2-Acrylamido-2-methylpropane sulfonic acid vinyl aminimide/copolymer

DETAILED DESCRIPTION OF THE INVENTION The novel copolymers of the present invention are prepared by conventional vinyl polymerization techniques such as free radical polymerization techniques.
Although the monomers may be combined in substantially any ratio, if relatively high conductivity is desired it is preferred to employ at least 50% by weight of 2-acrylamido-2-methylpropane sulfonic acid.
In a particularly preferred embodiment, at least 80% by weight is employed.
The following non-limiting examples illustrate the preparation of the novel copolymers of the present invention.
EXAMPLE 1 The following materials were placed in a glass vessel:
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2-acrylamido-2-methylpropane sulfonic acid
17.
4 g.

##STR3##
Trimethylamine acrylimide
2.
6 g.

Water 108.
0 g.

Azobisisobutyronitrile 10 mg.

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The mixture was heated under a blanket of nitrogen at 65.
degree.
C.
for 30 hours.
An aqueous viscous solution of the copolymer was obtained.
EXAMPLE 2 The following materials were placed in a glass vessel:
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2-acrylamido-2-methylpropane sulfonic acid
16.
0 g.

##STR4## 4.
0 g.

Trimethylamine N-acryloyl-methylalaninimide
Water 108.
0 g.

Azobisisobutyronitrile 10 mg.

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The mixture was heated under a blanket of nitrogen for 3 days at 65.
degree.
C.
An aqueous solution of the copolymer was obtained having a viscosity of about 5000 cps (Brookfield No.
4 spindle, 60 rpm at 25.
degree.
C.
).
The novel copolymers of the present invention possess unusual salt stability while retaining their viscosity.
This property makes the copolymers particularly suitable for use in the procedures set forth in the above-mentioned application Ser.
No.
672,647.