TEMPO-oxidized wood celluloses (TOCs) with carboxylate contents &gt; 1 mmol/g can be converted to completely individualized TOC nanofibrils (TOCNs) with uniform widths of ~3 nm by mechanical disintegration of TOCs in water. TOCNs have potential applications as TOCN-containing composite materials, TOCN hydrogels, aerogels, films, and others having unique properties and functions. In these cases, not only length/length distribution but also molecular mass/molecular mass distribution of TOCs and TOCNs are supposed to have strong influence on the mechanical and other functional properties of the resulting bulk TOCN materials and TOCN-containing composites. So far, freeze-dried TOCs and TOCNs have been dissolved in 0.5M copper ethylenediamine, and viscosity average degrees of polymerization (DPv) have been used to evaluate their molecular mass values based on some assumptions. In this paper, a position-selective methylation of carboxyl groups was carried out to TOCs and TOCNs with trimethylsilyldiazomethane under mild conditions, and the carboxyl groups-methylated TOCs and TOCNs are dissolved in 8% LiCl/DMAc followed by subjecting to SEC-MALLS analysis after diluting to 1% LiCl/DMAc to determine their molecular masses and molecular mass distributions. The results showed that molecular masses of TOCs decreased with increasing NaClO addition level in the TEMPO-mediated oxidation, and those of TOCNs further decreased with increasing sonication time in disintegration treatment in water. Moreover, the viscosity method underestimated the molecular mass values of TOCs and TOCNs. A part of hemicelluloses originally present in wood cellulose partly remained in TOCs, depending on the oxidation conditions. Based on the obtained results, the distribution patterns of disordered regions susceptible to TEMPO-oxidation present periodically along the longitudinal direction of each cellulose microfibril are discussed.

Determination of molecular mass and molecular mass distribution of TEMPO-oxidized celluloses (TOCs) and TOC nanofibrils (TOCNs) using SEC-MALLS

249th National Meeting (2015)

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