Process for catalytic preparation of poly(ether-amide) polymeric composition from oxazoline and polyphenol

A process comprising copolymerizing an oxazoline with a bis-or poly-phenolic compound in the presence of a catalyst which is a cationic complex of an alkali or an alkaline earth metal at a temperature in the range of from about 100.degree. to 200.degree. C. is described.

This invention relates to an improved process for the production of 
crosslinked polymeric compositions composed of repeating segmental 
residues having ether and amide linkages by the copolymerization of an 
oxazoline and a bis- or poly-phenolic compound in the presence of a 
catalyst which is a cationic complex of an alkali or alkaline earth metal. 
This invention is an improvement over the process described in U.S. Pat. 
No. 4,430,491. 
It is known that a 2-oxazoline will react with a compound containing an 
active hydrogen group of sufficient acid strength in a ring opening type 
mechanism to provide a secondary amide. Active hydrogen compounds reported 
in the prior art capable of undergoing the indicated reaction include 
carboxylic acids, thiols and phenols, the latter embracing the various 
phenol-aldehyde or phenol-ketone condensates containing a plurality of 
aromatic hydroxy groups. The reaction of a novalak in this manner to 
prepare a polyamine precursor is exemplified in U.S. Pat. No. 4,195,154. 
In accordance with this invention, an improved process for preparing 
polymeric compositions having segmental residues containing ether and 
amido linkages is provided. The improved process involves carrying out the 
polymerization reaction of a compound having a plurality of 2-oxazoline 
groups with a compound having a plurality of aromatic hydroxyl groups in 
the presence of a catalytic amount of a catalyst which comprises an alkali 
or alkaline earth metal complex. The underlying reaction mechanism is 
believed to be one wherein the active hydrogen atom of an aromatic 
hydroxyl group effects ring opening of the 2-oxazoline group resulting in 
the rearrangement thereof to form a secondary amide linkage. The reaction 
is believed to proceed progressively to provide the indicated alternating 
ether and amido linkages along the component polymeric chains. Use of the 
cationic catalyst is believed to result in simultaneous ring opening 
homopolymerization of oxazoline. Thermoplastic compositions are obtained 
when each of the respective reactants is difunctional in the absence of 
any catalyst. However, crosslinked or thermoset compositions, on the 
otherhand, are provided when either the functional groups of said 
respective reactants total at least five or a cationic catalyst is used. 
The oxazolines useful in the practice of this invention include a variety 
of such compounds having at least two 2-oxazoline groups per molecule. The 
applicable polyfunctional oxazolines are devoid of other functional groups 
capable of reacting in any manner with either an oxazoline group or an 
aromatic hydroxyl group. From the standpoint of potential commercial 
availability in commodity proportions the oxazolines derived from the 
polycarboxylic acids are preferred. Particularly examplary of such 
polyacids are the aromatic acids; e.g., isophthalic acids, terephthalic 
acid and trimesic acid. The indicated polyfunctional oxazoline compounds 
can be conveniently prepared by the reaction of the corresponding esters 
of said polyacids and ethanolamines. 
Representative polyfunctional oxazoline compounds useful in the process of 
this invention include the following bis-oxazolines: 
4,4', 5,5'-tetrahydro-2,2'bisoxazole; a 2,2'-(alkanediyl) bis 
(4,5-dihydrooxazole), e.g. 2,2'-(1,4-butanediyl) bis(4,5-dihydrooxazole); 
a 2,2'-(arylene) bis (4,5-dihydrooxazole), e.g. 2,2'-(1,4-phenylene) bis 
(4,5-dihydrooxazole), 2,2'-(1,5-naphthalenyl) bis (4,5-dihydrooxazole) and 
2,2'-(1,8-anthracenyl) bis (4,5-dihydrooxazole); a sulfonyl, oxy, thio or 
alkylene bis 2-(arylene) (4,5-dihydrooxazole), e.g., sulfonyl bis 
2-(1,4-phenylene) (4,5-dihydrooxazole), oxy bis 2-(1,4-phenylene) 
(4,5-dihydrooxazole), thio bis 2-(1,4-phenylene) (4,5-dihydrooxazole) and 
methylene bis-(1,4-phenylene) (4,5-dihydrooxazole); a 2,2',2"-(arylene) 
tris (4,5-dihydrooxazole), e.g., 2,2',2"-(1,3,5-phenylene) tris 
(4,5-dihydrooxazole); a poly(2-alkenyl) 4,5-hydrooxazole), e.g., 
poly(2-(2-propenyl) 4,5-dihydrooxazole), and the like. 
Representative compounds having at least two aromatic hydroxyl groups per 
molecule which are useful in the process of this invention include the 
various benzene and fused aromatic ring diols and triols, e.g., 
1,4-benzene diol (hydroquinone), 1,3-benzenediol (resorcinol), 
1,4-haphthalene diol and 1,3,5-benzenetriol; the biphenyl diols, e.g., 
(1,1'biphenyl)-2,2'-diol; the alkylene and cycloalkylene bisphenols, e.g., 
2,2'-methylene bisphenol, 4,4'(1-methylethylidene) bisphenol (Bisphenol 
A), 4,4'-phenylmethylene) bisphenol, 4,4'-cyclohexanediyl)bisphenol, 
4,4'-(1,2-diethyl-1,2-ethenediyl) bisphenol, and 
3,4-bis(4-hydroxyphenyl)-2,4-hexadiene; the arylene bisphenols, e.g., 
4,4'-phenylene bisphenol; the oxy, thio and sulfonylbisphenols, e.g., 
2,3-oxybisphenol, 4,4'-thiobisphenol and 2,2'sulphonyl bisphenol; the 
bis(hydroxyaryl) alkanones, e.g., bis (4-hydroxyphenyl) methanone, 
1,5-dihydroxy-9,10-anthracenedione and 
4-(bis(4-hydroxyphenyl)methylene)-2,5-cyclohexadiene-1-one; the various 
benzamide and benzoate derivatives, e.g., 2-hydroxy-N-(4-hydroxyphenyl) 
benzamide, 4-hydroxy-4-hydroxyphenyl benzoate, 
2-methyl-2-(4-hydroxybenzoyl)oxymethyl-1,3-propanediyl- 4-hydroxybenzoate, 
bis (4-hydroxy benzoate)-1,2-ethandiyl; 2-(4-hydroxybenzoate) ethyl ether, 
bis (4-hydroxybenzamide)-1,6-hexanediyl and bis (4-hydroxy 
benzamide)-1,4-benzenediyl. 
The above-described oxazoline and phenolic compounds are, as specifically 
indicated, illustrative of the respective types of compounds useful in the 
practice of this invention. Besides the various isomers of these 
representative compounds, a broad variety of substituted compounds are 
likewise applicable. In respect of the latter compounds, the sole 
requirement being that the substituent group is not reactive with either 
an oxazoline or an aromatic hydroxyl group. Examples of such substituent 
groups include alkyl, aryl, halo, cyano, nitro, alkoxy, aryloxy, alkyl and 
aryl sulfides, amine and alkyl or aryl substituted amine, amide, ester, 
and the like. 
In addition to the phenolic compounds noted above, a variety of oligomers 
containing a plurality of phenolic residues constitute an important class 
of materials for reacting with the bis-oxazolines in accordance with this 
invention. Particularly representative of such oligomers are the base or 
acid catalyzed phenol formaldehyde condensation products preferably the 
latter condensates; viz., the novalaks. Besides the conventional resoles, 
the phenolic resins characterized in having benzylic ether linkages 
prepared by metal ion catalysis such as disclosed in U.S. Pat. No. 
3,485,797 are applicable. Other suitable polyphenol oligomers include the 
addition polymers and copolymers of a vinyl substituted phenol such as 
4-ethenyl phenol. 
The process of this invention is preferably carried out in the absence of a 
solvent or diluent. The process is preferably carried out in the melt 
phase which usually constitutes the mode of choice in the preparation of 
matrix resins in the production of composites which represents a prime 
utility of the materials of the present invention. In some cases, it may 
be desirable to carry out the initial polymerization reaction in solution 
employing a high boiling aprotic solvent such as, for example, 
N.N-dimethylacetamide, N,N-dimethylformamide, 1-methyl-2-pyrrolidone, 
dimethyl sulfoxide, and the like. The polymerization product in such a 
case can then be isolated and curing completed in a subsequent molding 
operation, in the presence of the cationic catalyst. 
The reaction temperature for both of the indicated methods of preparation 
broadly ranges from about 100 degrees C. to 200 degrees C. In preparing 
thermoplastic and thermoset compositions, the preferred stoichiometry 
ranges from 0.1-1.0 equivalent of phenolic reactant per equivalent of 
oxazoline. The use of a catalyst in the process of this invention is 
required. Applicable catalysts for use in the process of this invention 
are those of the formula M(X)n wherein M represents an alkali metal or an 
alkaline earth metal moiety,, X represents BF.sub.4, PF.sub.6, BPh.sub.4, 
ClO.sub.4 and the like, wherein pH represents phenyl and n represents 1 or 
2. The catalyst is effective when used in from 0.2 to 10% by weight based 
on the weight of oxazoline.

The process of this invention is further illustrated in the following 
representative examples. 
EXAMPLE 1 
This example, which is outside the scope of the present invention, 
demonstrates the formation of a thermoplastic polymer by reaction between 
a bis-oxazoline and a bis-phenolic material in the absence of the catalyst 
of this invention. The bis-oxazoline used was 2,2'-(1,4-phenylene) 
bis(4,5-dihydrooxazole) (10.0 g) which was mixed with 3.5 g of resorcinol 
and the mixture was heated at 160 degrees C. for 31/2 hours to give a 
thermoplastic polymeric material which was found to have a melting point 
of about 75 degrees C. and was soluble in solvents such as 
N-methyl-2-pyrrolidinone (NMP) and dimethyl formamide (DMF). 
EXAMPLE 2 
The bis-oxazoline and resorcinol of Example 1 plus a catalyst were employed 
in this example. Resorcinol (3.5 g) and lithium fluoborate (0.2 g) were 
mixed and heated at 120 degrees C. to give a purple colored solution. To 
this solution were added 10 g of the bis-oxazoline melt and the mixture 
was brought to 160 degrees C. in the form of a melt. A rapid gellation 
took place in the mixture within 20 seconds of the mixing to give a 
thermoset polymer which was postcured at 175 degrees C. for one hour. The 
resulting polymer was insoluble in DMF and NMP. The polymer was found to 
have a Tg by DSC (Differential scanning calorimetry) of 160 degrees C. and 
a 10% weight loss in nitrogen by TGA (thermogravimetric analysis) occured 
at about 400 degrees C. 
EXAMPLE 3 
The procedure of Example 2 was followed using 10 g of the bis-oxazoline, 
2.5 g of resorcinol and 0.1 g of lithium fluoborate. Gellation occurred 
within 30 seconds at about 160 degrees C. to give a thermoset polymer 
which was insoluble in DMF and NMP. The polymer which was postcured at 175 
degrees C. for two hours showed no distinct transition (Tg) below 300 
degrees C. and 10% weight loss by TGA occurred at about 388.4 degrees C. 
EXAMPLE 4 
The procedure of Example 2 was followed using 10 g of bis-oxazoline, 2 g of 
resorcinol and 0.1 g of lithium fluoborate. The thermoset polymer formed 
within one minute of heating at 160 degrees C. and was found to be 
insoluble in DMF (dimethyl formamide) and NMP (N-methyl pyrrolidone) The 
polymer had no distinct Tg below 300.degree. C. and the decomposition 
temperature was about 393.degree. C. 
EXAMPLE 5 
The procedure of Example 2 was followed using 12 g of the bis-oxazoline of 
Example 2, 5 g of an oligomeric phenol resin obtained by 
phenol/formaldehyde condensation (equivalent weight of 90-100) and 0.2 g 
of lithiium fluoborate. The resulting mixture was heated at 160 degrees 
C., gellation occured within five minutes and the resulting polymer was 
postcured at about 165.degree. C. for two hours. The final thermoset 
polymer was found to be insoluble in DMF and DMP. The Tg for this polymer 
by DSC was found to be 200.degree. C. and decomposition occurred at 
370.degree. C.