Methods for fabricating microstructures

• US 9,238,309 B2
• Filed: 05/08/2009
• Issued: 01/19/2016
• Est. Priority Date: 02/17/2009
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: King, William P., Cannon, Andrew H.
• Primary Examiner(s): WOLLSCHLAGER, JEFFREY MICHAEL
• Application Number:
  US13/201,408
• Publication Number:
  US 20120043693A1
• Time in Patent Office: 2,447 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B29C 2033/426 Stampers
• CPC Class Codes: B29C 2043/025 forming a microstructure, i.e. fine patterning
• CPC Class Codes: B29C 2059/023 Microembossing
• CPC Class Codes: B29C 33/306 Exchangeable mould parts, e.g. cassette moulds, mould inserts moulds with exchangeable mould parts for injection moulding B29C45/2673; mounting of exchangeable mould inserts for injection moulding B29C45/2675
• CPC Class Codes: B29C 33/3857 by making impressions of one or more parts of models, e.g. shaped articles and including possible subsequent assembly of the parts
• CPC Class Codes: B29C 33/3878 used as masters for making successive impressions
• CPC Class Codes: B29C 33/3885 the mould parts being co-operating impressions
• CPC Class Codes: B29C 33/3892 Preparation of the model, e.g. by assembling parts
• CPC Class Codes: B29C 33/405 Elastomers, e.g. rubber B29C33/50 takes precedence
• CPC Class Codes: B29C 33/42 characterised by the shape of the moulding surface, e.g. ribs or grooves
• CPC Class Codes: B29C 33/424 Moulding surfaces provided with means for marking or patterning for injection moulding B29C45/372
• CPC Class Codes: B29C 45/2673 with exchangeable mould parts, e.g. cassette moulds B29C45/1756 takes precedence
• CPC Class Codes: B29D 2030/0612 Means for forming recesses or protrusions in the tyres, e.g. grooves or ribs, to create the tread or sidewalls patterns
• CPC Class Codes: B29D 2030/0616 Surface structure of the mould, e.g. roughness, arrangement of slits, grooves or channels
• CPC Class Codes: B29D 2030/726 Decorating or marking the sidewalls before tyre vulcanization protecting, decorating, marking tyre sidewalls B60C13/00
• CPC Class Codes: B29D 30/72 Side-walls
• CPC Class Codes: B29L 2030/002 Treads
• CPC Class Codes: B29L 2030/007 Sidewalls
• CPC Class Codes: B29L 2031/756 Microarticles, nanoarticles
• CPC Class Codes: B60C 11/00 Tyre tread bands; Tread patterns; Anti-skid inserts
• CPC Class Codes: B60C 13/001 : Decorating, marking or the like
• CPC Class Codes: B81C 1/00206 : Processes for functionalising a surface, e.g. provide the surface with specific mechanical, chemical or biological properties

Abstract

Described herein are casting and molding methods useful for making microstructured objects. By including a plurality of microfeatures on the surface of an object, other characteristics may be imparted to the object, such as increased hydrophobicity. Some of the casting and molding methods described herein further allow for manufacture of objects having both microfeatures and macro features, for example microfeatures on or within macro features or selected macro feature regions.

Claims

1. A method of making a microstructured object, the method comprising the steps of:

providing a semiconductor wafer;

patterning the semiconductor wafer with a preselected pattern of microfeatures;

molding an uncured first polymer to the patterned semiconductor wafer;

curing the first polymer, thereby forming a microstructured flexible polymer having the preselected pattern of microfeatures on a surface of the microstructured flexible polymer;

removing the microstructured flexible polymer from the patterned semiconductor wafer;

providing a macro mold having one or more macro scale features, wherein the macro scale feature of the macro mold is one of a recessed feature and a relief feature;

deforming at least a portion of the microstructured flexible polymer so as to conform the microstructured flexible polymer to at least a portion of the surface of the one or more macro scale features of the macro mold wherein the microstructured flexible polymer is placed so that a surface of the microstructured flexible polymer opposite to the surface having the preselected pattern of microfeatures faces the portion of the surface of the one or more macro scale features of the macro mold;

providing a large-area prototype having one or more macro scale features, wherein the macro scale feature of the large-area prototype is the other of a recessed feature and a relief feature;

depositing an uncured second polymer onto at least a portion of a surface of the one or more macro scale features of the prototype;

molding the uncured second polymer by bringing the macro mold and microstructured flexible polymer into contact with the prototype and the uncured second polymer;

curing the uncured second polymer, thereby making a microstructured second polymer having the preselected pattern of microfeatures;

releasing the macro mold and microstructured flexible polymer from the prototype and microstructured second polymer; and

casting or molding a material to the prototype and microstructured second polymer, thereby replicating the preselected pattern of microfeatures in at least a portion of a cast or molded object.

2. The method of claim 1, wherein at least a portion of the pattern of microfeatures of the microstructured flexible polymer is positioned on a curved surface of the macro mold and at least a portion of the pattern of microfeatures of the cast or molded object are positioned on a curved surface of the cast or molded object.

3. The method of claim 1 wherein in the deforming step at least a portion of the microstructured flexible polymer is deformed to radius of curvature selected over the range of 100 μ

m to 3 m, wherein at least a portion of the microstructured flexible polymer is deformed to a strain level selected over the range of 1% to 1300% or wherein at least a portion of the microstructured flexible polymer is deformed to radius of curvature selected over the range of 100 μ

m to 3 m and to a strain level selected over the range of 1% to 1300%.

4. The method of claim 1 wherein the microfeatures have dimensions selected over the range of 10 nm to 100 μ

m and a pitch of the microfeatures is selected over the range of 10 nm to 100 μ

m.

5. The method of claim 4, wherein at least a portion of microfeatures have an aspect ratio of height or depth to width of 1:

2 to 7;

1.

6. The method of claim 1 wherein 80% to 100% of at least a portion of the surface of the macro scale features is covered by the preselected pattern of microfeatures.

7. The method of claim 1 wherein the preselected pattern of microfeatures is replicated in each casting and/or molding step with a replication fidelity selected over the range of 50% to 100%.

8. The method of claim 1, wherein the material of the cast or molded object is tire rubber, thereby making a microstructured tire.