Star Polymer Lubricant via Controlled Radical Polymerization
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Solution Overview
Problem
Conventional polymers used as viscosity modifiers or dispersants in lubricating oils face challenges in achieving balanced low and high temperature viscometrics, shear stability, and polydispersity, often requiring additional components that compromise performance.
Innovation Solution
A process involving controlled radical polymerization using a chain transfer agent with a thiocarbonyl thio group and a free radical leaving group, combined with a polyvalent coupling agent, to produce polymers with reduced polydispersity and improved viscometric properties, capable of forming star-polymers and lubricating compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the molecular weight of a conventional linear viscosity modifier is increased, then the viscosity increases, but shear stability decreases
Solution Approach 1:
The patent segments the polymer structure by introducing star-shaped architectures with multiple arms radiating from a central core. This segmentation allows each arm to contribute to viscosity while the centralized core provides shear stability, resolving the contradiction between high viscosity and shear stability that plagues conventional linear polymers.
Solution Approach 2:
The patent employs composite polymer structures combining different functional segments - hydrophobic arms for viscosity modification and hydrophilic cores for stability. This composite approach enables simultaneous achievement of high viscosity and shear stability by integrating complementary properties in a single molecular architecture.
2Reliability
If additional amounts of lower molecular weight viscosity modifier are added, then shear stability improves, but low temperature viscometrics deteriorate
Solution Approach 1:
The star polymer is designed to perform multiple functions simultaneously: the central core provides shear stability while the radiating arms maintain viscosity and low-temperature flow characteristics. This multi-functionality eliminates the need to add separate components, preventing the deterioration of low-temperature viscometrics that occurs when lower molecular weight modifiers are added in excess.
3Ease of manufacture
If conventional polymerisation processes are used, then polymer production is simple, but polydispersity is high
Solution Approach 1:
The patent introduces a chain transfer agent as an intermediary substance that mediates the polymerisation process. This agent controls the growth of polymer chains by transferring active centers, thereby reducing polydispersity while maintaining the simplicity of free radical polymerisation. The chain transfer agent acts as a mediator between the initiator and monomers, enabling precise molecular weight control without complex process changes.
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 process results in polymers with enhanced low and high temperature viscometrics, shear stability, and dispersant/viscosity modifying properties, allowing for the creation of effective lubricating compositions with improved performance characteristics.
Implementation Method 1
The process involves controlled radical polymerization using a chain transfer agent with a thiocarbonyl thio group and a free radical leaving group
Implementation Method 2
contacting: (i) a free radical initiator; (ii) a chain transfer agent containing a thiocarbonyl thio group and a free radical leaving group; and (iii) a radically polymerisable monomer, to form a polymer chain
Implementation Method 3
contacting the polymer of step (1) with a polyvalent coupling agent to form a star-polymer
Data Source
AI summary
The present invention provides a process for preparing a polymer, employing the steps of: (1) contacting a free radical initiator; a chain transfer agent containing a thiocarbonyl thio group and a free radical leaving group; and a radically polymerisable monomer, to form a polymer chain; and (2) contacting the polymer chain of step (1) with at least one of a polyvalent coupling agent, a polymerization inhibitor, a grafting acylating agent, an amine and an oil of lubricating viscosity. The invention further provides compositions and uses for the polymer.