CNT-Polymer Complex Self-Doping via Stimuli-Responsive Block Copolymers
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Solution Overview
Problem
Existing methods for dispersing carbon nanotubes (CNTs) using conjugated polymers, such as PEDOT/PSS, face issues with long-term shelf stability and substrate damage due to ionic groups, and pH and water dispersion can be problematic for organic electronics, affecting device performance.
Innovation Solution
A CNT-polymer complex is developed using a block copolymer of a conjugated polymer and a non-conjugated polymer, where the non-conjugated polymer includes protected functional groups that provide dopants by external stimuli, allowing self-doping and improved conductivity, and the complex is soluble in organic solvents in a neutral state but insoluble after external stimuli, enabling a solution process without aqueous phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional doping methods using ionic polymers (e.g., PEDOT/PSS) are used, then electrical conductivity is improved, but long-term shelf stability deteriorates due to ionic groups
Solution Approach 1:
The patent changes the chemical nature of dopant groups from ionic (sulfonate, carboxylate) to neutral (sulfone, carboxyl, acryl, phosphate groups). This parameter change in the functional group type eliminates the harmful ionic character while retaining doping capability, thereby improving both conductivity and long-term stability without the degradation issues associated with ionic groups
Solution Approach 2:
The patent uses a block copolymer composite structure combining conjugated polymer (for conductivity) and non-conjugated polymer (for solubility and dopant delivery). This composite approach allows the material to achieve both high electrical conductivity through the conjugated segment and enhanced stability through the neutral dopant groups on the non-conjugated segment, resolving the contradiction between conductivity and shelf stability
2Ease of operation
If aqueous solution processing is used for dispersion, then solubility is improved, but substrate damage occurs due to pH and water sensitivity
Solution Approach 1:
The patent changes the solubility parameter from water-based to organic solvent-based by designing the polymer with neutral functional groups and hydrophobic character. This allows the material to be processed in organic solvents rather than aqueous solutions, eliminating pH-related and water-induced substrate damage while maintaining ease of solution processing
Solution Approach 2:
The non-conjugated polymer block acts as an intermediary that provides solubility in organic solvents without requiring water or pH adjustment. This intermediary structure enables solution processing while avoiding the harmful effects of aqueous environments on substrates
3Stability of the object's composition
If covalent bonding dispersion methods are used, then dispersion uniformity is improved, but electrical properties deteriorate due to surface defects
Solution Approach 1:
The patent segments the dispersion approach into two independent parts: the conjugated polymer block provides uniform dispersion through non-covalent interactions, while the non-conjugated polymer block with neutral dopant groups provides stable coating. This segmentation allows each component to perform its specific function without the negative effects of covalent bonding, maintaining both dispersion uniformity and electrical properties
4Object-affected harmful factors
If neutral polymers are used for dispersion, then substrate compatibility is improved, but conductivity is reduced due to lack of doping
Solution Approach 1:
The patent creates a composite block copolymer where the conjugated polymer segment provides electrical conductivity through electron delocalization, while the non-conjugated polymer segment with neutral dopant groups provides substrate compatibility and solubility. This composite structure allows both neutral substrate compatibility and adequate conductivity to coexist, resolving the contradiction between these two properties
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 CNT-polymer complex achieves enhanced electrical conductivity and improved solvent selectivity, with the film formed by external stimuli being insoluble to both aqueous and organic solvents, thus increasing the range of solvent selection and stability in subsequent processes.
Implementation Method 1
a block copolymer of a conjugated polymer bound firmly to the surface of carbon nanotubes (CNT) via pi-stacking
Implementation Method 2
capable of self-doping by external stimuli, as well as to a process for preparing the same
Implementation Method 3
provides at least one dopant selected from the group consisting of a sulfone group, carboxyl group, acryl group and phosphate group by external stimuli so that self-doping is allowed
Data Source
AI summary
Provided are a CNT-polymer complex and a process for preparing the same. The CNT-polymer complex includes carbon nanotubes (CNT) coated with a block copolymer of a conjugated polymer and a non-conjugated polymer, wherein the non-conjugated polymer comprises at least one monomer selected from the group consisting of styrene, butadiene, isoprene, methacryl, acryl, acryl amide, methacryl amide, acrylonitrile, vinyl acetate, vinyl pyridine and vinyl pyrrolidone in which at least one selected from the group consisting of a sulfone group, carboxyl group, acryl group and phosphate group is protected with a protective group, and provides at least one dopant selected from the group consisting of a sulfone group, carboxyl group, acryl group and phosphate group by external stimuli so that self-doping is allowed; and the complex is soluble to an organic solvent in a neutral state but is insoluble to any solvent after subjecting it to external stimuli.