(226bg) Effect of the Reaction Conditions on the Morphology of Polyglycerol Produced from the Polymerization Reaction of Glycerol Using Sulfuric Acid As Catalyst

The effect of the reaction conditions in the morphology of polyglycerol was studied. Polymerization of glycerol was performed using sulfuric acid as catalyst and the factors studied were temperature and catalyst percentage. Previous studies on the synthesis of polyglycerol from glycerol, has been focused in the development of catalysts to achieve high conversions and high molecular weights. Production of high molecular weight polyglycerol using sulfuric acid as catalyst has been accomplished, and it has been suggested that the use of this catalyst promote branched and cyclic polymer structures [1]. To the authors' knowledge, there have not been studies focused in the morphology of polyglycerol synthesized from glycerol. Polyglycerol is a glycerol valued-added product, a promising monomer in the production of biodegradable polymers. Polyglycerol is form by an ether backbone and abundant pendant hydroxyl groups. These pendant hydroxyl groups make polyglycerol a building block for diverse polymeric complexes [2]; for instance, polyglycerol is used as starting material for drug delivery [3,4] temperature-responsive co-polymers [5], and dyes adsorption from aqueous media [6], among many other applications [7-10]. The morphology and functionality of polyglycerol, such as degree of branching, molecular weight distribution, and hydroxyl number, plays an important role in the polymer application. The study of the effect of reaction conditions on the polyglycerol morphology was performed by a factorial design experiment. The response variables were hydroxyl number, molecular weight distribution, and degree of branching. Hydroxyl number was calculated according to ASTM D4274 standard. The weight distribution was found using a Mattrix-Assisted Laser Desorption/ Ionization-Time-Of-Flight (MALDI-TOF), and the degree of branching was found using Nuclear Magnetic Resonance (NMR). Additional Characterization was performed using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results suggest that it is possible to tune polyglycerol morphology changing reaction conditions. Temperature of reaction affects the degree of branching and the hydroxyl number of polyglycerol; whereas the molecular weight distribution is not affected. Variations of the glass transition temperature in the studied polyglycerol suggest changes in polyglycerol structures.

References

1. Salehpour, S. and M.A. Dubé, Towards the Sustainable Production of Higher-Molecular-Weight Polyglycerol. Macromolecular Chemistry and Physics, 2011. 212(12): p. 1284-1293.

2. Wilms D., S.-E.S., Hyperbranched Polyglycerols: From the Controlled Synthesis of Biocompatible Polyether Polyols to Multipurpose Applications. Accounts of chemical research, 2010. 43(1): p. 129-141.

3. Steinhilber, D., et al., Surfactant free preparation of biodegradable dendritic polyglycerol nanogels by inverse nanoprecipitation for encapsulation and release of pharmaceutical biomacromolecules. J Control Release, 2012.

4. Calderon, M., et al., Development of efficient acid cleavable multifunctional prodrugs derived from dendritic polyglycerol with a poly(ethylene glycol) shell. J Control Release, 2011. 151(3): p. 295-301.

5. Taylor, D.K., et al., Temperature-Responsive Biocompatible Copolymers Incorporating Hyperbranched Polyglycerols for Adjustable Functionality. J Funct Biomater, 2011. 2(3): p. 173-194.

6. Chen, Z., et al., Multicarboxylic hyperbranched polyglycerol modified SBA-15 for the adsorption of cationic dyes and copper ions from aqueous media. Applied Surface Science, 2012. 258(13): p. 5291-5298.

7. Li, M., et al., Methotrexate-conjugated and hyperbranched polyglycerol-grafted Fe(3)O(4) magnetic nanoparticles for targeted anticancer effects. Eur J Pharm Sci, 2013. 48(1-2): p. 111-20.

8. Ahn, C.H., J.-D. Jeon, and S.-Y. Kwak, Photoelectrochemical effects of hyperbranched polyglycerol in gel electrolytes on the performance of dye-sensitized solar cells. Journal of Industrial and Engineering Chemistry, 2012. 18(6): p. 2184-2190.

9. Mamiński, M.Ł., et al., Fast-curing polyurethane adhesives derived from environmentally friendly hyperbranched polyglycerols – The effect of macromonomer structure. Biomass and Bioenergy, 2011. 35(10): p. 4461-4468.

10. Mamiński, M.ł., M. Czarzasta, and P. Parzuchowski, Wood adhesives derived from hyperbranched polyglycerol cross-linked with hexamethoxymethyl melamines. International Journal of Adhesion and Adhesives, 2011. 31(7): p. 704-707.