Hollow Polymeric Microstructures with Controlled Porosity

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Solution Overview

Problem

Current methods for creating nanoscale and mesoscale spherically-shaped hollow spheres with monolithic, polymeric shells that enclose cavities are limited in precision and functionality, particularly in controlling transport rates and interactions with the environment.

Innovation Solution

A method involving the deposition of a polymeric precursor material on a spherically-shaped particle, followed by polymerization to form a porous, monolithic shell, and subsequent removal of the particle, creating a cavity defined by the shell, which can be tailored for specific dimensions and functionalities such as porosity and coating for desired properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional microfabrication molding processes are used to create hollow spheres, then manufacturing simplicity is maintained, but manufacturing precision and control over transport properties are insufficient

Engineering Contradiction:

Improvecontrol over transport propertiesVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The manufacturing process is divided into distinct sequential steps: depositing polymeric precursor material on spherical particles, polymerizing the precursor to form a shell, and removing the core particles to create hollow structures. This segmentation allows precise control over each step's parameters, particularly the deposition conditions that determine transport properties, while maintaining overall process simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Spherical particles are used as preliminary templates or cores before the polymeric shell is formed around them. This preliminary action establishes the desired spherical geometry and size distribution early in the process, enabling precise control over the final hollow sphere dimensions and transport characteristics without requiring complex post-processing.

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If polymeric precursor material is deposited and polymerized to form a monolithic shell, then shell integrity and monolithic structure are achieved, but porosity control becomes challenging

Engineering Contradiction:

Improvemonolithic shell integrityVSAvoidporosity control

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The polymeric shell is designed with controlled porosity by adjusting the polymerization conditions and precursor material composition. The porous structure is integrated into the monolithic shell formation process, allowing the shell to maintain structural integrity while possessing tunable transport properties through controlled pore size and distribution.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

Porosity is controlled by changing physical and chemical parameters during the polymerization process, such as temperature, pressure, catalyst concentration, and precursor composition. These parameter changes enable precise tuning of the shell's porous structure and transport properties while maintaining the monolithic integrity of the overall shell structure.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If hollow spheres with specific dimensions are fabricated, then application-specific functionality is achieved, but manufacturing precision and dimensional control are difficult to achieve

Engineering Contradiction:

Improvedimensional controlVSAvoidfabrication simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The polymeric precursor material is deposited with controlled local thickness and composition on the spherical particle surface. This local quality control during deposition enables precise dimensional control of the final hollow spheres, allowing different regions or aspects of the shell to have optimized properties for specific applications while maintaining ease of manufacture through a single deposition process.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables the fabrication of nanoscale and mesoscale structures with controlled transport properties and environmental interactions, suitable for various applications including drug delivery, thermal management, and electromagnetic shielding.

Implementation Method 1

depositing a polymeric precursor material on a surface of the spherically-shaped particle

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

polymerizing the precursor material to produce the porous, monolithic shell

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentUS7387813B2Methods of preparation of hollow microstructures and nanostructures

Publication Date: 2008.06.17 SPECIALTY COATING SYSTEMS INC

AI summary

Structures in the nanoscale and mesoscale domain are provided. The structures typically have a shell which can be comprised of a porous polymeric material such as parylene. The surfaces of the shell can further comprise pendant functional groups that can provide reactive or passive characteristics.