Crosslinked Polypyrrole Films for Nitrate-Selective Electrodes

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Solution Overview

Problem

Current nitrate sensors lack sensitivity and selectivity, and conventional methods for detecting nitrogen in water or soil samples are slow and costly, limiting the understanding of nitrate release and transport in environmental systems.

Innovation Solution

Development of nitrate-selective electrodes using crosslinked polypyrrole films with alkyl dihalide crosslinkers, which alter the electrochemical properties to enhance ion mobility and binding capacity, allowing for high sensitivity and selectivity in nitrate detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional nitrate sensors are used, then nitrate detection can be performed, but sensitivity and selectivity are insufficient

Engineering Contradiction:

Improvenitrate detection sensitivity and selectivityVSAvoiddetection accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies parameter changes by systematically varying the alkyl chain length (C1-C6) of dihalide crosslinkers to optimize the pore structure and electrochemical properties of polypyrrole films. This allows tuning of ion transport characteristics to enhance nitrate detection sensitivity and selectivity while maintaining measurement reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite materials by crosslinking polypyrrole chains with alkyl dihalides to form a structured network with controlled porosity. This composite structure combines the electrochemical activity of polypyrrole with the structural organization provided by crosslinking, improving both sensitivity and reliability of nitrate detection

Inventive Principle:

Principle #40Composite materials

2Productivity

If conventional detection methods are used, then nitrogen levels can be measured, but the process is slow and costly

Engineering Contradiction:

Improvedetection speedVSAvoidanalysis time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent replaces slow conventional chemical analysis methods with electrochemical detection using modified polypyrrole sensors. This substitution enables real-time or near-real-time monitoring of nitrate levels, dramatically increasing productivity while minimizing time loss

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If polypyrrole films are crosslinked with alkyl dihalides, then ion mobility and binding capacity are enhanced, but film structure complexity increases

Engineering Contradiction:

Improveion binding capacityVSAvoidfilm structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses parameter changes by varying the alkyl chain length of crosslinkers to control the degree of crosslinking and resulting film structure. This allows optimization of ion binding capacity while managing structural complexity through systematic parameter adjustment

Inventive Principle:

Principle #35Parameter changes

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 crosslinked polypyrrole films demonstrate improved sensitivity and selectivity for nitrate detection, enabling real-time monitoring of nitrate levels with higher spatial and temporal resolution, addressing the limitations of existing sensors and methods.

Implementation Method 1

Heteroatoms in these polymers undergo reversible electrochemical redox reactions to switch between lone-pair and cation-radical configurations, yielding high electrochemical capacity. These redox reactions also produce charge carriers (electrons and holes) that travel down the conjugated backbone of these polymers to produce high electronic conductivities

Methodology Applied

Scientific EffectElectrochemical redox reactions: Redox Reactions

Implementation Method 2

During electrochemical charge/discharge cycling, this reversible cation-radical/lone-pair process leads to reversible binding and releasing of anions from the electrolyte, making these materials of interest as anion-insertion electrodes for aqueous desalination and as anion-insertion cathodes for aqueous dual-ion batteries

Methodology Applied

Scientific EffectAnion insertion: Adsorption

Data Source

PatentUS20230365819A1Effects of interchain crosslinking by alkyl dihalides on the electrochemical performance of nano-scale polypyrrole films

Publication Date: 2023.11.16 THE CURATORS OF THE UNIVERSITY OF MISSOURI

AI summary

Disclosed are the electrochemical effects of crosslinking polymer chains in nanoscale polypyrrole films with aliphatic ethyl (Ppy-Et), propyl (Ppy-Pr), and butyl (Ppy-Bu) groups were investigated. The films are synthesized by pulsed-electrodeposition of polypyrrole followed by a crosslinking reaction with an alkyl dihalide (dibromoethane, dibromobutane, or dibromopropane) in methanol. By changing the length of the alkyl-dihalide crosslinker, it was shown that one can adjust the properties of the polypyrrole films to achieve properties not typical for polypyrrole. The resulting materials exhibit valuable properties in two areas: (1) excluding anions from transport through the polymer, allowing for the creation of cation-selective membranes using polpyrrole crosslinked with ethyl (2 carbon) crosslinker molecules and (2) enhancing the specific capacity by >50% relative to the uncrosslinked polymer using propyl (3 carbon) crosslinker molecules. These materials have potential value for energy storage, electrochemical desalination, membrane separations, and chemical sensors.