Bio-Based Superabsorbent Polymer Crosslinking at Mild Temperatures

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Solution Overview

Problem

Existing superabsorbent polymers (SAPs) are predominantly petroleum-based and non-degradable, requiring high-temperature crosslinking processes, which are energy-intensive and environmentally unsustainable.

Innovation Solution

A bio-based and biodegradable SAP formulation using sodium alginate, modified cellulose, activation agents, crosslinking agents, and pH-adjusting agents, processed at temperatures below 80°C to achieve high bio-content and biodegradability, meeting international biodegradation standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If petroleum-based polyacrylate is used as SAP material, then absorption performance is achieved, but environmental sustainability and biodegradability deteriorate

Engineering Contradiction:

Improveabsorption performanceVSAvoidenvironmental pollution

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by replacing petroleum-based polyacrylate with bio-based polysaccharide polymers (carboxymethyl cellulose, starch, chitosan) that maintain absorption functionality while eliminating environmental harm. This parameter substitution resolves the contradiction between absorption performance and environmental sustainability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite SAP materials by combining multiple bio-based polysaccharide polymers (e.g., carboxymethyl cellulose, starch, chitosan) in specific ratios to achieve both high absorption performance and biodegradability. This composite approach allows optimization of both functional and environmental properties simultaneously.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If high-temperature crosslinking processes are used, then SAP network structure is formed, but energy consumption increases

Engineering Contradiction:

Improvecrosslinking network structureVSAvoidenergy consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The patent changes the temperature parameter from high-temperature crosslinking (80-140°C) to mild temperature conditions (room temperature or slightly elevated), thereby reducing energy consumption while still achieving effective crosslinking network formation through bio-based crosslinking mechanisms.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces thermal energy-driven crosslinking with chemical or enzymatic crosslinking mechanisms inherent to bio-based polymers, eliminating the need for high-temperature processing and significantly reducing energy consumption while maintaining network structure stability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Stability of the object's composition

If conventional crosslinking agents are used, then SAP crosslinking is achieved, but biodegradability deteriorates

Engineering Contradiction:

ImprovecrosslinkingVSAvoidbiodegradability

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical nature of crosslinking agents from conventional synthetic compounds to bio-based or natural crosslinking agents that are compatible with polysaccharide polymers, enabling crosslinking while maintaining biodegradability through natural decomposition pathways.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs crosslinking agents that are themselves biodegradable and environmentally benign, allowing the entire SAP system to be disposed of or decomposed after use without environmental harm, aligning with the disposable nature of many SAP applications.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 SAP exhibits high bio-content, biodegradability, and safety, with properties suitable for disposable hygiene products, aligning with eco-friendly market demands and reducing environmental impact.

Implementation Method 1

sodium alginate (SA), modified cellulose

Methodology Applied

Scientific EffectHydrogen bonding:

Implementation Method 2

water-absorbing hydrophilic and crosslinked polymer

Methodology Applied

Scientific EffectHydrophilic interaction: Hydrophile

Implementation Method 3

crosslinking reactions at temperatures below 80° C.

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentUS20250360488A1Bio-based and bio-degradable superabsorbent polymer and methods for preparing the same

Publication Date: 2025.11.27 HONG KONG APPLIED SCI & TECH RES INST

AI summary

The present invention relates to a bio-based and biodegradable superabsorbent polymer (SAP) comprising sodium alginate, modified cellulose, at least one activation agent, and at least one crosslinking agent. The SAP exhibits a high bio-based content of up to 93% and fulfills industrial composting standards such as EN 13432. The crosslinking reactions are performed under mild conditions, including ambient temperatures and neutral to alkaline pH, eliminating the need for high thermal energy. The resulting SAP granules demonstrate excellent liquid absorption performance, rapid swelling, high retention, and no observed toxicity or skin sensitization. The invention provides a sustainable alternative to petroleum-based SAPs for use in hygiene products, agriculture, and other disposable applications.