Thermoassociative Copolymer Additives for Lubricant Viscosity Control
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Solution Overview
Problem
High molecular weight polymers used in lubricating compositions have low permanent shear resistance, leading to irreversible degradation under shear stress, and their viscosity is not effectively modulated by temperature, resulting in poor lubricating properties, especially during engine start-up and operation.
Innovation Solution
A mixture of a polydiol random copolymer and a random copolymer with boronic ester functions, combined with a diol compound, which allows for thermoreversible association and dissociation, controlling the viscosity and rheological behavior of the lubricating composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If high molecular weight polymers are used to increase viscosity, then the thickening effect is improved, but the permanent shear resistance deteriorates due to chain degradation under shear stress
Solution Approach 1:
The polymer is segmented into smaller units through controlled shear degradation, but these segments are held together by reversible associative bonds (hydrogen bonds, dipole-dipole interactions) that reform after shear stress is removed, maintaining both processability under shear and recovery of viscosity
Solution Approach 2:
The patent changes the physical-chemical parameters of the polymer by introducing functional groups capable of reversible association (hydroxyl, carboxyl, amine groups) that can form and break bonds dynamically, allowing the polymer to adapt its structure in response to shear stress and temperature changes
2Duration of action of stationary object
If high molecular weight polymers are used to increase viscosity, then the thickening effect is improved, but the viscosity cannot be effectively modulated by temperature
Solution Approach 1:
The patent introduces dynamic reversible bonds that can form and break depending on temperature conditions, allowing the polymer structure to be more flexible at high temperatures (reducing viscosity) and more associated at low temperatures (increasing viscosity), thus achieving temperature-responsive viscosity modulation
Solution Approach 2:
The reversible associative bonds undergo phase-like transitions in their association state based on temperature, with stronger association at lower temperatures and weaker association at higher temperatures, enabling the polymer to modulate its effective viscosity in response to thermal conditions
3Duration of action of stationary object
If high molecular weight polymers are used, then the thickening effect is improved, but the lubricating properties during cold start-up deteriorate due to excessive viscosity
Solution Approach 1:
The reversible associative bonds provide dynamic adaptability, allowing the polymer to reduce its effective viscosity during cold start-up conditions when shear rates are high and temperature is low, improving pumpability and cold-flow properties while maintaining thickening capability under normal operating conditions
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
The composition provides stable lubricating properties across temperature variations, ensuring effective lubrication during both cold start-up and hot operation phases by modulating viscosity and rheological behavior.
Implementation Method 1
a random copolymer A2 comprising at least two boronic ester functions and capable of associating with said polydiol random copolymer A1 by at least one transesterification reaction
Data Source
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AI summary
The invention relates to novel compositions of additives resulting from the mixture of at least two thermoassociative and exchangeable copolymers and at least one compound allowing the association of said two copolymers to be controlled. The invention also relates to a lubricating composition resulting from the mixture of at least one lubricating base oil, at least two thermoassociative and exchangeable copolymers and at least one compound allowing the association of said two copolymers to be controlled. The invention also relates to a method for modulating the viscosity of a lubricating composition resulting from the mixture of at least one lubricating base oil, and at least two thermoassociative and exchangeable copolymers, and to the use of a diol compound for modulating the viscosity of a lubricating composition.