1 is an infrared spectrograph of the hydroxypropyl cellulose employed in Example 1. FIG. 2 is a spectrograph of the product of Example 1 after dialysis, while FIGS. 3 and 4 are spectrographs of Fractions A and B, respectively. The band at 1595 CM.sup.-.sup.1 represents the aminimide groups substituted on the hydroxypropyl cellulose.

FIG. 5 is a thermogravimetric trace of polymer Fraction B. The polymer was heated to dry the polymer and then the scale readjusted to 100% initial weight. Heating was then continued at a rate of 10.degree. C per minute until 170.degree. C was reached. The temperature was held at 170.degree. C until deamination ceased. The weight loss due to trimethylamine amounted to 14.5%.

FIG. 6 is a thermogravimetric trace of polymer Fraction A. The polymer was dried as with Fraction B. However, since the weight loss due to deamination was so relatively small, the scale was readjusted as indicated at the top of the figure. Weight loss due to trimethylamine amounted to 2.3%.

The aminimide-substituted polymers of the present invention can also be employed to form cross-linked films. Referring to the above-indicated thermogravimetric techniques, it is believed that the amine elimination results in the formation of isocyanate groups which in turn react with an available hydroxyl group to form a urethane. The above described reaction is believed to occur as follows: ##STR5##

What is believed to have occurred when the polymer of Example 1 was heated is illustrated below: ##STR6##

It should be understood, however, that the urethane linkage formed would not only be in that position. As with the aminimide substitution, any hdyroxyl group would be available for the reaction, either on another anhydroglucose unit or even on the same anhydroglucose unit.

The novel polymers of the present invention find utility in a variety of products. For example, the polymers are particularly suitable for uses as the viscosity increasing component of photographic processing compositions .