Lignin-containing polymers preparation

Liquefied wood is also an interesting raw material for polymer preparation. Wood flour contains lignin, cellulose, and hemicellulose, and can be liquefied with phenol or glycol in the presence of an acid or base catalyst, or at high temperature (>250 °C) or in sub-/super-critical fluid e.g. water, alcohols, and... 

Of course, the picture given in the preceding paragraph cannot apply to the almost pure lignin in the true middle lamella. Here the lamellar thickness is usually more than 100 nm (83,84). The concept of a random three-dimensional network polymer would seem to be appropriate for such a thick layer. However, the true middle lamella probably contains less than 20% of the total lignin (83,84,102). Thus, lignin from the secondary wall will be the dominant fraction in most preparations from whole wood. 

Figure 9.14 AFM images (tapping mode) of a five-bilayer film of HCI-doped POEA layers alternated with SL layers, showing the surface of the fifth layer of POEA (500 nm x 500 nm 3-D image) (a) I mu x 1 mu image of a film containing only one layer of POEA and its cross-section profile (b) 1 mu x 1 mu image of a film containing one bi layer ofPOEA/SL and its cross-section profile. (Reprinted with permission from Polymer, Effect of pH on the preparation of self-assembled films of polyfo-ethoxyaniline) and sulfonated lignin by Leonardo G. Paterno and Luiz H. C. Mattoso, 42, 12, 5239-5245. Copyright (2001) Elsvier Ltd)...

S. K. Samal, E.G. Fernandes, A. Crati, E. Chiellini. Bio-based Polyethylene-Lignin Composites Containing a Pro-oxidant/Pro-degiadant Additive Preparation and Characterization , J. Polym. Environ., 22, 58-68 (2014)... 

A fraction analogous to BjOrkman lignin (39) was obtained when a portion of finely-powdered suberin polymer from the periderm of 5. tuberosum was solubilized with dioxane. This soluble fraction, however, was not enriched in either aromatic or aliphatic components over the insoluble residue (unpublished results). Other procedures from lignin chemistry - including refluxing in HCl/dioxane or HCl/dimethylformamide, and dioxane treatment at 160 C and high pressure (268, 396) - resulted in 20 o to 50% solubilization of the suberin preparation, but with each method the insoluble material contained the majority... 

Initial studies, primarily done on suberin from the periderm of S. tuberosum give additional indication of the secondary structure of the polymer. Enriched preparations of suberin always contain high levels of carbohydrate (as much as 50 o). Obviously the suberin-enriched preparations contain covalently attached cell wall carbohydrates and the linkages between suberin and carbohydrate may be similar to those proposed for the attachment of lignin to carbohydrate (132, 268). Chemical studies on the polymer have shown that very few of the hydroxyl groups of cu-hydroxy acids are free and that the polymer has very few (< 5%) free aliphatic carboxyl moieties (230). Fractionation of S. tuberosum suberin by partial solubilization with 1 % HCl/dioxane has indicated that the aliphatic components may be in separate domains, for polymeric fractions that contained a larger proportion of fatty acids and fatty alcohols but a lower proportion of cu-hydroxy acids and dicarboxylic acids have been isolated. These fatty acids and fatty alco-... 

Lignin sulfonates are, technically, low-molecular-weight polymers containing a witch s brew of primary and secondary alcohols, phenols, and carboxylic acid functionalities. They are prepared by the sulfonation of lignin byproducts of pulp and paper manufacture, followed by neutralization to the sodium, calcium, or ammonium salt. The resulting materials are useful as dispersing agents for solids and oil/water emulsions, and as stabilizers for aqueous dispersions of dyes, pesticides, and cement. They are very inexpensive relative to other materials and are very... 

---