Characterization Grafted Polysaccharides

The hydroxo-initiator R OH may be a polysaccharide or may be modified by a certain degree of substitution by hydroxyl groups (Scheme lb). Following this scheme, many graft copolymers have been synthesized and characterized ... 

Modification of natural polysaccharides through various graft copolymerization techniques is discussed in this chapter. Characterization of graft copolymers using different techniques like FT-IR, C-NMR, SEM, XRD, TGA, DTA and DTG along with their physical, chemical and mechanical properties are discussed as a function of different reaction conditions of their synthesis. Applications for modified polysaccharides include drug delivery devices, controlled release of fungicides, selective water absorption from oil-water emulsions and purification of water. 

In the particular case of polysaccharides, this reaction has been used for the modification of several types of biopolymers with different applications [28, 29]. As an example, a monoaldehyde derivative of P CD (2) was prepared from the hydrolysis of product 1 and then grafted, by a reductive amination-type reaction, onto an alginate derivative selectively modified with adipic dihydrazide (alg-ADH) (Scheme 7.5). The new polymeric materials obtained, alg-ADH intermediate and jS-CD-grafted alginate were fully characterized in terms of chemical integrity and purity by high-resolution NMR spectroscopy [30]. 

Thakur VK, Singha AS, Thakur MK (2012d) Modification of natural biomass by graft copolymerization. Int J Polym Anal Charact 17 547-555 Thakur VK, Thakur MK (2014a) Processing and characterization of natural cellulose fibers/ thermoset polymer composites. Carbohydr Polym 109 102-117 Thakur VK, Thakur MK (2014b) Recent trends in hydrogels based on psyllium polysaccharide a review. J Cleaner Product 82 1-15... 

Graft polymerization of L-lactide on mostly trimethylsilylated polysaccharides were carried out according to Scheme 2. Following procedures show the typical example using TMSAm-1. The procedures were basically carried out in a dry glove box under Ar atmosphere. TMSAm-1 (36.6 mg) was dissolved in dry THF. t-BuOK (2.2 mg, 0.02 mmol) dissolved in dry THF (0.5 mL) was added to the solution. After stirring for 1 hour, L-lactide (228.3 mg, 2.0 mmol) in THF (0.75 mL) was added. The polymerization was terminated when the reaction proceeded for 5, 10, 30 or 90 min, by the addition of excess amount of acetic acid in THF to the reaction mixture. The obtained products were precipitated with ethyl ether. Characterization of the TMS protected graft copolymer was performed by H-NMR. 

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