This review covers the preparation, characterization, properties, and applications of methylcelluloses (MC). In particular, the influence of different chemical modifications of cellulose (under both heterogeneous and homogeneous conditions) is discussed in relation to the physical properties (solubility, gelation) of the methylcelluloses. The molecular weight (MW) obtained from the viscosity is presented together with the nuclear magnetic resonance (NMR) analysis required for the determination of the degree of methylation. The influence of the molecular weight on the main physical properties of methylcellulose in aqueous solution is analyzed. The interfacial properties are examined together with thermogelation. The surface tension and adsorption at interfaces are described: surface tension in aqueous solution is independent of molecular weight but the adsorption at the solid interface depends on the MW, the higher the MW the thicker the polymeric layer adsorbed. The two-step mechanism of gelation is confirmed and it is shown that the elastic moduli of high temperature gels are not dependent on the molecular weight but only on polymer concentration. Finally, the main applications of MC are listed showing the broad OPEN ACCESSPolymers 2015, 7 778 range of applications of these water soluble cellulose derivatives.

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The effects of polysaccharides, including xyloglucan from Hymenaea courbaril (XG), galactomannans from Schizolobium parahybae (GMSP) and Mimosa scabrella (GMMS), xanthan gum (XT), sodium hyaluronate (HNa) and Fucogel(®) (FG), on the rheological behavior of cosmetic emulsions were evaluated. These incorporations gave rise to six emulsified systems, denoted XGE, GMSPE, GMMSE, XTE, HNaE and FGE, respectively. The emulsion consistency was found to follow the trend GMSPE>XGE>HNaE>FGE>XTE>GMMSE. In general, the addition of polysaccharides increased the viscoelastic properties of the emulsions and decreased the creep compliance. The neutral polysaccharides (GMSPE, GMMSE) led to better stability of the emulsions after storing for 20 days relative to charged polymers. It was found that polysaccharides XG, GMSP and GMMS, which come from the seeds of native Brazilian plant species, might be used to modify the flow properties and stabilities of oil-water emulsions.

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An exocellular β-(1→6)-D-glucan (lasiodiplodan) produced by a strain of Lasiodiplodia theobromae (MMLR) grown on sucrose was derivatized by sulfonation to promote anticoagulant activity. The structural features of the sulfonated β-(1→6)-D-glucan were investigated by UV-vis, FT-IR and (13)C NMR spectroscopy, and the anticoagulant activity was investigated by the classical coagulation assays APTT, PT and TT using heparin as standard. The content of sulfur and degree of substitution of the sulfonated glucan was 11.73% and 0.95, respectively. UV spectroscopy showed a band at 261 nm due to the unsaturated bond formed in the sulfonation reaction. Results of FT-IR and (13)C NMR indicated that sulfonyl groups were inserted on the polysaccharide. The sulfonated β-(1→6)-D-glucan presented anticoagulant activity as demonstrated by the increase in dose dependence of APTT and TT, and these actions most likely occurred because of the inserted sulfonate groups on the polysaccharide. The lasiodiplodan did not inhibit the coagulation tests.

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