Degradable Conjugated Polymers for SWCNT Sorting and Removal

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Solution Overview

Problem

The challenge in using single-walled carbon nanotubes (SWCNTs) in electronic devices is the removal of polymer chains attached to their sidewalls after sorting, which creates high inter-tube energetic barriers and inferior network connections, hindering their performance in semiconducting applications.

Innovation Solution

Conjugated polymers composed of bi-pyridine units linked to 9,9-dialkyl fluorenyl-2,7-diyl units via imine linkages are used to selectively coat and separate semiconducting SWCNTs from metallic SWCNTs, allowing for their purification and subsequent removal through acid or thermal depolymerization without damaging the SWCNTs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional polymer wrapping is used to sort semiconducting SWCNTs, then sorting selectivity is improved, but polymer removal becomes difficult and network connections deteriorate

Engineering Contradiction:

Improvesorting selectivityVSAvoidpolymer removal

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The polymer is segmented into degradable units that can be broken down into smaller components. The conjugated polymer backbone is designed with cleavable bonds that allow segmentation upon exposure to specific conditions (acid, base, or heat), enabling easy removal after sorting is complete.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polymer coating is extracted from the SWCNT surface through controlled degradation. After the polymer has served its sorting function, it is selectively removed using acid treatment, base treatment, or thermal degradation, leaving the SWCNTs free of coating for optimal network connections.

Inventive Principle:

Principle #2Taking out (Extraction)

2Stability of the object's composition

If polymer chains remain attached to SWCNT sidewalls after sorting, then sorting stability is maintained, but inter-tube energetic barriers increase and network connections become inferior

Engineering Contradiction:

Improvesorting stabilityVSAvoidnetwork connection quality

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The polymer is designed to perform its stabilizing function during sorting first, then undergo preliminary degradation treatment to remove itself. The controlled degradation (acid, base, or heat treatment) is applied after sorting to eliminate the polymer while preserving the sorted SWCNT composition.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The polymer's stability parameters are changed after sorting by exposing it to acidic conditions, basic conditions, or elevated temperatures. These parameter changes trigger degradation of the polymer backbone, transforming it from a stable coating during sorting to an removable substance afterward.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If degradable linkages are introduced into the polymer backbone, then polymer removal is facilitated, but polymer stability during sorting may be compromised

Engineering Contradiction:

Improvepolymer removalVSAvoidpolymer stability during sorting

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The degradable linkages are designed to resist degradation under sorting conditions but activate under removal conditions. The polymer backbone incorporates bonds that are stable during the sorting process but cleave selectively when exposed to acid, base, or heat treatment, preventing premature degradation while enabling easy removal.

Inventive Principle:

Principle #9Preliminary anti-action

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

This method achieves ultrahigh purity semiconducting SWCNTs with a high ratio of s-SWCNTs to metallic SWCNTs, suitable for use in field-effect transistors and photovoltaic cells, by effectively removing the polymer coating without affecting the electric and optoelectric properties.

Implementation Method 1

conjugated polyfluorene polymers are useful materials that have pi-pi interactions with a high degree of s-SWCNT selectivity

Methodology Applied

Scientific EffectPi-pi interactions:

Implementation Method 2

The conjugated polymer coating can then be removed from the separated single-walled carbon nanotubes by depolymerizing the conjugated polymer with acid

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Implementation Method 3

heating the conjugated polymer-coated semiconducting single-walled carbon nanotubes to a temperature at which the conjugated polymer thermally decomposes

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Data Source

PatentUS20180099870A1Degradable conjugated polymers for the selective sorting of semiconducting carbon nanotubes

Publication Date: 2018.04.12 WISCONSIN ALUMNI RES FOUND

AI summary

Conjugated polymers composed of bi-pyridine units linked to 9,9-dialkyl fluorenyl-2,7-diyl units via imine linkages along the polymer backbone are provided. Also provided are semiconducting single-walled carbon nanotubes coated with the conjugated polymers and methods of sorting and separating s-SWCNTs from a sample comprising a mixture of s-SWCNTs and metallic single-walled carbon nanotubes using the conjugated polymers.