Oligourea Nanoparticle Synthesis via Depolymerization Control
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Solution Overview
Problem
Current methods for producing oligourea dispersions from polyurethane plastics result in particles with wide particle size distributions and larger sizes, failing to achieve molecularly uniform particles in the nanometer range without water and with reactive groups for specific end-use applications.
Innovation Solution
A process involving the reaction of starting compounds with hydroxyl or thiol groups and di- or polyisocyanates to form polyurethane or polythiourethane compounds, followed by depolymerization at a higher temperature in the presence of amines, which controls the formation of oligomeric urea compounds with narrow particle size distributions and reactive groups, using a dispersant or the cleavage products as solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If oligourea dispersions are produced by depolymerization of polyurethane plastics using conventional methods, then oligourea particles are obtained, but the particle size distribution is wide (100 to 10000 nm half-width) and particle sizes are large (200-500 nm)
Solution Approach 1:
The patent applies parameter changes by systematically varying reaction conditions including temperature (60-100°C for polyurethane formation, then higher for depolymerization), isocyanate-to-polyol ratios (0.8:1 to 1.2:1), catalyst types and amounts, and reaction times to achieve precise control over particle size distribution and narrow it to 10-50 nm half-width
Solution Approach 2:
The patent employs dynamic control of the depolymerization process by gradually increasing temperature from 60-100°C to higher temperatures, continuously monitoring particle formation, and adjusting reaction conditions in real-time to maintain optimal particle size distribution throughout the process
2Ease of manufacture
If water is used in the depolymerization process, then the reaction proceeds easily, but the resulting oligourea particles contain water which interferes with subsequent reactions
Solution Approach 1:
The patent uses inert or aprotic solvents such as chlorinated solvents (dichloromethane, chloroform), fluorinated solvents (perfluorohexane), or carboxylic acid solvents instead of water to create an inert reaction environment that prevents water interference with subsequent reactions while still enabling the depolymerization process to proceed effectively
Solution Approach 2:
The patent introduces catalysts such as organometallic compounds (tin octoate, zinc stearate), organic bases (DMAP, pyridine), or acids (p-toluenesulfonic acid) as intermediaries to facilitate the depolymerization reaction in non-aqueous environments, enabling the reaction to proceed without water while maintaining high efficiency
3Productivity
If conventional depolymerization methods are used, then oligourea particles are released from foam structure, but the particles lack controlled functional groups for specific end-use applications
Solution Approach 1:
The patent applies local quality by introducing different functional groups at specific locations on the oligourea molecules through selective reaction conditions, catalyst choices, and solvent systems, enabling different regions of the oligourea structure to possess different functional characteristics tailored for specific applications such as adhesives, coatings, or textiles
Solution Approach 2:
The patent produces composite oligourea structures by combining multiple functional groups (hydroxyl, amine, carboxyl, isocyanate) within the same oligourea molecule or within the dispersion system, creating multifunctional materials that can perform multiple roles in end-use applications
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 produces oligourea molecules with degrees of oligomerization of 2 to 16, primarily in the range of 2 to 8, resulting in nanoscale particles with uniform sizes and functional groups, enabling their use in end products through reactions with other components.
Implementation Method 1
depolymerization of the resulting polyurethane and/or polythiourethane compounds in the presence of a primary or secondary di- or polyamine at a second reaction temperature
Implementation Method 2
The depolymerization caused by the increase in temperature causes the urethane bond to split
Implementation Method 3
free isocyanate groups that are preferably present react with the amine, in particular before the depolymerization
Implementation Method 4
The starting compounds made accessible by depolymerization or any unreacted starting compounds act as diluents or dispersants
Data Source
Figure 1~2
AI summary
The invention relates to a method for producing oligourea compounds by chain building and depolymerization, to oligourea dispersions, and to their use as fungicides, biocides and/or herbicides.