Carboxylate-Functionalized Cellulose Microspheres for Biodegradable Thermal Expansion

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Solution Overview

Problem

Existing thermally expandable microspheres are not derived from sustainable sources and are often non-biodegradable, leading to environmental concerns due to their slow biodegradation and potential cumulative build-up.

Innovation Solution

Development of thermally expandable microspheres with a polymeric shell made from carboxylate-functionalised cellulose, which has a glass transition temperature (Tg) of at least 125° C, providing a sustainable and biodegradable alternative.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If thermoplastic polymers (acrylates, acrylonitriles, acrylamides, vinylidene dichloride, styrenes) are used in microspheres, then effective thermal expansion properties are achieved, but sustainability and biodegradability deteriorate due to petrochemical sources and environmental accumulation

Engineering Contradiction:

Improveenvironmental harmVSAvoidthermal expansion performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent changes the chemical composition parameter of the polymeric shell from conventional thermoplastics to carboxylate-functionalised cellulose, which has a glass transition temperature of at least 125°C. This parameter change enables the material to achieve thermal expansion performance while being derived from sustainable sources and biodegradable, thus resolving the contradiction between environmental harm and thermal expansion performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses carboxylate-functionalised cellulose as a biopolymer composite material that combines the structural properties needed for thermal expansion with sustainable and biodegradable characteristics. This composite approach allows the microsphere to maintain effective thermal expansion while addressing environmental concerns associated with conventional petrochemical-based thermoplastics

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If carboxylate-functionalised cellulose with Tg of at least 125°C is used in the polymeric shell, then sustainability and biodegradability are improved, but manufacturing complexity increases

Engineering Contradiction:

Improveenvironmental harmVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent employs preliminary action by pre-forming the carboxylate-functionalised cellulose polymer in a suitable solvent before incorporating it into the microsphere structure. This preliminary preparation simplifies the overall manufacturing process by allowing the polymer to be ready for use in the emulsion or suspension polymerization step, thus reducing manufacturing complexity while maintaining sustainability benefits

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses a suitable solvent as an intermediary medium to dissolve or disperse the carboxylate-functionalised cellulose polymer before forming the polymeric shell. This intermediary approach simplifies manufacturing by enabling easy handling and processing of the biopolymer, reducing the complexity associated with working with sustainable materials

Inventive Principle:

Principle #24Intermediary (Mediator)

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 use of carboxylate-functionalised cellulose in thermally expandable microspheres addresses environmental concerns by offering a sustainable and biodegradable solution, while maintaining effective thermal expansion properties.

Implementation Method 1

the blowing agent vapourises and expands, thus expanding the microsphere

Methodology Applied

Scientific EffectVapourisation: Evaporation

Implementation Method 2

the microsphere diameter can increase between about 1.5 and 8 times during expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

the thermoplastic polymeric shell softens

Methodology Applied

Scientific EffectSoftening: Melting

Data Source

PatentUS12338336B2Thermally expandable cellulose-based microspheres

Publication Date: 2025.06.24 AKZO NOBEL CHEMICALS INTERNATIONAL BV

AI summary

The disclosure relates to thermally expandable microspheres comprising a polymeric shell surrounding a blowing agent-containing hollow core, the polymer shell comprising a carboxylate-functionalised cellulose having a glass transition temperature (Tg) of at least about 125° C. The disclosure also relates to a method for preparing such thermally expandable microspheres, comprising mixing an aqueous phase that optionally comprises an emulsifier with an organic phase that comprises an organic solvent, a blowing agent and a carboxylate-functionalised cellulose having a Tg of at about least 125° C., to form a microsphere dispersion.