Helical Multi Walled Carbon Nanotubes

Quick Summary: Helical Multi-Walled Carbon Nanotubes

  • What they are — Coiled MWCNTs with spring-like helical geometry, ~80 wt% helical content
  • Outer diameter — 100–200 nm (most tubes in this range)
  • Carbon nanotube content — >90 wt% total CNTs (helical + straight)
  • Key advantage — Inductive electrical response, broader EMI shielding bandwidth, mechanical interlocking in composites
  • Best for — EMI shielding, microwave absorption, sensor windings, structural composites at low loading

Helical Multi-Walled Carbon Nanotubes

Helical multi-walled carbon nanotubes are coiled CNT structures grown to wrap around themselves in a continuous spring-like geometry — not the straight, parallel tubes most carbon nanotube applications use.

Cheap Tubes’ helical MWCNTs contain approximately 80 wt% helical morphology with the remainder in standard straight-tube form, total carbon nanotube content above 90 wt%, and outer diameters concentrated in the 100–200 nm range.

The helical geometry is engineered, not incidental: it changes how the material couples to electromagnetic fields, conducts current, and interlocks with surrounding matrices.

Shop this grade: Helical Multi-Walled Carbon Nanotubes — see the product page for current quantity-based pricing.

Why choose helical over straight MWCNTs

Straight MWCNTs are the default choice for most conductive, thermal, and structural applications — they’re cheaper, easier to disperse, and the property data is more extensively published. Helical MWCNTs are the better choice when the coiled geometry adds physical value:

  • EMI shielding and microwave absorption — the helical geometry provides broader frequency coupling than straight tubes, so a helical-CNT composite shields a wider EM bandwidth at lower loading.
  • Inductive electrical response — each coil behaves as a microscopic inductor, enabling sensor architectures that exploit inductive rather than purely resistive transduction.
  • Mechanical interlocking — the spring shape provides geometric anchoring with polymer or ceramic matrices, improving composite toughness at lower CNT loadings than straight tubes.
  • Volume-change resilience in electrodes — the coiled geometry accommodates electrode swelling during charge cycling without the conductive network fragmenting.

Characterization and documentation

Every lot ships with a Technical Data Sheet (TDS) including SEM imaging that confirms the helical morphology, Raman spectroscopy (D and G band ratio for crystallinity), TGA for purity and ash content, and BET surface area measurement. A Safety Data Sheet (SDS) is included in the order documentation. For research applications requiring additional characterization (XPS, EDS, particle size distribution), contact us before ordering and we can quote the additional analytical work.

Ordering and pricing

Pricing is per gram and decreases at higher quantities. To see current pricing for a specific quantity, click through to the product page and enter your target quantity — the cart displays per-quantity pricing in real time. For orders above 100 g or custom morphology requirements, contact us directly for a quote.

Frequently Asked Questions

What are helical multi-walled carbon nanotubes?
Helical MWCNTs are coiled carbon nanotubes grown to wrap around themselves in a continuous spring-like geometry. Cheap Tubes’ helical MWCNTs are approximately 80 wt% helical morphology with the balance straight CNTs, total carbon nanotube content above 90 wt%, with most tubes in the 100-200 nm outer diameter range.

How do helical CNTs differ from straight MWCNTs?
The coiled geometry produces an inductive electrical response (helical CNTs behave like microscopic inductor coils), enhanced electromagnetic interference shielding from broader frequency coupling, and improved mechanical interlocking in composite matrices. Straight MWCNTs are preferred for purely conductive or thermal applications; helical MWCNTs are preferred where the spring geometry adds value — EM shielding, microwave absorption, sensor windings, and mechanical reinforcement at low loadings.

What applications use helical carbon nanotubes?
Primary applications are electromagnetic interference (EMI) shielding composites, microwave absorbers and stealth coatings, electrochemical sensors that exploit the high surface area and inductive response, energy-storage electrodes (the spring geometry resists volume change during cycling), and structural composites where the coiled shape provides mechanical interlocking with the matrix at lower loadings than straight CNTs.

What characterization data ships with the product?
Each lot ships with a Technical Data Sheet (TDS) including SEM imaging showing the helical morphology, Raman spectroscopy (D and G band ratio), TGA for purity and ash content, and BET surface area. A Safety Data Sheet (SDS) is included in the order documentation.

Is bulk pricing available?
Yes. Quotes for orders above 100 g are issued individually based on quantity, lead time, and any custom characterization requirements. Add the product to your cart and request a quote, or contact us directly with your target quantity and application.

What Are Helical Carbon Nanotubes?

Helical multi-walled carbon nanotubes (HMWCNTs) — also called coiled, spring-shaped, or toroidal CNTs — are a structurally distinct form of multi-walled nanotube in which the tube axis follows a helical path rather than a straight line. This coiled geometry arises from the periodic introduction of five- and seven-membered carbon rings (pentagons and heptagons) into the otherwise hexagonal graphene lattice during synthesis. Each pentagon introduces a positive curvature and each heptagon introduces a negative curvature; alternating pairs produce the regular helical winding observed in HMWCNTs.

Cheap Tubes offers helical MWCNTs with outer diameters of 100–200 nm and a helical content exceeding 80 wt% of the product. The remaining fraction consists of standard straight MWCNTs that grow simultaneously during synthesis. Total CNT content exceeds 90 wt%.

Structural Characteristics

Property Value
Outer Diameter 100–200 nm
Coil Diameter 300–500 nm
Helical Pitch Variable (100–500 nm)
Helical Content >80 wt%
Total CNT Purity >90 wt%
Carbon Content >90%
Synthesis Method CVD with specific catalysts

The coiled geometry has been confirmed by selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM), which reveal the graphitic layered wall structure and the continuous winding of the tube axis. Variable helix angles and polygonal cross-sections are observed at high magnification, consistent with the stress induced by the topological defects that drive helical growth.

Unique Properties Arising from Helical Geometry

The spring-like geometry of helical CNTs gives them properties not found in straight nanotubes. Most significantly, HMWCNTs behave as nanoscale mechanical springs with exceptionally high resilience — they can be compressed and stretched repeatedly without plastic deformation, recovering their original geometry elastically. This is analogous to a macroscopic metal coil spring, but at nanoscale dimensions and with carbon’s characteristic low density and high chemical stability.

The helical winding also generates a continuous magnetic moment when carrying current, giving HMWCNTs intrinsic electromagnetic inductance not present in straight CNTs. This property is being explored for microwave absorption, nanoscale inductors, and electromagnetic metamaterials.

Applications of Helical Carbon Nanotubes

Electromagnetic Wave Absorption

The most commercially advanced application for HMWCNTs is microwave and radar absorption. The helical geometry creates a resonant electromagnetic structure that couples efficiently to electromagnetic waves, converting microwave energy to heat through ohmic losses. At 5–30 wt% loading in rubber or polymer matrices, HMWCNT composites achieve reflection loss exceeding 20 dB (99% microwave absorption) across broad frequency ranges (2–18 GHz). This performance surpasses standard CNT composites of equivalent loading and makes HMWCNTs attractive for stealth coatings, EMI suppression, and anechoic chamber linings.

Mechanical Damping and Vibration Absorption

The spring-like mechanical behavior of HMWCNTs contributes to viscoelastic damping in polymer composites. At loadings of 1–5 wt%, HMWCNT composites show loss factors (tan δ) 2–5× higher than straight MWCNT composites at equivalent loading — a direct consequence of the reversible deformation and energy dissipation of the helical structure. Applications include vibration-damping structural panels, acoustic insulation composites, and impact-absorbing padding.

Stretchable and Flexible Electronics

When embedded in elastic substrates (PDMS, polyurethane), helical CNTs maintain electrical conductivity under large strains (50–200%) by accommodating substrate deformation through spring extension, rather than through plastic deformation of the nanotube itself. This makes HMWCNT/elastomer composites promising for stretchable electrodes in wearable sensors, artificial muscles, and soft robotics — applications where straight CNT networks lose conductivity under repeated stretching.

Nanoscale Sensing

Individual helical CNTs have been demonstrated as nanoscale force sensors, where the spring constant of the helix can be determined from resonance frequency measurements in a TEM. Arrays of HMWCNTs potentially function as nanoscale pressure sensors, accelerometers, or mass detectors with sensitivities far exceeding conventional MEMS devices.

Composite Reinforcement

The helical morphology provides mechanical interlocking with polymer matrices that straight CNTs do not offer. This enhances interfacial adhesion without chemical functionalization, improving stress transfer efficiency. HMWCNT-reinforced epoxy composites show 30–50% higher impact strength than straight MWCNT composites at equivalent loading, due to the crack-bridging and energy-dissipating behavior of the coiled tubes at fracture surfaces.

Research Background

Helical CNTs were first reported in the early 1990s and have been studied extensively for their unusual electromagnetic and mechanical properties. Their synthesis remains more challenging than straight MWCNTs — requiring specific catalyst formulations and CVD conditions to favor helical growth — which limits their availability and keeps pricing higher than standard MWCNTs. Cheap Tubes is one of the few commercial suppliers offering HMWCNTs in gram quantities for research and early-stage development.

Pricing is $12–15/g depending on quantity. Contact us for bulk pricing and to discuss application-specific requirements. SDS documentation is available from our SDS page.