Block Copolymer Composition for Absorbent Gels With Biodegradability
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Solution Overview
Problem
Existing superabsorbent resins are insoluble in water and poorly biodegradable, leading to environmental pollution, while block copolymers with polyvinyl alcohol and polyacrylic acid blocks lack sufficient water absorbency and shape retention.
Innovation Solution
A block copolymer comprising a vinyl alcohol-based polymer block and an ionic polymer block with carboxylic acid groups, produced through controlled radical polymerization and saponification, ensuring high water absorbency, solubility, and gel shape retentivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional superabsorbent resins are used, then water absorbency is achieved, but biodegradability and water solubility are insufficient
Solution Approach 1:
The invention uses a block copolymer composite structure combining polyvinyl alcohol blocks (providing biodegradability and water solubility) with polyacrylic acid blocks (providing water absorbency). This composite material simultaneously achieves high water absorbency while maintaining biodegradability and water solubility, resolving the contradiction between absorbency and environmental harm.
2Quantity of substance
If crosslinked polymers are used, then water absorbency is improved, but water solubility and biodegradability deteriorate
Solution Approach 1:
The invention changes the structural parameters of the polymer by using a block copolymer architecture with specific molecular weight ratios (Mnb/MnA from 0.1 to 0.9) and ionic group contents (5-95 mol%), rather than crosslinked structures. This parameter optimization enables the polymer to maintain water solubility and biodegradability while achieving sufficient water absorbency through ionic interactions rather than covalent crosslinks.
3Stability of the object's composition
If block copolymer structure is adopted, then water solubility and biodegradability are improved, but water absorbency and shape retention are insufficient
Solution Approach 1:
The invention applies local quality by creating distinct blocks with different functions: polyvinyl alcohol blocks provide water solubility and biodegradability, while polyacrylic acid blocks provide water absorbency and gel shape retentivity. The specific composition ranges (Mnb from 15,000 to 220,000, Mnc from 20,000 to 220,000, and Mnb/MnA ratio from 0.1 to 0.9) optimize the local properties of each block to achieve overall performance balance.
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 block copolymer achieves high absorbency of water and salt water with gel shape retentivity and solubility, suitable for use in absorbers and absorbent articles.
Implementation Method 1
an ionic polymer block (c) containing a monomer unit with an ionic group forming a salt
Implementation Method 2
these polymers are not sufficiently biodegradable and have a risk of causing soil pollution, marine pollution
Data Source
AI summary
A block copolymer (A) including a vinyl alcohol-based polymer block (b) and an ionic polymer block (c) containing a monomer unit with an ionic group forming a salt and a vinyl alcohol-based monomer unit. The ionic group is a carboxylic acid group, a sulfonic acid group, or an ammonium group. The vinyl alcohol-based polymer block (b) has a number-average molecular weight (Mnb) from 15,000 to 220,000. The ionic polymer block (c) has a content of the vinyl alcohol-based monomer unit from 5 to 95 mol % based on the total monomer units. The block copolymer (A) has a number-average molecular weight (MnA) from 20,000 to 440,000. A ratio (Mnb/MnA) of the number-average molecular weight (Mnb) to the number-average molecular weight (MnA) is from 0.1 to 0.9.