Segmented Acrylic Copolymers for Adhesive Processability
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Solution Overview
Problem
Current acrylic polymers face challenges in achieving optimal viscoelastic properties and processability due to high molecular weights and the need for high crosslinking, which can result in defects and energy-intensive solvent removal processes, while also requiring high processing temperatures and multiple steps for telechelic polymer production.
Innovation Solution
The development of acrylic polymers with controlled placement of crosslinkable monomers into specific segments of the polymer backbone using controlled radical polymerization techniques, allowing for tailored properties and reduced molecular weight, thereby achieving low viscosity and high solids solutions with improved processability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high molecular weight acrylic copolymers are used to achieve high performance, then strength and crosslinking are improved, but viscosity increases and processability deteriorates
Solution Approach 1:
The polymer is segmented into distinct blocks: soft segments (from crosslinkable monomers like cyclic carbonates) and hard segments (from non-crosslinkable monomers). This segmentation allows the soft segments to provide crosslinking sites for strength while the overall architecture maintains lower viscosity and better processability compared to high molecular weight linear polymers.
Solution Approach 2:
Crosslinkable functional groups are locally concentrated in the soft segments rather than being uniformly distributed throughout the entire polymer chain. This local concentration allows crosslinking to occur in specific regions, providing strength where needed while leaving other regions more flexible and processable.
2Strength
If high crosslinking is used to achieve high performance, then strength is improved, but defects increase and energy consumption increases
Solution Approach 1:
Crosslinking is confined to the soft segments containing crosslinkable monomers, rather than occurring throughout the entire polymer. This segmented crosslinking approach prevents excessive crosslinking that would cause defects, while still achieving sufficient strength through controlled crosslink density in the appropriate regions.
3Strength
If high crosslinking is used to achieve high performance, then strength is improved, but energy consumption increases
Solution Approach 1:
The segmented architecture allows crosslinking to occur in discrete soft segments rather than requiring high crosslinking throughout the entire polymer. This reduces the total energy input needed for crosslinking while maintaining strength, as crosslinking is concentrated where most effective.
4Strength
If telechelic polymers are used to achieve high strength, then strength is improved, but production complexity increases
Solution Approach 1:
The patent combines the functions of telechelic polymers (end-group crosslinking) with block copolymer architecture in a single synthesis step using controlled radical polymerization. This merging eliminates the need for separate telechelic polymer production steps while maintaining the strength benefits of end-group functionality and adding the advantage of controlled block architecture.
Solution Approach 2:
The controlled radical polymerization methodology establishes the block copolymer architecture with crosslinkable groups in place during the initial polymerization step, rather than requiring subsequent modification steps. This preliminary action simplifies production by integrating multiple functions into the primary synthesis step.
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 high-performance elastomers and adhesives with controlled crosslink density, preserving polymer chain ends and avoiding heterogeneity, resulting in enhanced viscoelastic and surface properties without the need for high processing temperatures or excessive solvent use.
Implementation Method 1
controlled radical polymerization techniques have been developed to afford good architectural control of (meth)acrylic monomers
Implementation Method 2
State of the art (meth)acrylic copolymers meet many performance characteristics by virtue of their high molecular weight and crosslinking reactions
Data Source
AI summary
Acrylic copolymers that include the controlled placement of particular functional groups within the polymer structure are provided. The copolymers contain at least two reactive segments and are manufactured via a controlled radical polymerization process. The copolymers are useful in the manufacture of adhesives and elastomers.