Reactive Stabilizer Halogenated Vinyl Polymerization
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Solution Overview
Problem
Existing dispersed-phase polymerization processes are limited in their ability to effectively polymerize a wide range of hydrophobic monomers, particularly halogenated vinyl compounds, and often require toxic fluorinated surfactants, which have environmental concerns.
Innovation Solution
A novel dispersed-phase polymerization process using a reactive stabilizer with a polymer chain derived from RAFT or MADIX controlled radical polymerization of N-(vinyllactam) monomers, incorporating a thiocarbonylthio group, which allows for the polymerization of halogenated vinyl compounds without additional surfactants, replacing them with less toxic fluorinated or chlorinated reactive stabilizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fluorinated surfactants are used to stabilize dispersed phase polymerization, then emulsion stability is improved, but toxicity and environmental harm increase
Solution Approach 1:
The invention changes the chemical composition parameters of the surfactant system by using reactive stabilizers containing thiocarbonylthio groups (RAFT or MADIX agents) instead of conventional fluorinated surfactants. This substitution maintains emulsion stability while eliminating the toxicity associated with fluorinated compounds, directly resolving the contradiction between stability and harmful factors.
Solution Approach 2:
The reactive stabilizer acts as an intermediary substance that performs the dual function of emulsion stabilization and polymerization control. The thiocarbonylthio-containing compound mediates between the dispersed monomer droplets and the continuous phase, providing stabilization without the harmful effects of traditional surfactants, thus resolving the toxicity-stability contradiction.
2Productivity
If conventional surfactants are used in dispersed phase polymerization, then polymerization efficiency is improved, but product purity and surfactant-free latices deteriorate
Solution Approach 1:
The reactive stabilizer performs self-service by simultaneously acting as both emulsion stabilizer and polymerization initiator/control agent. The thiocarbonylthio group in the stabilizer participates in the polymerization reaction, eliminating the need for separate surfactant and initiator systems, thereby achieving both high productivity and product purity without residual surfactant contamination.
Solution Approach 2:
The invention merges the functions of surfactant and polymerization initiator into a single reactive stabilizer molecule. The thiocarbonylthio-containing compound combines emulsification properties with controlled radical polymerization capability, achieving synergistic effects that improve both polymerization efficiency and product purity simultaneously.
3Stability of the object's composition
If additional surfactants are used to stabilize dispersed phase, then emulsion stability is improved, but device complexity and process complexity increase
Solution Approach 1:
The reactive stabilizer exhibits multi-functionality by simultaneously providing emulsion stabilization, polymerization initiation, and polymerization control functions. This single compound replaces multiple separate additives (surfactants and initiators), simplifying the overall process while maintaining emulsion stability throughout the polymerization reaction.
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 process enables the production of surfactant-free or low-surfactant latices of halogenated polymers with controlled polymerization and particle size, reducing toxicity and environmental impact while achieving efficient polymerization of halogenated vinyl compounds.
Implementation Method 1
a reactive stabilizer comprising a polymer chain including (or even consisting of) N-(vinyllactam) monomer units and a thiocarbonylthio group —S(C═S)—
Implementation Method 2
They act, secondly, as polymerization control agent, typically via reversible addition-fragmentation transfer processes
Implementation Method 3
at least one source of free radicals
Implementation Method 4
in which the polymer chains have a 'living' nature, in the sense that each step of incorporation of a monomer unit into the chain
Implementation Method 5
such molecules being of hydrophilic or amphiphilic nature typically comprising a hydrophilic polymer chain
Implementation Method 6
These reactive stabilizers ensure, firstly, the stabilization of the emulsion of droplets of the dispersed phase due to their hydrophilic nature
Data Source
AI summary
The present invention concerns a method for the dispersed phase polymerization of halogenated vinyl compounds, having the formula RbRcC═CX1X2, where: X1═F or CI, X2═H, F or CI, each of Rb and Rc, separately represents: —H, CI, F; or—an alkyl group, preferably chlorinated and/or fluorinated, and more advantageously perchlorinated or perfluorinated, comprising a step (E1) wherein said monomers are introduced into an aqueous phase together with—at least one source of free radicals; and—at least one reactive stabilizer comprising a polymer chain and a thiocarbonylthio-S group (C═S)—, said polymer chain comprising non-(N vinyl lactam)monomer units.