# US 4,400,496 A · Water-soluble graft copolymers of starch-acrylamide and uses therefor

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- Number: US 4,400,496 A
- Document ID: US4400496A
- Status: Granted
- Kind: A
- Application number: 06/188,999
- Filed: 1980-09-22
- Granted: 1983-08-23
- Earliest claimed: 1980-09-22
- Assignees: University of Florida
- Inventors: George B. Butler; Thieo E. Hogen-Esch; John J. Meister; Huey Pledger, Jr.
- Web page: https://patentgrep.com/patent/US4400496A

## CPC

- C08F 251/00: Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS

## Abstract

Graft copolymers having starch as the central chain with grafted side chains of acrylamide or acrylamide-acrylic acid, and a process for preparation of such copolymers in the presence of Ce.sup.+4 or other redox initiators. These copolymers are employed in preparing highly viscous aqueous solutions that are particularly useful in oil recovery from subterranean wells.

## Claims

### Claim 1

Water-soluble graft copolymer comprising a backbone molecule of water-soluble starch with branch chains grafted thereto of polymerized acrylamide units or a mixture of polymerized acrylamide units and polymerized acrylic acid units.

### Claim 2 (depends on 1)

The graft copolymer of claim 1 wherein all of said branch chains are polymerized acrylamide.

### Claim 3 (depends on 1)

The graft copolymer of claim 1 which has the property of increasing the viscosity of water from 2 to 1000 times that of pure water when dissolved in water at concentrations of 0.001 to 2.0 weight percent.

### Claim 4 (depends on 1)

The graft copolymer of claim 1 having a molecular weight of 300,000 to 20,000,000.

### Claim 5 (depends on 3)

The graft copolymer of claim 3 in which the molecular weight is 1,000,000 to 5,000,000 and each starch molecule has 1-18 of said grafted branch chains.