Adaptive Copolymer Composition for Stable Cloud Point Control
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Solution Overview
Problem
Existing smart hydrogels, such as PNIPAM polymers, are fragile and their cloud point behavior is sensitive to additives like salts, solvents, and pH, leading to formulation difficulties and limited application versatility.
Innovation Solution
The Adaptive Polymer System (APS) allows for precise control over material properties by adjusting the ratios of polymeric constituents, rather than the constituents themselves, enabling formulation of stimulus-responsive polymers that are adaptable to various ingredients and environmental triggers without compromise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PNIPAM hydrogel concentration is increased to improve cohesiveness and viscosity, then the material becomes more solid-like, but the material becomes more fragile and limited in application
Solution Approach 1:
The patent applies parameter changes by modifying the polymer composition parameters (monomer ratios, molecular weight, architecture) to achieve optimal balance between cohesiveness and flexibility. Specifically, it uses copolymers with controlled monomer compositions (e.g., NIPAM with functional monomers at specific ratios) and adjusts polymer concentration and molecular weight to achieve the desired mechanical properties without excessive fragility.
Solution Approach 2:
The patent employs composite materials by creating copolymer systems combining NIPAM with functional monomers (such as hydrophilic monomers, crosslinking monomers, or monomers with specific functional groups). This composite approach allows the material to inherit the thermoresponsive behavior of NIPAM while gaining improved mechanical strength and flexibility from the complementary monomer components.
2Strength
If binary copolymers with secondary monomers are used to strengthen hydrogels, then mechanical strength improves, but the cloud point transitions below the utility point for certain applications
Solution Approach 1:
The patent uses parameter changes by precisely controlling the monomer composition parameters in the copolymer formulation. It adjusts the ratio of NIPAM to functional monomers, selects specific monomer types with different cloud point effects, and optimizes the overall polymer concentration to achieve a balance where the hydrogel is sufficiently strong while maintaining a cloud point above the required application temperature.
Solution Approach 2:
The patent applies local quality by incorporating specific functional monomers at targeted positions or concentrations within the polymer structure. Different segments of the polymer chain can have different local properties - some regions providing strength while others maintaining appropriate cloud point behavior - achieved through controlled copolymerization and monomer sequencing.
3Stability of the object's composition
If additional solvents like alcohols are included to promote homogenization and material stability, then formulation stability improves, but the cloud point is lowered due to co-solvent effect
Solution Approach 1:
The patent applies parameter changes by modifying the solvent system parameters and polymer-solvent interaction characteristics. It selects specific solvents and solvent ratios that provide adequate homogenization and stability without excessive cloud point depression, and adjusts the polymer formulation (monomer composition, concentration) to compensate for solvent effects and maintain the desired cloud point.
4Adaptability or versatility
If salts are added to the hydrogel formulation, then certain material properties are altered, but the cloud point is decreased due to salting-out effect
Solution Approach 1:
The patent uses parameter changes by adjusting the ionic strength and salt concentration parameters in the formulation. It selects specific salts and concentrations that provide necessary functional properties while minimizing cloud point depression, and modifies the polymer structure (through monomer selection and composition) to reduce sensitivity to ionic strength variations.
Solution Approach 2:
The patent converts the harmful salting-out effect into a beneficial feature by utilizing salt-induced cloud point shifts to achieve precise control over gelation timing and material properties. The salt effect, while generally problematic, is harnessed to create formulations that can be tuned for specific application requirements.
5Adaptability or versatility
If pH-sensitive monomers with hydroxyl or carboxylic acid groups are used, then pH responsiveness is achieved, but acidic or basic excipients alter the material properties and gelation conditions
Solution Approach 1:
The patent applies parameter changes by adjusting the pH and ionic strength parameters to control the behavior of ionizable monomers. It selects appropriate pH ranges and buffer conditions that maintain stable material properties while enabling pH-responsive functionality, and modifies the monomer composition to reduce sensitivity to pH variations from excipients.
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 APS enables a wide range of material properties and behaviors, allowing for tailored phase changes and multi-ingredient formulations in applications like medical sealing, drug release, cosmetics, skincare, industrial materials, and smart apparel, without compromising on stimulus response or material properties.
Implementation Method 1
this change in behavior is commonly observed as a transition from a clear liquid to an opaque gel above a certain trigger temperature, commonly referred to as a cloud point (Tcp)
Implementation Method 2
This behavior, often a change in the physical state of the material, is facilitated by a sensitivity to pH, temperature, light, or another stimulus
Implementation Method 3
the inclusion of additional solvents like alcohols (isopropyl alcohol, ethanol, methanol, etc.) has demonstrated something known as the co-solvent effect—a lowering of the Tcp
Implementation Method 4
Another effect that has also been well documented is the impact of salts on the hydrogel transition. Hoffmeister series ions all decrease the Tcp to varying degrees. This 'salting-out' effect
Implementation Method 5
Another effect that has also been documented is the pH sensitivity of smart hydrogel transitions from liquid to solid. Certain monomers, specifically those with hydroxyl or carboxylic acid groups have also demonstrated an LCST that can be manipulated based on the pH of the overall smart hydrogel
Data Source
AI summary
Described herein are compositions and uses for an adaptive polymer system. Components of the polymer are used to balance smart behavior around an environmental trigger point with desirable material properties and formulation additives. The APS allows engineering of smart materials and products with desired smart behaviors and material properties on both sides of the trigger point for that behavior. When applied to solvent-based polymer gels, the APS allows for precise control of cloud point behavior and material properties that enable a range of consumer, biomedical, and industrial applications.