Hydrolysable Polyacrylate Microcapsule Shell for Controlled Degradation
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Solution Overview
Problem
Existing microcapsules either fail to effectively contain core materials or persist excessively in environments, lacking the ability to fracture and degrade over time as needed for various applications, especially in sensitive environments.
Innovation Solution
Incorporating acid hydrolysable groups into a polyacrylate polymer during encapsulation, modifying the polymer shell to increase hydrophilicity and enhance degradability, allowing the capsules to be stable initially but susceptible to degradation post-use, particularly in wet or acidic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microcapsule processes are used, then containment of core materials is achieved, but the microcapsules persist excessively in environments without degrading
Solution Approach 1:
The patent modifies the polymer shell composition by incorporating acid-hydrolyzable groups (such as ester groups) into the polyacrylate structure. This changes the chemical parameters of the shell material, enabling it to undergo hydrolysis and depolymerization in acidic or enzymatic environments, thereby transforming the capsule from environmentally persistent to biodegradable while maintaining containment effectiveness during use
Solution Approach 2:
The invention creates a composite polymer shell structure combining polyacrylate with acid-hydrolyzable functional groups. This composite material integrates both the desirable containment properties of polyacrylate and the degradability characteristics of hydrolyzable groups, resolving the contradiction between durability and environmental persistence
2Duration of action of stationary object
If the polymer shell is made degradable by incorporating hydrolysable groups, then environmental persistence is reduced, but containment stability may be compromised
Solution Approach 1:
The patent introduces acid-hydrolyzable groups at specific locations within the polymer shell structure rather than throughout the entire molecule. This localized modification allows the shell to maintain structural integrity and containment stability under normal conditions while possessing specific sites that can undergo hydrolysis and degradation when exposed to acidic or enzymatic environments, thus resolving the contradiction between stability and degradability
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 modified microcapsules achieve robust containment while ensuring degradation after use, reducing persistence in environments and enhancing their suitability for diverse applications by facilitating hydrolysis and depolymerization.
Implementation Method 1
activating the initiator or initiators by heat or actinic radiation to react the monomers forming a polymeric shell surrounding the droplets of the emulsion
Implementation Method 2
Incorporating acid hydrolysable groups into a polyacrylate polymer during encapsulation, modifying the polymer shell to increase hydrophilicity and enhance degradability, allowing the capsules to be stable initially but susceptible to degradation post-use, particularly in wet or acidic conditions
Data Source
AI summary
The invention describes a core shell microcapsule wherein the capsule shell is hydrolysable. The capsule is made from a water phase with initiator and emulsifier, and from one or more oil phases having a first multifunctional (meth)acrylate monomer having greater than one ester group on average in the monomer and having a hydrophilicity index of less than 20; a second multifunctional (meth)acrylate monomer, the second multifunctional (meth)acrylate comprising a hydrophilic multifunctional polar monomer having a hydrophilicity index of at least 20 and said second multifunctional polar monomer comprising 50% or less of the capsule shell along with an acidic (meth)acrylate monomer or at least one oil soluble or dispersible simple acid, the acidic (meth)acrylate monomer having one or more groups which are selected from carboxy and sulfonic groups, and optionally from 0 to 50% by weight of the shell comprises in addition an aliphatic polyester comprising an oligomer, polymer or co-polymer of one or more of lactic acid, caprolactone, or glycolic acid, the aliphatic polyester having two or more of acrylate or methacrylate groups.