Silane-Functionalized Carboxy-Terminated Polymers for Tire Tread
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Solution Overview
Problem
Existing methods for introducing carboxyl groups at the ends of polymer chains in diene rubbers face challenges such as long reaction times, incomplete conversion of functionalizing reagents, side reactions leading to polymer branching, and the use of toxic gases like CO2 or ethylene oxide, which complicates the process and results in ineffective functionalization.
Innovation Solution
The use of silalactones as functionalizing reagents to produce carboxyl-terminated polymers, which react with reactive ends of polymer chains to form carboxylate groups, avoiding the disadvantages of previous methods by enabling controlled functionalization without the need for toxic gases and minimizing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (CO2, ethylene oxide, cyclic anhydrides) are used to introduce carboxyl groups at polymer chain ends, then functionalization is achieved, but the process requires toxic gases, long reaction times, and causes side reactions like branching
Solution Approach 1:
The patent uses silane compounds as intermediary reagents that first react with the anionic polymer chain ends to form silane-terminated polymers, which then undergo hydrolysis to produce carboxyl groups. This two-step indirect approach avoids direct use of toxic gases like CO2 and ethylene oxide, eliminating the associated safety and environmental hazards while maintaining effective functionalization
Solution Approach 2:
The invention extracts and removes the problematic toxic gas step from the functionalization process entirely. By using silane compounds followed by hydrolysis, the method eliminates the need for CO2, ethylene oxide, and other harmful reagents, achieving carboxyl group introduction without the associated harmful factors
2Reliability
If conventional functionalizing reagents are used, then carboxyl groups are introduced, but reaction times are long and conversion is incomplete
Solution Approach 1:
The patent changes the chemical parameters of the functionalization process by using silane compounds with specific reactivity characteristics. The silane reagents react rapidly with anionic polymer ends under mild conditions, and the subsequent hydrolysis step efficiently produces carboxyl groups with high conversion, dramatically reducing both reaction time and improving completeness compared to conventional methods
3Reliability
If conventional methods are used for end group functionalization, then carboxyl groups are introduced, but polymer branching occurs as a side reaction
Solution Approach 1:
The silane compound acts as an intermediary that reacts selectively with the anionic polymer chain ends through silicon-carbon bond formation. This controlled reaction pathway, followed by hydrolysis to generate carboxyl groups, prevents unwanted side reactions like polymer branching that occur with conventional reagents, thereby maintaining polymer structure integrity
Solution Approach 2:
The invention extracts and eliminates the branching side reaction problem by removing the conventional functionalizing reagents that cause it. The silane-based approach provides a clean reaction pathway that introduces carboxyl groups without causing polymer structure degradation or branching
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 results in polymers with improved dynamic-mechanical properties, specifically enhancing wet skid resistance and rolling resistance in tire treads while maintaining high abrasion resistance, as demonstrated by the synthesis of styrene-butadiene copolymers with reduced cold flow and increased Mooney viscosity.
Implementation Method 1
The use of silalactones as functionalizing reagents to produce carboxyl-terminated polymers, which react with reactive ends of polymer chains to form carboxylate groups
Implementation Method 2
The introduction of functional groups at the end of the polymer chains and/or start of the polymer chains enables physical or chemical attachment of these ends and/or starts of the polymer chains to the filler surface
Data Source
AI summary
Polymers are functionalized at chain ends thereof with silane-containing carboxyl groups of the formula (I)where R1 and R2 are the same or different and are each an H, alkyl, alkoxy, cycloalkyl, cycloalkoxy, aryl, aryloxy, alkaryl, alkaryloxy, aralkyl or aralkoxy radical; R3 and R4 are the same or different and are each an H, alkyl, cycloalkyl, aryl, alkaryl or aralkyl radical; and A is a divalent organic radical.