Fluorine Polymer Microspheres via Liquid CO2 Photopolymerization
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Solution Overview
Problem
The synthesis of polymer microspheres using carbon dioxide as a reaction medium is hindered by the need for high temperatures and pressures, leading to increased equipment costs and slow reaction processes, which impede the application of carbon dioxide in preparing microspheres for coatings due to rapid curing and poor diffusion of microspheres onto the coating surface.
Innovation Solution
The use of photo-dispersion polymerization with liquid carbon dioxide as a reaction medium, incorporating a fluorine-containing polymer with a RAFT macromolecular chain and tertiary amine groups to reduce surface energy and facilitate bonding of microspheres into a cross-linked network, allowing for timely migration and stable anchoring onto the coating surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional thermal polymerization is used with carbon dioxide as reaction medium, then polymer microspheres can be synthesized, but high temperature and pressure are required leading to increased equipment cost and slow reaction process
Solution Approach 1:
The patent replaces thermal energy input with optical energy (light) to initiate polymerization. By using photoinitiators that absorb light and generate radicals, the process eliminates the need for high-temperature heating equipment, thereby reducing equipment costs while maintaining or improving reaction speed through controlled photo-initiation.
Solution Approach 2:
The patent changes the reaction conditions from thermal parameters (high temperature >50°C, high pressure >200 bars) to photochemical parameters (light wavelength, light intensity, photoinitiator concentration). This parameter transformation allows the reaction to proceed under milder conditions with liquid CO2, reducing equipment requirements and enabling faster reaction rates.
2Productivity
If traditional thermal polymerization is used with carbon dioxide as reaction medium, then polymer microspheres can be synthesized, but the reaction process becomes slow
Solution Approach 1:
By substituting thermal activation with photochemical activation, the patent achieves rapid initiation of polymerization upon light exposure. The photoinitiators absorb light energy and immediately generate radicals that trigger fast chain growth, significantly reducing reaction time compared to slow thermal processes while increasing productivity.
Solution Approach 2:
The patent employs controlled irradiation where light is applied in a regulated manner to initiate and control the polymerization rate. By adjusting light intensity and exposure duration, the reaction can be optimized for speed without sacrificing control, thereby reducing overall reaction time while maintaining high productivity.
3Strength
If filling microspheres are used in photocurable coatings with high solid contents, then coating properties are improved, but rapid curing prevents microspheres from diffusing timely onto the coating surface
Solution Approach 1:
The patent performs polymerization in advance to pre-form the microspheres with their surface-modified fluoropolymer shells before incorporating them into the coating formulation. This preliminary synthesis ensures that microspheres are ready for immediate diffusion upon coating application, eliminating delays and ensuring timely migration to the coating surface during the curing process.
Solution Approach 2:
The patent modifies the surface properties of microspheres by grafting fluoropolymer chains onto them, which reduces surface energy and enhances mobility. This parameter change in surface chemistry allows microspheres to diffuse more rapidly through the coating matrix during curing, ensuring timely arrival at the coating surface without compromising coating strength.
4Ease of manufacture
If carbon dioxide is used in supercritical state for polymerization, then reaction can proceed, but higher reaction pressure is required leading to higher equipment cost
Solution Approach 1:
The patent changes the physical state of CO2 from supercritical to liquid by adjusting temperature and pressure parameters. By conducting photopolymerization in liquid CO2 at lower pressures (avoiding the supercritical region), the equipment requirements are significantly reduced, lowering costs while maintaining effective reaction conditions through photochemical initiation.
Solution Approach 2:
By replacing thermal activation with photochemical activation, the patent eliminates the need for high-pressure equipment required for supercritical CO2 processes. The photopolymerization can proceed efficiently in liquid CO2 at moderate pressures, thereby reducing equipment complexity and cost while maintaining productivity.
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 reduces the manufacturing cost and time of polymerization, enhances the stability and performance of the cured coating by ensuring timely migration and tight bonding of microspheres, and improves the solubility and nucleation process, resulting in efficient and energy-efficient microsphere synthesis.
Implementation Method 1
an initiating light source is used to irradiate inside the reactor so as to carry out a photoinitiation reaction
Implementation Method 2
The fluorine-containing polymer covering the surface of the polymer microspheres according to the present invention can reduce the surface energy thereof
Implementation Method 3
the tertiary amine groups introduced into the fluorine-containing polymer firmly bond microspheres into a cross-linked network
Implementation Method 4
liquid carbon dioxide as a reaction medium... The use of carbon dioxide fluid in place of traditional organic solvents as a reaction medium for synthesizing polymers
Data Source
AI summary
Disclosed in the invention is a fluorine-containing polymer microsphere. A polymerization monomer, a photoinitiator and a stable dispersant are added into a reaction kettle, carbon dioxide gas is introduced for emptying air therein, then liquid carbon dioxide is injected, an initiating light source is used for irradiating in the reaction kettle after the temperature and pressure of the reaction kettle are constant, the reaction is performed under the conditions of −20-30° C. and 20-70 bar, wherein the concentration of the polymerization monomer accounting for the total volume of the reactants is 0.02-2 g/ml, and the weight ratio of the photoinitiator, stable dispersant and polymerization monomer is (0.3-10):(2-20):100; after the reaction is finished, the temperature returns to room temperature, and the precipitate is washed with liquid carbon dioxide, so as to obtain the polymer microspheres. The fluorine-containing polymer which covers the surface of the microspheres in the present invention can reduce the surface energy thereof, and can benefit the timely migration of the microspheres to the coating surface; a tertiary amine group is introduced into the fluorine-containing polymer to firmly bond the microspheres into a cross-linked network, and thus benefits the tight integration of the microspheres and the coating; a RAFT active group is introduced to firmly anchor the microspheres onto the coating film; thus ensuring the stability of the cured coating.