Abstract
Crosslinking is one of the most commonly reactions used to improve the physical properties of cellulose derivatives. Cellulose Acetate Propionate (CAP) is a commercial ester obtained as a cellulose derivative and it can be used as basis for the synthesis of crosslinked chains as described in this work. Typical used crosslinkers are di-functional compounds, such as dianhydrides or diisocyanate. The formation of polymeric 3D structures as described in this work occurs typically by the reaction of the linear chains bearing free OH groups with crosslinking agents such as dianhydrides. These reactions are used to make a very absorbent material, typically a gel. The syntheses were performed in homogeneous medium with acetate propionate in a very dry atmosphere by employing PMDA (Pyromellitic Dianhydride) and BTDA (3,3’, 4,4’ Benzophenone Tetracarboxylated Dianhydride) as crosslinking agents in a reflux system. TGA analysis has shown the different thermal stability of the gels when compared with CAP. Typical TGA curves have demonstrated the lower stability of the crosslinked chains when compared to CAP as consequence of esther linkages formed in the gels structures. The Mc, which is the value for the molar mass between crosslinkings points in 3D structure, was determined according to Flory-Rehner theory. This important parameter has demonstrated greater reactivity of PMDA in comparison with the BTDA in the reactions conditions’ employed in this work.
Highlights
Chemical modifications of conventional organic polymers are important techniques to explore new materials having prospects of improved properties [1,2]
Cellulose Acetate Propionate (CAP) is a commercial ester obtained as a cellulose derivative and it can be used as basis for the synthesis of crosslinked chains as described in this work
The Density of crosslinking and average molar mass between crosslink points show that the gel prepared with Pyromellitic Dianhydride (PMDA) has a greater number of crosslinkings suggesting greater reactivity with this agent
Summary
Chemical modifications of conventional organic polymers are important techniques to explore new materials having prospects of improved properties [1,2]. Many polymers have been employed in the production of gels and generally three classes are important: 1) natural [6]; 2) polyacrylamide [9] and 3) polyacrylate polymers [9,10,11] The applicability of these materials depends mainly on its ability to absorb water or fluids. The products are formed at room temperature its development based on the reaction of the linear chains of CAP bearing free OH groups with crosslinking agents as dianhydride. These reactions form of a very absorbent material, typically a gel. There are great possibilities for use of gels in drug controlled release systems that are being investigated
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