New Broom Fiber (Spartium junceum L.) Derivatives: Preparation and Characterization ROBERTA CASSANO,* ,† SONIA TROMBINO, † ERMELINDA BLOISE, † RITA MUZZALUPO, † FRANCESCA IEMMA, † GIUSEPPE CHIDICHIMO, § AND NEVIO PICCI † Departments of Pharmaceutical Sciences and Chemistry, University of Calabria, Rende (CS), Italy In the past decade interest in biopolymers has increased. Attempts were made to prepare new composite systems from biopolymers by binding different synthetic polymers to a biopolymer backbone. This paper reports the synthesis and characterization of derivatized broom fibers to prepare composites with either degradability or fireproofing properties. Synthetic strategies are described for the introduction of polymerizable functional groups or fluorine atoms on the glucose of cellulose chains of broom. The fibers containing polymerizable groups were copolymerized with dimethylacrylamide and styrene and, after that, investigated by optical polarizing microscopy (OPM) and scanning electron microscopy analysis (SEM). The materials containing fluorine were submitted to thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for the purpose of verifying the fireproofing. Such derivatized biomaterials could be successfully used for applications in agriculture and in the packaging area. KEYWORDS: Broom fibers; functionalization; fluorine; agriculture; packaging; polymer INTRODUCTION Over the past decade, polymer composites reinforced with natural fibers have received ever-increasing attention, from both academic and industry points of view. The main advantages that they have are low cost and high specific mechanical properties that allow their usage as a good, renewable alterna- tives to the most common synthetic reinforcement, such as glass fibers, which are not biodegradable (1–3). There is a wide variety of different natural fibers applicable as reinforcement or fillers. Cotton, jute, and flax are the vegetable fibers most commonly used to reinforce polymers such as polystyrene (4, 5), polyesters (6), polyolefins (7, 8), and epoxy resins (9, 10) due to their availability and properties. Broom is a further important fiber with numerous advantages, abundantly available, and biode- gradable; because it is made of cellulose, on combustion, broom fibers do not generate toxic gases and are able to produce materials by combination with plastic mixtures. These fibers, known as vermenes, show extraordinary traction resistance and flexibility. Broom fiber and generally vegetable fiber composites provide improved specific or synergistic characteristics not obtainable by any of the original components alone and can be highly cost-effective materials for a number of applications such as those for the food industry. Besides the advantages mentioned above, the fiber composites possess also some disadvantages such as their poor compatibility with a hydrophobic polymer matrix, the high affinity of natural fibers toward water, and their relatively poor thermal stability. This leads to the formation of weak interfaces that result in poor mechanical properties of the composites. For such reason the idea to link halogenated or polymerizable molecules to broom fibers by covalent bond (Figure 1) to produce poorly flammable materials and to improve fiber strength and fiber/matrix adhesion in fiber composites was conceived (11). These systems could be applied in agriculture and in the packaging area. In this paper, we report the synthesis and characterization of broom fiber derivatives obtained by esterification with molecules containing fire retardant or poly- merizable groups. Trifluoroacetic acid and heptafluorobutyric acid were used as efficient flame retardants in substitution of ozone-depleting and toxic substances containing chlorine and bromine (12). To obtain renewable plastic fibers, they were initially reacted with acryloyl chloride, 4-vinylbenzyl chloride, and 4-vinylbenzoyl chloride. Oxidized broom fibers were suc- cessfully used to prepare an amide-linked polymerizable con- jugate with 4-aminomethyl styrene chlorohydrate. The obtained materials were characterized by Fourier transform infrared (FT- IR) spectroscopy; the degree of substitution (DS) of ester, ether, and amide derivatives was determined by titration. Moreover, the fireproofing of materials containing fluorine was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) measurement. The broom fibers derivatized with polymerizables groups were copolymerized with dimethy- lacrylamide and styrene, both in equimolecular amounts or with * Corresponding author (telephone +39 984493296; fax +39 984493163; e-mail roberta.cassano@unical.it). † Department of Pharmaceutical Sciences. § Department of Chemistry. J. Agric. Food Chem. 2007, 55, 9489–9495 9489 10.1021/jf071711k CCC: $37.00  2007 American Chemical Society Published on Web 10/19/2007