Aqueous Polymer Dispersion for pH-Dependent Solubility
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Solution Overview
Problem
Existing processes for preparing pharmaceutical coatings lack ease of preparation and often require elaborate drying or finishing steps, and existing polymers do not adequately provide pH-dependent solubility, water vapor barrier properties, or effective taste masking for active ingredients.
Innovation Solution
Aqueous polymer dispersions are prepared by free-radical emulsion polymerization of a monomer mixture comprising N,N-diethylaminoethyl methacrylate and esters of α,β-ethylenically unsaturated mono- and dicarboxylic acids in an aqueous medium at a pH of at least 8, allowing for the formation of polymer films with pH-dependent solubility and improved barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solution polymerization in organic solvent is used, then polymer coatings can be prepared, but the preparation process becomes complex and requires elaborate drying or finishing steps
Solution Approach 1:
The invention changes the polymerization medium from organic solvent to aqueous medium, and maintains polymerization at pH ≥ 8 throughout the process. This parameter change eliminates the need for elaborate drying or finishing steps while simplifying the overall preparation process, directly resolving the contradiction between ease of manufacture and process complexity
Solution Approach 2:
The invention uses aqueous polymer dispersions as a substitute for traditional organic solvent-based polymer coatings. The aqueous dispersion can be directly applied and forms functional coatings without requiring the complex drying and finishing steps needed for organic solvent systems, thereby simplifying the manufacturing process
2Adaptability or versatility
If copolymers based on N,N-dialkylaminoalkyl(meth)acrylates are used, then pH-dependent solubility is achieved, but the ester group is prone to hydrolysis in basic medium
Solution Approach 1:
The invention uses composite copolymer structures combining N,N-diethylaminoethyl methacrylate with hydrophobic monomers (esters of α,β-ethylenically unsaturated mono- and dicarboxylic acids). This composite approach provides both pH-dependent solubility through the amino group and enhanced chemical stability by incorporating hydrolysis-resistant ester groups, resolving the contradiction between adaptability and reliability
Solution Approach 2:
The invention localizes the pH-responsive functionality specifically to the N,N-diethylaminoethyl methacrylate units while the hydrophobic comonomer units provide structural stability and resistance to hydrolysis. This local quality differentiation allows the polymer to exhibit pH-dependent solubility without sacrificing chemical stability in basic medium
3Adaptability or versatility
If polymer films with pH-dependent solubility are used, then taste masking and controlled release are improved, but water vapor barrier properties are insufficient
Solution Approach 1:
The invention creates composite copolymer films combining N,N-diethylaminoethyl methacrylate units (providing pH-dependent solubility for taste masking and controlled release) with hydrophobic ester comonomer units (providing water vapor barrier properties). This composite structure simultaneously achieves pH-responsive functionality and effective water vapor protection, resolving the contradiction between adaptability and harmful factor resistance
Solution Approach 2:
The invention assigns different local functions to different polymer units: the N,N-diethylaminoethyl methacrylate units provide pH-dependent solubility for taste masking and controlled release, while the hydrophobic comonomer units locally provide water vapor barrier properties. This functional differentiation within the polymer structure resolves the contradiction between pH-responsive adaptability and water vapor protection
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 resulting polymer films exhibit excellent pH-dependent solubility, water vapor barrier properties, and effective taste masking, enabling stable and rapid release of active ingredients while maintaining stability and flexibility, even in acidic environments.
Implementation Method 1
free-radical emulsion polymerization of a monomer mixture which comprises N,N-diethylaminoethyl methacrylate
Implementation Method 2
applied in the form of a film, for example by casting, spreading or spraying, and subsequent drying or gelation
Data Source
AI summary
The present invention relates to a process for preparing an aqueous polymer dispersion by free-radical emulsion polymerization of a monomer mixture which comprises N,N-diethylaminoethyl methacrylate, to the polymer dispersion obtainable by this process, and to the use thereof.