Shaped Polymeric Microparticles via Solvent Softening Moulding
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Solution Overview
Problem
Existing methods for producing shaped polymeric microparticles are limited by the materials and shapes they can produce, are costly, and often result in interconnected particles or difficulty in maintaining specific microstructures, especially for non-spherical shapes and polymers with specific thickness requirements.
Innovation Solution
A method using pre-formed spherical microparticles, which are transformed into desired non-spherical shapes using a mould with microcavities, where the particles are softened by solvent or heat treatment below 60°C to prevent continuous layer formation, allowing for versatile shape and material options, and maintaining engineered properties like porosity or bioactive loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If microfluidics method is used to produce shaped microparticles, then precise shapes can be obtained, but the production rate is limited and the number of polymers and shapes is restricted
Solution Approach 1:
The invention uses pre-formed spherical microparticles as starting material, which have already been produced with controlled size and microstructure. This preliminary preparation allows the subsequent shaping step to focus only on morphology modification rather than complete particle formation, thereby increasing production rate while maintaining shape precision.
Solution Approach 2:
The invention introduces a mould with microcavities as an intermediary tool to transfer the desired shape from the mould cavity to the softening microparticles. This intermediary mechanism enables versatile shape production without requiring complex microfluidic channel geometries for each shape type.
2Adaptability or versatility
If moulding method is used to produce shaped microparticles, then various shapes can be obtained, but a continuous layer connects the microparticles making them remain connected
Solution Approach 1:
The invention applies local quality by using non-stick surface treatment on specific regions of the mould (the microcavity surfaces) to prevent adhesion. This localized modification ensures that particles release cleanly from the mould cavities without forming continuous connecting layers, while the rest of the system maintains its shaping function.
Solution Approach 2:
The invention employs a disposable or easily replaceable mould with microcavities that can be optimized for each shape requirement. Rather than attempting to modify a single mould for multiple shapes, different moulds can be used for different shape requirements, ensuring optimal particle separation for each application.
3Productivity
If moulding method is used with larger operating area, then more particles can be produced, but it becomes more difficult to avoid continuous layer formation
Solution Approach 1:
The invention segments the production process into individual microcavities within the mould, each acting as an independent particle formation zone. This segmentation into discrete cavities prevents continuous layer formation even when producing large batches, as each cavity isolates its particle formation process from others.
4Shape
If stretching method is used to produce shaped microparticles, then non-spherical shapes can be obtained, but the method is limited in shape variety and time-consuming
Solution Approach 1:
The desired shape is pre-defined in the mould cavity geometry before the shaping process begins. This preliminary design of the target shape in the mould eliminates the need for time-consuming stretching and deformation operations, as particles simply conform to the pre-configured cavity shape during the softening step.
5Ease of manufacture
If heat treatment above glass transition temperature is used to soften particles, then shaping can be achieved, but the microstructure and active agents may be compromised
Solution Approach 1:
The invention changes the softening parameter from high temperature (above glass transition) to low temperature solvent treatment. This parameter change allows particle softening and shaping at temperatures that do not compromise the microstructure or active agents, while still achieving the desired shape through solvent-induced plasticization.
Solution Approach 2:
A solvent is introduced as an intermediary substance to facilitate the softening process at low temperatures. The solvent acts as a mediator that temporarily plasticizes the polymer matrix, enabling shape conforming without requiring thermal energy that would damage sensitive components.
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
This method enables the production of a wide variety of non-spherical shapes with precise geometry and microstructure, applicable to any polymer size, while avoiding interconnected particles and preserving active agents, thus being cost-effective and versatile.
Implementation Method 1
the particles are softened by solvent or heat treatment below 60°C to prevent continuous layer formation
Implementation Method 2
the particles are softened by solvent or heat treatment below 60°C
Data Source
AI summary
Method for producing shaped polymeric microparticles of non-spherical shape, comprising the steps of: placing one or more microparticles of substantially spherical shape in a respective micro-cavity of a mold having the desired non-spherical shape; subjecting said microparticles to softening by exposure to a solvent or mixture of solvent/non-solvent, in the liquid or vapor state, adapted to plasticize the polymeric material constituting said microparticles, and possibly assisting the solvent plasticization process by heat treatment, not excluding the possibility, in less critical cases in terms of conservation of the microstructure, of carrying out heat treatment exclusively, at a temperature not exceeding 40% of the glass transition temperature of the polymer material; and removing said microparticles from the mold cavities.