I assume paper is mostly cellulose, containing lots of hydroxyl groups.
Can it be chemically modified for interaction with specific molecules?
There are many ways how to chemically modify the paper. I present a few examples:
- cellulose in paper can be acylated via esterification with acylhalogenide or anhydride in an unhydrous environment
- another method is "nitration" of cellulose with 100% HNO3 /in liquid or gaseous phase/ or with various nitration mixtures /HNO3 in acetanhydride, HNO3 + HCCl3, HNO3 in H2SO4 ...etc./
- via alkylation with e.g. DMS /CH3/2SO4 in water solution of NaOH at elevated temperatures, instead of DMS also alkylhalogenide /mostly CH3I/ can be used
- via reaction with alkeneoxdides at alkaline pH. This reaction yields hydroxyalkyl derivatives of cellulose /the reaction site is mostly C6 primary alcoholic group/
- alkylation of cellulose can be performed also directly with anhydrous alcohol in which the gaseous HCL as a catalyst is dissolved
- it can be carboxymethylated with Cl-CH2-COOH in alkaline solution,
- cellulose in paper can be xantogenated with CS2 in a solution of NaOH in water dispersion /cellulose xantogenate, however, dissolves in the reaction mixture/
- oxidation of primary alcoholic group of 1,4 beta- anhydroglucopyranose units with N2O4 leads to carboxycellulose with various degree of -COOH groups depending on the reaction conditions
- a number of grafting and crosslinking reactions of cellulose /reactions with metacrylic acid, maleinic acid etc./
Note: supramolecular structure of cellulose comprising both highly ordered macromolecules /cristalline portion/ and amorphous portion, determines reaction kinetics of this biopolymer. In general , the rate of reactions of amorphous cellulose is higher, and reasoctions are completed sooner. From this reason is the cellulose often treated with NaOH water solutions to relax the cristalline portions of this biopolymer prior to its chemical processing .
R.S.
Cellulose can indeed be functionalized easily because of the many -OH groups, very easy to react for doing other moieties. But paper is cellulose plus many other things. Writing paper is full of inorganic fillers, but still can be functionalized. Kimwipe paper is even more special, as it contains polysiloxane, as far as I know. Its functionalization should be possible, but I expect that this kind of paper is far less reactive than cellulose alone.
Alain
Anil,
look please to Q/A, I have the same question answered to your coworker.
R.S.
I think, we should consider 3 important points in paper modification:
1- The aim of modification
2- Selection the best method
3- Selection the best chemicals
Also it should be noted that the paper fibers depending to their kind (chemical pulps or mechanical pulps/bleached or unbleached) have different reaction point (for example, the presence of Lignin introduces more different reaction points but in the bleached pulps, the cellulose has more important role) . Also the PROPORTION of reaction points even in cellulosic parts differs in different pulp.
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