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In the present work, The results of 13CNMR, 23Na NMR and 15N NMR confirmed that formation of the expanded inclusion complex (IC) of urea hydrate surrounding the NaOH hydrogen-bonded chitin led to the dissolution of the most intransigent chitin.A combination of static and dynamic light scattering (SLS and DLS) was utilized to investigate the weight-average molecular weight (Mw) and parameters of chitin dilute solution dissolved in NaOH/urea aqueous system via the freezing/thawing method.The results revealed that isolated chains (individuals) as stiff chain and their aggregates as micro-and nano-gel particles coexisted in the chitin dilute solution, and the weight-average molecular weight of the chitin (Mw,mdi for individuals) was determined satisfactorily.The structure-sensitive dimensionless parameters ρ of the isolated chitin chains of 2.04 indicated an extended stiff chain conformation in the dilute solution.Moreover, the fractal dimension (df) of the chitin micro-or nano-gel particles was in the range from 2.23 to 2.48, suggesting a 3D network structure.The AFM and TEM images provided direct evidence of rod-like chain for the individuals and the network structure for the chitin gels.