Polymeric microspheres

• US 6,720,007 B2
• Filed: 10/25/2001
• Issued: 04/13/2004
• Est. Priority Date: 10/25/2000
• Status: Expired due to Fees

• Current Assignee: Tufts University
• Original Assignee: Tufts University
• Inventors: Walt, David R., Fleming, Michael S., Mandal, Tarun K.
• Primary Examiner(s): Page, Thurman K.
• Assistant Examiner(s): DI NOLA BARON, LILIANA
• Application Number:
  US10/033,389
• Publication Number:
  US 20020172716A1
• Time in Patent Office: 901 Days
• Field of Search: 424/489, 424/490, 424/497, 424/724, 424/484, 424/486, 424/487
• US Class Current: 424/489
• CPC Class Codes: A61K 9/5089 Processes
• CPC Class Codes: A61K 9/5138 obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polyvinyl pyrrolidone, poly(meth)acrylates
• CPC Class Codes: A61K 9/5146 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. polyethylene glycol, polyamines, polyanhydrides
• CPC Class Codes: B01J 13/02 Making microcapsules or microballoons for medical preparations A61K9/50
• CPC Class Codes: B01J 13/14 Polymerisation; cross-linking
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

The invention features core-shell microsphere compositions, hollow polymeric microspheres, and methods for making the microspheres. The microspheres are characterized as having a polymeric shell with consistent shell thickness.

Claims

1. A method for preparing a hollow microsphere, comprising:

providing a substrate comprising a plurality of hydroxyl groups;

attaching an initiator agent to said hydroxyl groups to form attached initiator agents;

reacting the attached initiator agents with a polymerizable unit under living polymerization conditions to form a polymer shell over said substrate, said polymerization being confined to a surface of said substrate; and

exposing said substrate to an etching agent for a time sufficient to allow for removal of said substrate from said polymeric shell to form a hollow microsphere.

2. The method of claim 1, wherein said substrate is silica.

3. The method of claim 1, wherein said substrate is selected from the group consisting of silica, alumina, mica, and clay.

4. The method of claim 1, further comprising exposing said polymer shell to a crosslinking agent.

5. The method of claim 1, wherein said polymerizable unit is selected from the group consisting of acrylonitrile, styrene, benzyl methacrylate, phenyl methacrylate, ethyl methacrylate, divinyl benzene, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, p-methyl styrene, acrylamide, methacrylamide, methacrylonitrile, hydroxypropyl methacrylate, methoy styrene, N-acrylylglycinamide, and N-methacrylylglycinamide.

6. The method of claim 1, wherein said polymerizable unit is selected from the group consisting of styrene-PMMA, benzyl methacrylate-PMMA, styrene-PHEMA, styrene-PEMA, styrene-methacrylate, and styrene-butylacrylate.

7. The method of claim) wherein said initiator agent is selected from the group consisting of phenyl ethyl chloride, phenyl ethyl bromide, phenyl sulfonyl chloride, and 2-bromoethylisobutyrate.