Method for surface functionalisation in a supercritical fluid medium
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Solution Overview
Problem
Existing methods for surface functionalization of polymeric organic matrices in biological and medical engineering face challenges in achieving durable modifications without using isocyanate compounds and minimizing residue formation, particularly in controlling surface properties like wettability and scratch resistance.
Innovation Solution
A method involving the use of a supercritical fluid medium, specifically supercritical carbon dioxide, for covalent grafting of molecules with blocked isocyanate functions onto substrates with labile hydrogen functions, eliminating the need for isocyanate compounds and reducing the use of solvents and by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional surface functionalization methods are used to achieve durable covalent grafting, then long-lasting substrate functionalization is achieved, but isocyanate compounds and surfactants are used which leave difficult-to-remove residues
Solution Approach 1:
The patent introduces supercritical CO2 as an intermediary carrier medium that enables the transport and delivery of functional molecules to the substrate surface without leaving harmful residues. The supercritical fluid acts as a clean intermediary that can be completely removed after the process, unlike conventional solvents and surfactants that leave difficult-to-remove residues.
Solution Approach 2:
The patent utilizes changes in physical parameters (temperature and pressure) to transition CO2 between supercritical and gaseous states. By controlling these parameters, the CO2 carrier can be introduced in supercritical form for efficient mass transfer, then easily removed by depressurization, leaving no residues on the functionalized substrate.
2Strength
If isocyanate compounds are used for covalent grafting, then strong covalent bonds are formed on the substrate surface, but the use of isocyanates is restricted by environmental regulations
Solution Approach 1:
The patent extracts the harmful isocyanate compound from the process and replaces it with alternative functional molecules that can be delivered via supercritical CO2. The active functional groups are introduced in a controlled manner through the supercritical carrier, eliminating the need to handle and store hazardous isocyanates while still achieving covalent grafting.
Solution Approach 2:
The patent employs disposable or easily removable functional molecules delivered through supercritical CO2. The supercritical CO2 itself acts as a temporary, disposable carrier that is completely eliminated after the process by simple depressurization, leaving no persistent harmful substances on the substrate.
3Quantity of substance
If conventional solvents are used for substrate impregnation, then good solvent properties are achieved, but solvent recycling and treatment are required
Solution Approach 1:
The patent exploits the phase transition properties of CO2 between supercritical and gaseous states. By adjusting pressure and temperature, CO2 can be introduced in a supercritical state for excellent solvent and impregnation properties, then easily converted to a gaseous state for complete removal and recycling, eliminating the need for complex solvent treatment processes.
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 approach allows for durable surface functionalization with minimal environmental impact, avoiding the use of isocyanates and solvents, while enabling efficient covalent bonding and easy elimination of by-products, thus optimizing surface properties without the need for additional processing steps.
Implementation Method 1
carried out in a supercritical fluid medium, in particular in a supercritical carbon dioxide medium
Implementation Method 2
subject the assembly to a temperature sufficient to cause the unblocking of said blocked isocyanate function borne by the molecule
Data Source
Figure 1~2
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AI summary
Method for surface functionalisation in a supercritical fluid medium. The present invention relates to a method for functionalising the surface of a substrate, the method being carried out in a supercritical fluid medium and implementing at least the steps consisting of: (i) providing a substrate having labile hydrogen functions on the surface; (ii) bringing the substrate into contact, in a supercritical fluid, with at least one organic molecule carrying at least one blocked isocyanate function which can be activated by heating; and (iii) subjecting the whole to a temperature sufficient to cause the release of the blocked isocyanate function carried by the molecule, and the covalent grafting of the molecule by reaction of the isocyanate function with a labile hydrogen function on the surface of the substrate.