Transamidated poly-2-oxazoline compositions useful as wetting agents for polymer and absorbents for polar materials

A polymeric composition comprising a poly-2-oxazoline reacted by transamidation with a carboxylic acid, anhydride, salts of a carboxylic acid or combination thereof which can be blended with another polymeric composition to form a water wettable blend. In another aspect, the poly-2-oxazoline is crosslinked with a polybasic carboxylic acid by transamidation. The crosslinked polymeric composition is useful as an absorbent for polar materials.

BACKGROUND OF THE INVENTION 
This invention relates to polymeric compositions derived from the 
transamidation of poly-2-oxazoline with carboxylic acids. Optionally, 
anhydrides or salts of carboxylic acids can be employed as substitutes or 
in conjunction with the carboxylic acids. These compositions have an 
affinity for polar materials and, therefore, are useful in areas requiring 
this characteristic. 
The strong tendency of the subject polymeric compositions to absorb or bind 
polar materials means they can be compounded with normally nonwettable 
polymers to make them water wettable. Further, the subject polymers can be 
made insoluble by crosslinking and, therefore, can be employed as an 
absorbent for polar materials. 
SUMMARY OF THE INVENTION 
The present invention is a polymeric composition comprising (a) a polymer 
of poly-2-oxazoline and (b) a carboxylic acid, anhydride, salt of a 
carboxylic acid or combination thereof where the (b) component has reacted 
by transamidation with the poly-2-oxazoline. In a preferred embodiment, 
the polymeric composition is poly-2-ethyloxazoline and a carboxylic acid. 
The subject polymeric composition can be blended with another polymeric 
composition to form a water wettable blend. 
In another aspect, the present invention is a polymeric composition 
comprising (a) a polymer of poly-2-oxazoline and (b) a polybasic 
carboxylic acid which has reacted by transamidation with the 
poly-2-oxazoline to crosslink the poly-2-oxazoline. Preferably, the 
crosslinked polymeric composition is poly-2-ethyloxazoline and 
ethyleneaminediaminetetraacetic acid. The subject crosslinked polymeric 
composition is useful as an absorbent for polar materials. In particular, 
the crosslinked polymeric composition swells into a gel-like mass in the 
presence of polar materials to entrap them. 
DETAILED DESCRIPTION OF THE INVENTION 
Generally, the polymeric composition of the subject invention entails the 
transamidation reaction of poly-2-oxazoline with carboxylic acid. The 
particular characteristics of the composition are dependent on the degree 
of conversion and carboxylic acid employed. Generally the transamidation 
reaction, Reaction A, involving poly-2-oxazoline with carboxylic acid can 
be structurally depicted as follows: 
##STR1## 
Reaction A depicts partial transamidation wherein a portion of the R.sub.1 
groups present on the poly-2-oxazoline have been replaced by the R.sub.2 
groups from the carboxylic acid. R.sub.1 is typically hydrogen, phenyl, or 
alkyl having up to 18 carbon atoms or an inertly-substituted derivative 
thereof. R.sub.2 is typically hydrogen, phenyl, or alkyl having up to 22 
carbon atoms or an inertly-substituted derivative thereof. Optionally a 
majority of the R.sub.1 groups present on the poly-2-oxazoline can be 
replaced by the R.sub.2 groups. The more preferred reaction involves the 
transamidation of poly-2-oxazoline with a polybasic carboxylic acid such 
as di-, tri- or tetracarboxylic acid. A reaction with the polybasic 
carboxylic acid provides the advantage of crosslinking the 
poly-2-oxazoline which in turn provides an insoluble characteristic to the 
polymeric composition. Coupled with the affinity of the polymeric 
composition for polar materials, the crosslinked composition will form a 
gel in the presence of polar materials to thus behave as an absorbant. The 
reaction of poly-2-oxazoline with polybasic carboxylic acids, Reaction B, 
can be structurally depicted as follows where "Z" represents 
##STR2## 
Reaction B indicates partial transamidation, x-2, where all the carboxyl 
groups, x, have not reacted. Optionally all the carboxyl groups present on 
the polybasic carboxylic acid can react. R.sub.1 is typically hydrogen, 
phenyl, or alkyl having up to 18 carbon atoms or an inertly-substituted 
derivative thereof. R.sub.2 is typically hydrogen, phenyl, or alkyl having 
up to 22 carbon atoms or an inertly-substituted derivative thereof. 
As can be seen from the Reactions A and B, the major components which make 
up the subject polymeric composition are poly-2-oxazoline and a carboxylic 
acid. However, it is understood that the poly-2-oxazoline need not be a 
homo-polymer but may be a portion of a copolymer. 
The other elements of the copolymer may comprise polyolefins, polyamines, 
and polyethers. Examples of such copolymers are 
poly[styrene-.beta.-methyloxazoline], S. L. N. Seung and R. N. Young, J. 
Polymer Sci., Polymer letters, 17, 233 (1979); 
poly[styreneoxide-.beta.-methyloxazoline], IBID, 18, 89 (1980); 
poly[isobutylene-.beta.-methyloxazoline], V. Percec et al., Polymer Bull., 
8, 25 (1982). 
The term poly-2-oxazoline as used herein is meant to define compounds of n 
randomly-joined units (I, II) and are readily prepared by the ring-opening 
polymerization of 2-oxazolines or like compounds (III). 
##STR3## 
The substituents and subscripts are hereinafter defined. The ring-opening 
polymerization of 2-oxazoline monomers is generally conducted in the 
presence of a cationic polymerization catalyst at a reaction temperature 
of about 0.degree. C.-200.degree. C. Typical catalysts include strong 
mineral acids, organic sulfonic acids and their esters, acidic salts such 
as ammonium sulfate, Lewis acids such as aluminum trichloride, tin 
tetrachloride, boron trifluoride and organic diazoniumfluoroborates, 
dialkyl sulfates and other like catalysts. This ring-opening 
polymerization is further described by Tomalia et al., J. Polymer Science, 
4, 2253 (1966); Bassiri et al., Polymer Letters, 5, 871 (1967); Seeliger, 
Ger. 1,206,585; Jones and Roth, U.S. Pat. No. 3,640,909; and Litt et al., 
U.S. Pat. No. 3,483,141. 
The pre-hydrolyzed polymers thereby obtained are linear, N-acylated 
polyethyleneimines or polytrimethyleneimines having a molecular structure 
consisting essentially of repeating units (I). These polymers can be used 
as such or the partially hydrolyzed form. These polymers are easily 
hydrolyzed (deacylated) by contact with a strong acid, such as HCl, 
followed by contact with a base, such as NaOH. This process is further 
described by K. M. Kem, J. Polymer Science, 17, 1977 (1979). The partially 
hydrolyzed polyoxazolines, have a molecular structure consisting 
essentially of the randomly-joined units (I) and (II), illustratively 
depicted as: 
##STR4## 
wherein: n is the total number of units or degree of polymerization; h is 
the number of acylated units; and n-h is the number of hydrolyzed units. 
In the present invention, n-h is within the range of from zero to about 50 
percent of n. In the above formulae, R is typically hydrogen or C.sub.1 
-C.sub.3 alkyl; R' is typically hydrogen, phenyl or an alkyl group having 
up to about 18 carbon atoms or an inertly-substituted derivative thereof; 
and x is 1 or 2. As used herein, "2-oxazoline" includes both 
poly-2-oxazoline monomers, i.e., x is 1 and 2-dihydrooxazine monomers, 
i.e., x is 2, and "poly-2-oxazoline" includes both poly-2-oxazoline 
polymers and poly-2-dihydrooxazine polymers. By such terms as 
"inertly-substituted" is meant that the substituents do not preclude the 
polymerization of the 2-oxazoline monomers. Illustrative inert 
substituents include halogen, alkenyl hydrocarbons, alkoxy, ester, etc. 
Exemplary R substituents include hydrogen, methyl, ethyl and proply and 
exemplary R' substituents include hydrogen, methyl, ethyl, propyl, pentyl, 
cyclohexyl, dodecyl, octadecyl, and the various halogenated, ethylenically 
unsaturated, etc., derivatives of each such as 
poly(2-trichloromethyl-2-oxazoline), poly(2-isopropenyl-2-oxazoline), etc. 
Typically, the poly-2-oxazoline has a molecular weight within the range of 
1,000 to 1,000,000. In the present invention, it is preferable to use a 
poly-2-oxazoline having a molecular weight within the range of about 
100,000 to about 600,000. 
With respect to the second major component of the subject transamidation 
reaction the term carboxylic acids is meant to define compounds 
represented by the formula R(COOH).sub.x where R is an alkyl, aryl, alkyl 
or aryl substituted group and x is 1 or more. Preferably x is 2 to 4, 
meaning polybasic carboxylic acids which are capable of crosslinking the 
poly-2-oxazoline. Examples of preferred carboxylic acids are stearic acid, 
benzoic acid, adipic acid, and ethylenediaminetetraacetic acid (EDTA). 
Optionally anhydrides and salts of carboxylic acids can be employed for or 
in conjunction with the carboxylic acids to perform the transamidation 
function. Just as with the carboxylic acids, multi-functional anhydrides 
and salts of carboxylic acids are preferred in order to crosslink the 
poly-2-oxazoline. Examples of anhydrides which can be employed are maleic 
anhydride, succinic anhydride, pathalic anhydride and the like. Salts of 
carboxylic acids can be any of those generally described under carboxylic 
acids. 
Generally the subject polymeric composition can be prepared by intimately 
blending the two components (poly-2-oxazoline and carboxylic acid, 
anhydride, or acid salt) such that transamidation occurs. This blending 
can be carried out by various means such as in a mixer, Brabender or on a 
mill. 
One means for identifying when the transamidation reaction has occurred 
such that the poly-2-oxazoline has become crosslinked is by monitoring the 
torque of the blending mechanism employed. Generally it has been found 
that there is an increase in torque as the transamidation reaction 
proceeds. 
The temperature at which the reaction process proceeds is not particularly 
critical so long as the stability limitations of the components are not 
exceeded; however, for ease of blending temperatures over 180.degree. C. 
are recommended. Preferably the process temperature is from 200.degree. C. 
to 250.degree. C. to blend the components in a time effective manner. 
Naturally it is understood that the time for blending is dependent on the 
volume of product to be prepared, the blending means employed and the 
particular temperature chosen. The end-point for reacting the components 
is identifiable by torque measurements as aforementioned. 
The subject polymeric composition comprises poly-2-oxazoline and sufficient 
carboxylic acid to transamidate and/or crosslink the poly-2-oxazoline to 
any desired degree. Generally, therefore, the polymeric composition of the 
invention comprises from about 70 to about 99 percent by weight 
poly-2-oxazoline, and from about 1 to about 30 percent by weight 
carboxylic acid. The preferred operative range is from about 90 to about 
97.5 percent by weight poly-2-oxazoline and from about 2.5 to about 10 
percent by weight carboxylic acid. It is understood the anhydrides, or 
salts of carboxylic acids as explained above can optionally be employed 
for or in conjunction with the carboxylic acid component. 
Applications for the polymeric composition are varied but are generally 
related to the affinity the compositions have for polar materials. For 
example, compositions prepared from poly-2-ethyloxazoline and adipic acid 
or zinc stearate have been found to be useful as wetting agents for 
polymers. What is meant by wetting agents for polymers is that 
non-wettable polymers such as polypropylene can be made water wettable by 
blending the subject composition into the polypropylene. Thus, the 
polymeric composition of the invention can be blended with a normally 
non-wettable polymer to form a water wettable blend. Water wettable is 
defined as the characteristic of having water droplets cling to the molded 
flat surface of the polymer without readily sliding off as the surface 
angle is changed. Furthermore, the reaction of carboxylic acids with the 
poly-2-oxazolines has been found to improve the compatibility of 
poly-2-oxazoline with other polymers such as polypropylene. This was 
demonstrated when unmodified poly-2-ethyloxazoline tended to become 
brittle and wash away from the surface of molded polypropylene. Meanwhile, 
70 percent poly-2-ethyloxazoline reacted with 30 percent stearic acid was 
found to be flexible with reduced water solubility. 
In another aspect the subject polymeric composition, when formed from 
multibasic carboxylic acids is an absorbent for polar materials by 
swelling into a gel-like mass in their presence. The gel characteristic 
indicates the presence of crosslinking. Preferably, the subject polymeric 
composition can absorb several times its weight of a polar liquid and more 
than 15 times its weight of water. The polymeric composition of the 
invention is therefore useful as an absorbent for organic materials. More 
particularly the polymeric composition can be employed to remove polar 
materials from nonpolar feedstreams such as in shut-off filters for fuels 
and hydraulic fluids. One method can comprise employing the subject 
polymeric composition in conjunction with a filter medium to separate 
water and polar organics from a non-polar hydrocarbon stream. In yet 
another aspect the subject polymeric composition can be dispersed in an 
absorbent medium, such as paper or other fibers, to assist in the 
absorbance of water or other polar material. 
The following examples are provided to illustrate the preparation of the 
subject polymeric composition.

EXAMPLE I 
A brabender mixer was heated to 225.degree. C. and 47.5 grams (g) of 
poly-2-ethyloxazoline (MW 200,000) (hereinafter referred to as PEOx) was 
added. After allowing the PEOx to mix for ten minutes 2.5 g of adipic acid 
was added. Initially there was a decrease in torque which indicated 
plasticization of the PEOx; however, after an additional twenty minutes 
mixing a rapid increase in torque was noted which indicated that the 
transamidation reaction had occurred. A further fifty minutes of mixing 
was completed and the product was removed and cooled. 
A 2 g sample of the product was added to 15 g of water in a closed bottle 
and placed on a bottle roller overnight. Upon inspection the sample had 
swelled into a gel-like mass. Portions of the gel were placed in 1N NaOH 
and 1N HCl solutions overnight and remained unchanged in appearance. This 
indicated that the PEOx was crosslinked by the adipic acid. 
EXAMPLE II 
A product consisting of 90 weight percent PEOx and 10 weight percent 
stearic acid was prepared in a mixer at 225.degree. C. by blending the 
components for fifty minutes. The product was collected, cooled and ground 
into fine particles. The fine particles were then melt blended into 
polypropylene at 200.degree. C. to form a modified polypropylene blend 
consisting of 10 weight percent PEOx/stearic acid product and 90 weight 
percent polypropylene (Hercules Profax.RTM. 6331). 
The modified polypropylene blend was finely ground and injection molded 
into a disc. The contact angle with water of the molded disc was then 
measured on a goniometer which showed the modified polypropylene blend to 
be water wettable. 
EXAMPLE III 
A modified polypropylene blend was prepared as in Example II except that 
zinc stearate was employed instead of stearic acid. The contact angle with 
water for the molded disc was measured with a goniometer and showed the 
modified polypropylene blend to be water wettable. 
EXAMPLE IV 
A brabender mixer was heated to 220.degree. C. and 45 g of PEOx was added. 
After five minutes 5 g of ethylenediaminetetraacetic acid (EDTA) was added 
to the PEOx. The mixture was blended at 50 rpm until the torque reached 
2500 g-cm. The blended polymeric composition was collected and allowed to 
cool. The resulting product was brittle at room temperature and was ground 
on a mill into a small particle size. 
To demonstrate the absorbent properties of the PEOx/EDTA product the ground 
product was placed in polar liquids and the grams of polar liquid absorbed 
per gram of PEOx/EDTA product was measured. The results showed that a 1 g 
sample of the PEOx/EDTA absorbed, individually, 26 g of methanol; 29 g of 
95% ethanol/5% water; 11 g of methylethylketone; 14 g of acetone; 36 g of 
deionizer water; 31 g of a 1% NaCl solution; 3 g of toluene; and 28 g of a 
1N H.sub.2 SO.sub.4 solution. 
In view of the foregoing, the subject product can be advantageously 
employed in filter mediums used in non-polar hydrocarbon feed streams. In 
particular a polymeric composition such as PEOx/EDTA may be dispersed in a 
fiberglass filter medium as is generally described in U.S. Pat. No. 
4,242,286 which discloses a filter mechanism construction.