Functionalized Nitrile Rubber via Metathesis Catalyst
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Solution Overview
Problem
Current methods fail to simultaneously achieve molecular weight reduction and functionalization of nitrile rubbers through metathesis, lacking specific catalysts and olefins for efficient degradation and functionalization.
Innovation Solution
A process involving metathesis catalysts based on transition metals from group 6 or 8 with carbenically attached ligands, using functionalized olefins of specific structures to reduce the molecular weight of nitrile rubbers while introducing corresponding functional groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional metathesis catalysts (groups 5-7) are used for polymer degradation, then degradation can occur, but the process requires environmentally harmful co-catalysts (tin tetraalkyls, germanium/tin/lead halides) and cannot effectively degrade nitrile rubbers
Solution Approach 1:
The invention extracts and eliminates the harmful co-catalyst requirement from the metathesis process by using catalysts from groups 6 and 8 that can perform both degradation and functionalization without requiring tin tetraalkyls or germanium/tin/lead halides as co-catalysts
Solution Approach 2:
The invention changes the catalyst selection parameter from transition metal groups 5-7 to groups 6 and 8, which fundamentally alters the catalytic mechanism to eliminate the need for harmful co-catalysts while enabling effective nitrile rubber degradation
2Quantity of substance
If metathesis degradation is performed to reduce molecular weight, then molecular weight reduction is achieved, but functionalization of the polymer chains does not occur simultaneously
Solution Approach 1:
The invention merges two separate processes (metathesis degradation and functionalization) into a single simultaneous reaction step, where the polymer chains are degraded and functional groups are introduced in one operation using the same catalyst system
Solution Approach 2:
The metathesis catalysts from groups 6 and 8 exhibit multi-functionality by simultaneously performing degradation (breaking polymer chains) and functionalization (introducing functional groups from olefins), eliminating the need for separate processing steps
3Productivity
If conventional metathesis processes are used, then degradation occurs, but the process lacks efficiency and specificity for nitrile rubber functionalization
Solution Approach 1:
The invention uses functionalized olefins as intermediaries that mediate both the degradation and functionalization processes, where the olefin molecules serve as building blocks that incorporate functional groups into the degraded polymer chains in a controlled manner
Solution Approach 2:
The invention changes the chemical specificity parameter by selecting catalysts from groups 6 and 8 that are particularly effective for nitrile rubber, and by selecting appropriate functionalized olefins, thereby achieving both high degradation efficiency and precise functionalization control
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 effectively reduces the molecular weight of nitrile rubbers and incorporates functional groups, achieving a weight-average molecular weight ratio of less than 55% of the initial nitrile rubber, enabling the production of functionalized nitrile rubbers with improved properties.
Implementation Method 1
Metathesis reactions are used extensively as part of chemical syntheses, for example in ring-closing metatheses (RCM), cross-metatheses (CM), ring-opening metatheses (ROM), ring-opening metathesis polymerizations (ROMP), acyclic diene metathesis polymerizations (ADMET)
Implementation Method 2
a metathesis catalyst which is a complex catalyst based on a metal from transition group 6 or 8 of the Periodic Table which has at least one ligand attached carbenically to the metal
Data Source
AI summary
Provided are new functionalized nitrile rubbers, which may optionally also be in partially or wholly hydrogenated form, and also a process for preparing them by metathesis of nitrile rubbers in the presence of a metathesis catalyst and at least one functionalized allyl compound. The new functionalized nitrile rubbers are suitable for producing vulcanizable mixtures and allow the production of vulcanizates having very stable networks. Also made possible, in particular, is the synthesis of block copolymers.