DETAILED DESCRIPTION OF THE INVENTION Poly-2-oxazolines, also known as N-acylated, linear polyalkylenimines, are used in the practice of this invention.
Poly-2-oxazolines are known compounds consisting of n randomly-joined units (I, II) and are readily prepared by the ring-opening polymerization of 2-oxazolines or like compounds (III), followed by either full or partial hydrolysis.
##STR1## 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, stannous 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 polyethylen- or polypropylenimines having a molecular structure consisting essentially of repeating units (I).
These polymers are easily converted (deacylated) to the phosphate salt by acid hydrolysis with phosphoric acid.
The partially deacylated poly-2-oxazolines, i.
e.
, the phosphate salts of poly-2-oxazoline, have a molecular structure consisting essentially of the randomly-joined units (I) and (II), illustratively depicted as: ##STR2## 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 phosphorylated (deacylated) units.
The phosphate salts of the poly-2-oxazolines here used include both the fully and partially phosphorylated polymers.
Partially phosphorylated poly-2 -oxazolines have at least one phosphorylated secondary amine group ##STR3## per polymer chain as in (IV) where n-h is at least 1
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