{'fraction_non_alphanumeric': 0.020318021201413426, 'fraction_numerical': 0.0035335689045936395, 'mean_word_length': 5.511494252873563, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Preparation and characterization of hydroxybutyl chitosan

Abstract The insolubility in neutral condition is a major problem that confronts the further development of processing and uses of chitosan. Special emphasis has been put on the chemical modification of chitosan to explore its full potential. Studies on these methods are also encouraging and many kinds of water-soluble and alcohol-soluble derivatives have been prepared. In this article, hydroxybutyl chitosan, a new type of thermosensitive polymer, was prepared through the chemical modification of 1,2-epoxybutane. According to the FT-IR spectra, hydroxybutyl chitosan has the same basic structure as chitosan, and hydroxylbutyl group has been linked in the main chain. XRD shows that the solubility of hydroxybutyl chitosan has been improved. Hydroxybutyl chitosan solution underwent sol/gel phase transition at a certain temperature lower than 20 °C, however, at high temperature, hydroxybutyl chitosan can form hydrogel with a certain mechanical strength. Hydroxybutyl chitosan could be an ideal thermosensitive material which can be applied in drug delivery system.