WATER SWELLABLE POLYMER MATERIALS

• US 20130087736A1
• Filed: 12/01/2010
• Published: 04/11/2013
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: University of Sydney
• Original Assignee: University of Sydney
• Inventors: Such, Christopher H., Davey, Timothy W., Nguyen, Duc N., Hawkett, Brian S., Baker, Matthew P., O'Brien, Caitlin C.
• Granted Patent: US 9,255,198 B2
• Time in Patent Office: Days
• US Class Current: 252/62.54
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: C08L 13/02 Latex
• CPC Class Codes: C09B 67/0013 with polymeric coatings
• CPC Class Codes: C09C 1/3072 Treatment with macro-molecular organic compounds
• CPC Class Codes: C09C 1/3676 Treatment with macro-molecular organic compounds
• CPC Class Codes: C09C 1/46 Graphite C09C1/0015 takes precedence
• CPC Class Codes: C09C 3/10 Treatment with macromolecular organic compounds C09C3/006 takes precedence
• CPC Class Codes: C09D 11/00 Inks
• CPC Class Codes: C09D 113/02 Latex
• CPC Class Codes: Y10S 977/734 Fullerenes, i.e. graphene-based structures, such as nanohorns, nanococoons, nanoscrolls or fullerene-like structures, e.g. WS2 or MoS2 chalcogenide nanotubes, planar C3N4, etc.
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer

Abstract

The invention provides a method of preparing an aqueous dispersion of polymer encapsulated particulate material, the method comprising:

providing a dispersion of the particulate material in a continuous aqueous phase, the dispersion comprising RAFT agent as a stabiliser for the particulate material; and
polymerising ethylenically unsaturated monomer under the control of the RAFT agent to form polymer at the surface of the dispersed particulate material, thereby providing the aqueous dispersion of polymer encapsulated particulate material;
wherein polymerisation of the ethylenically unsaturated monomer comprises:

• • (a) polymerising a monomer composition that includes ionisable ethylenically unsaturated monomer so as to form a base responsive water swellable RAFT polymer layer that encapsulates the particulate material; and
  • (b) polymerising a monomer composition that includes non-ionisable ethylenically unsaturated monomer so as to form an extensible, water and base permeable RAFT polymer layer that encapsulates the base responsive water swellable RAFT polymer layer.

Claims

1. A method of preparing an aqueous dispersion of polymer encapsulated particulate material, the method comprising:

providing a dispersion of the particulate material in a continuous aqueous phase, the dispersion comprising RAFT agent as a stabiliser for the particulate material; and

polymerising ethylenically unsaturated monomer under the control of the RAFT agent to form polymer at the surface of the dispersed particulate material, thereby providing the aqueous dispersion of polymer encapsulated particulate material;

wherein polymerisation of the ethylenically unsaturated monomer comprises;

(a) polymerising a monomer composition that includes ionisable ethylenically unsaturated monomer so as to form a base responsive water swellable RAFT polymer layer that encapsulates the particulate material; and

(b) polymerising a monomer composition that includes non-ionisable ethylenically unsaturated monomer so as to form an extensible, water and base permeable RAFT polymer layer that encapsulates the base responsive water swellable RAFT polymer layer.

2. The method according to claim 1 further comprising exposing the resulting polymer encapsulated particulate material to a basic aqueous environment such that the base responsive water swellable RAFT polymer layer swells and expands in volume, while at the same time the extensible, water and base permeable RAFT polymer layer stretches to accommodate within its confines the expanded volume of the swollen base responsive water swellable RAFT polymer layer.

3. The method according to claim 2 further comprising removing from the polymer encapsulated particulate material water within the swollen base responsive water swellable RAFT polymer layer, the effect of which causes the volume of that layer to be reduced, wherein the extensible, water and base permeable RAFT polymer layer remains in a stretched state so as to provide one or more voids in between the particulate material and the stretched extensible, water and base permeable RAFT polymer layer.

4. The method according to claim 1, wherein the monomer composition that is polymerised to form a base responsive water swellable RAFT polymer layer comprises at least about 3 wt ionisable ethylenically unsaturated monomer having ionisable acid functional groups.

5. The method according to claim 1, wherein the monomer composition that is polymerised to form an extensible, water and base permeable RAFT polymer layer comprises at least about 50 wt % of non-ionisable hydrophobic ethylenically unsaturated monomer.

6. The method according to claim 1, wherein the monomer composition that is polymerised to form an extensible, water and base permeable RAFT polymer layer comprises no more than about 10 wt % of hydrophilic ethylenically unsaturated monomer.

7. The method according to claim 2 further comprising crosslinking the so formed stretched extensible, water and base permeable RAFT polymer layer.

8. The method according to claim 1, wherein the RAFT agent that functions as a stabiliser for the particulate material is of general formula (1):

9. The method according to claim 8, wherein R¹ is an optionally substituted organic group selected from alkyl, alkenyl, alkynyl, aryl, acyl, carbocyclyl, heterocyclyl, heteroaryl, alkyloxy, alkenyloxy, alkynyloxy, aryloxy, acyloxy, carbocyclyloxy, heterocyclyloxy, heteroaryloxy, alkylthio, alkenylthio, alkynylthio, arylthio, acylthio, carbocyclylthio, heterocyclylthio, heteroarylthio, alkylalkenyl, alkylalkynyl, alkylaryl, alkylacyl, alkylcarbocyclyl, alkylheterocyclyl, alkylheteroaryl, alkyloxyalkyl, alkenyloxyalkyl, alkynyloxyalkyl, aryloxyalkyl, alkylacyloxy, alkylcarbocyclyloxy, alkylheterocyclyloxy, alkylheteroaryloxy, alkylthioalkyl, alkenylthioalkyl, alkynylthioalkyl, arylthioalkyl, alkylacylthio, alkylcarbocyclylthio, alkylheterocyclylthio, alkylheteroarylthio, alkylalkenylalkyl, alkylalkynylalkyl, alkylarylalkyl, alkylacylalkyl, arylalkylaryl, arylalkenylaryl, arylalkynylaryl, arylacylaryl, arylacyl, arylcarbocyclyl, arylheterocyclyl, arylheteroaryl, alkenyloxyaryl, alkynyloxyaryl, aryloxyaryl, arylacyloxy, arylcarbocyclyloxy, arylheterocyclyloxy, arylheteroaryloxy, alkylthioaryl, alkenylthioaryl, alkynylthioaryl, arylthioaryl, arylacylthio, arylcarbocyclylthio, arylheterocyclylthio, and arylheteroarylthio.

10. The method according to claim 8, wherein Z is an optionally substituted organic group selected from alkoxy, aryloxy, alkyl, aryl, heterocyclyl, arylalkyl, alkylthio, arylalkylthio, dialkoxy- or diaryloxy-phosphinyl [—

P(═

O)OR²₂], dialkyl- or diaryl-phosphinyl [—

P(═

O)OR²₂], acylamino, acylimino, amino, R₁—

(X)_n—

S— and

a polymer chain, and R² is selected from alkyl, alkenyl, aryl, heterocyclyl, and alkylaryl.

11. The method according to claim 1, wherein the RAFT agent that functions as a stabiliser for the particulate material is soluble in the continuous aqueous phase.

12. The method according to claim 1, wherein the RAFT agent that functions as a stabiliser for the particulate material is the only stabiliser is the only stabiliser present.

13. The method according to claim 1, wherein the base responsive water swellable RAFT polymer layer is formed by polymerising a monomer composition comprising methyl methacrylate, butyl acrylate and methacrylic acid and/or acrylic acid.

14. The method according to claim 1, wherein the extensible, water and base permeable RAFT polymer layer is formed by polymerising a monomer composition comprising styrene, methyl methacrylate and butyl acrylate.

15. The method according to claim 1, wherein the particulate material is selected from pigment, magnetic material, fullerene, and a combination thereof.

16. The method according to claim 2, wherein the basic aqueous environment is provided by an aqueous solution comprising an alkali metal base, ammonium hydroxide, alkaline earth metal base, C1-C4 aliphatic amine, or combination thereof.

17. Polymer encapsulated particulate material, the particulate material being encapsulated by a base responsive water swellable RAFT polymer layer comprising polymerised residue of ionisable ethylenically unsaturated monomer, wherein the base responsive water swellable RAFT polymer layer is encapsulated by an extensible, water and base permeable RAFT polymer layer that comprises polymerised residue of non-ionisable ethylenically unsaturated monomer.

18. The polymer encapsulated particulate material according to claim 17, wherein the base responsive water swellable RAFT polymer layer is swollen with water to provide for an expanded volume of that layer, and the extensible, water and base permeable RAFT polymer layer is in a stretched state to accommodate within its confines the expanded volume of the swollen base responsive water swellable RAFT polymer layer.

19. The polymer encapsulated particulate material according to claim 18, wherein water within the swollen base responsive water swellable RAFT polymer layer of the polymer encapsulated particulate material has been removed and the volume of that layer is reduced, and wherein the extensible, water and base permeable RAFT polymer layer remains in a stretched state so as to provide one or more voids in between the particulate material and the stretched, extensible, water and base permeable RAFT polymer layer.

20. A paint, filler, adhesive, primer or sealant product comprising polymer encapsulated particulate material according to claim 17.