Crosslinked Poly(allylamine) Polymer Stability and Purity
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Solution Overview
Problem
Crosslinked poly(allylamine) polymers prepared using traditional methods often suffer from poor compositional homogeneity and the presence of undesirable process-related impurities, such as allylamine or its derivatives, due to incomplete incorporation of crosslinkers, leading to stability issues during storage and use.
Innovation Solution
A process involving concurrent polymerization and crosslinking of monoallylamine and multiallylamine in the presence of a radical initiator, acid, and surfactant, followed by further crosslinking with a swelling agent, to minimize unreacted allyl groups and improve the purity and stability of the polymer, with less than 2.5% sp2 allyl carbons and a swelling ratio of less than 2, is employed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional crosslinking methods using epichlorohydrin are used, then the polymer can be prepared, but poor compositional homogeneity and process-related impurities are generated
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking process by using alternative crosslinking agents (diallylamine, multiallylamine) with different reactivity characteristics compared to epichlorohydrin. This parameter change results in improved compositional homogeneity and reduced formation of process-related impurities such as allylamine derivatives, while maintaining the desired crosslinked polymer structure.
2Productivity
If diallylamine crosslinker is used to improve polymerization efficiency, then crosslinking is enhanced, but unincorporated crosslinker leads to stability issues
Solution Approach 1:
The patent employs multiallylamine crosslinkers with multiple reactive allyl groups (two or more per molecule). This allows for partial incorporation of the crosslinker into the polymer network while maintaining sufficient crosslinking density. The excess unreacted allyl groups are minimized through optimized feed ratios, achieving a balance between polymerization efficiency and storage stability by reducing free unincorporated crosslinker that could degrade during storage.
3Strength
If crosslinking density is increased to improve structural integrity, then mechanical strength is enhanced, but swelling ratio increases
Solution Approach 1:
The patent optimizes the crosslinking parameters by controlling the feed ratio of multiallylamine crosslinker and using crosslinkers with different molecular structures (diallylamine vs. multiallylamine with varying numbers of allyl groups). This parameter optimization achieves adequate structural integrity for pharmaceutical application while limiting excessive swelling ratio to below 2.0, balancing mechanical strength and volume 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 approach results in a crosslinked poly(allylamine) polymer with enhanced stability and purity, reducing allylamine formation and improving therapeutic efficacy by maintaining clinical significance in acid-base disorders through effective ion binding.
Implementation Method 1
concurrent polymerization and crosslinking of monoallylamine and multiallylamine in the presence of a radical initiator
Implementation Method 2
effective ion binding
Data Source
AI summary
Pharmaceutical compositions for and methods of treating an animal, including a human, and methods of preparing such compositions. The pharmaceutical compositions contain crosslinked amine polymers and may be used, for example, to treat diseases or other metabolic conditions in which removal of a target species from the gastrointestinal tract would provide physiological benefits.