RAFT Polymerization for Surfactant-Free Latex Particle Synthesis
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Solution Overview
Problem
Current methods for aqueous dispersion polymerization struggle to produce colloidally stable latex particles with small sizes without using surfactants, which can compromise the quality of waterborne coatings due to surfactant migration and adhesion issues.
Innovation Solution
The method employs RAFT polymerization under aqueous conditions using a macromonomer chain transfer agent and a vinyl monomer to form block copolymers, allowing for the synthesis of sterically-stabilized nanolatexes and vesicles with controlled sizes and morphologies without the need for surfactants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If emulsion polymerisation is used to reduce latex particle size, then smaller particle sizes are achieved, but surfactant migration occurs compromising coating quality
Solution Approach 1:
The invention extracts and eliminates the harmful surfactant component from the polymerisation system by using conventional free radical polymerisation without surfactants, achieving small particle sizes through alternative stabilisation mechanisms that prevent surfactant-related coating defects
Solution Approach 2:
The invention introduces polymer stabilisers as intermediary substances that mediate between the polymer particles and aqueous medium, providing steric stabilisation without the harmful effects of surfactant migration, thus enabling small particle sizes while maintaining coating quality
2Reliability
If conventional free radical polymerisation is used without surfactants, then coating quality is maintained, but control over particle size and polydispersity is limited
Solution Approach 1:
The invention changes the stabilisation mechanism parameter from electrostatic (surfactant-based) to steric stabilisation (polymer-based), enabling precise control over particle size and polydispersity while maintaining coating quality through the use of polymer stabilisers with controlled molecular weights and architectures
3Manufacturing precision
If RAFT polymerisation is used under aqueous conditions, then particles of low polydispersity are produced, but the process complexity increases
Solution Approach 1:
The invention employs self-stabilisation mechanisms where the block copolymers formed through RAFT polymerisation automatically provide steric stabilisation to the particles, eliminating the need for separate stabiliser addition steps and reducing overall process complexity while achieving low polydispersity
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 enables the production of colloidally stable particles with low polydispersity and controlled sizes, from 10 nm to 1500 nm, suitable for various applications including coatings, drug delivery, and biomedical uses, while avoiding surfactant-related issues.
Implementation Method 1
initiating an aqueous dispersion-type radical addition fragmentation chain transfer (RAFT) polymerisation
Implementation Method 2
The resulting particles are stabilised by the P1 block through steric stabilisation
Implementation Method 3
The block copolymer forms sterically-stabilized particles
Data Source
AI summary
A method of preparing a block copolymer of Formula (B) wherein P1 represents a substantially aqueously soluble polymeric component and P2 represents a substantially aqueously insoluble polymeric component, comprises admixing an aqueously soluble polymer macro-chain transfer agent comprising P1 with a monomer (M2) and initiating an aqueous dispersion-type radical addition fragmentation chain transfer (RAFT) polymerization. (P1) is derived from a monomer (M1) selected from monomers of the Formulae (M1A), (M1B) and/or (M1C) where R1, R10 and R11 represent a substituent of (M1A) or (M1C) which allows P1 to be at least partially aqueously soluble, R2 represents H, CH3 or CN, RS represents one or more substituents of the aromatic ring effective to allow P1 to be at least partially aqueously soluble, and monomer M2 is selected from: where R3 is a substituent of (M2) which allows P2 to be substantially aqueously insoluble, and R4 and R6 independently represent H or methyl.