# Emergence of Coherent Nanoscale Structures in Carbon Nantotubes

## TL;DR

This paper models how water confined in carbon nanotubes can form coherent nanoscale structures, explaining the unusually high freezing points and their dependence on nanotube diameter, aligning with recent experimental observations.

## Contribution

It introduces a theoretical model predicting coherent nanoscale water structures in CNTs and explains the diameter-dependent phase transition temperatures.

## Key findings

- Water in CNTs can form coherent nanoscale structures.
- Phase transition temperature scales inversely with the square of the effective radius.
- Model predictions align qualitatively with empirical data.

## Abstract

Recently unusual properties of water in single-walled carbon nanotubes (CNT) with diameters ranging from 1.05 nm to 1.52 nm were observed. It was found that water in the CNT remains in an ice-like phase even when the temperature ranges between 105 - 151 C and 87 - 117 C for CNTs with diameters 1.05 nm and 1.06 nm respectively. Apart from the high freezing points, the solid-liquid phase transition temperature was found to be strongly sensitive to the CNT diameter. In this paper we show that water in such CNT's can admit coherent nanoscale structures provided certain conditions are met. The formation of such coherent structures allows for high values of solid-liquid phase transition temperatures that are in qualitative agreement with the empirical data. The model also predicts that the phase transition temperature scales inversely with the square of the effective radius available for the water flow within the CNT. This is consistent with the observed sensitive dependence of the solid-liquid phase transition temperature on the CNT diameter.