pubs.acs.org/Macromolecules Published on Web 03/17/2010 r 2010 American Chemical Society Macromolecules 2010, 43, 3277–3285 3277 DOI: 10.1021/ma902798b Novel Thermally Cross-Linkable Poly[(arylenedioxy)(diorganylsilylene)]s Based on Curcumin: Synthesis and Characterization Indraneil Mukherjee, † Kerry Drake, †,‡ David Berke-Schlessel, † Peter I. Lelkes, § Jui-Ming Yeh, ) and Yen Wei* ,†, ) † Department of Chemistry, Drexel University, Philadelphia, Pennsylvania 19104, ‡ Greene Tweed & Co., 2075 Detwiler Road, Kulpsville, Pennsylvania 19443, § School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, and ) Department of Chemistry, Chung Yuan Christian University, Chunli, Taiwan 32023 Received December 18, 2009; Revised Manuscript Received March 6, 2010 ABSTRACT: Curcumin has attracted much attention due to its chemopreventive and anti-inflammatory properties. Here we describe the synthesis of poly[(arylenedioxy)(diorganylsilylene)]s via polycondensation between curcumin and various diorganodichlorosilanes. These novel polymers incorporate the β-diketone unit of curcumin as well as the Si-O bond in the backbone. The polymer structure was characterized by means of 1 HNMR, FTIR, and elemental analysis, while GPC results showed high molecular weights. Preliminary cell culture results suggest lack of cytotoxicity, which is important for potential applications such as implant and scaffold materials. The T g s of these polymers are in the 24 to 131 °C range, tunable by altering the pendant organic groups. The un-cross-linked polymers are stable at 250 °C in air. The presence of vinyl groups in the backbone also allows the possibility for thermal cross-linking. DSC and rheology data demonstrate that the materials can cross-link at a temperature above 200 °C which suggests the feasibility of melt processing these polymers via a technique wherein a low viscosity polymer is made to flow into a heated mold where it cross-links over time and becomes a rigid thermoset material. 1. Introduction Turmeric is a dried, ground rhizome of Curcuma longa,a perennial herb found commonly in Southeast Asia. 1 The use of this yellow powder as a spice and coloring agent in Indian cooking and as a therapeutic agent in traditional Indian and Chinese medicine has been known for centuries. Turmeric con- tains phenolic compounds called curcumoids that impart the characteristic yellow color. 2 Of these, curcumin [1,7-bis(4-hydroxy- 3-methoxyphenyl)-1,6-heptadiene-3,5-dione], as the principle ingredient, accounts for about 77%; demethoxycurcumin for about 17% and bisdemethoxycurcumin about 3%. 3 All three curcumoids are diphenolic compounds. In recent years, a large amount of experimental data has established the chemopreventive and chemotherapeutic proper- ties of curcumin, 4-9 which has led to efforts toward drug development. 10,11 Jacob et al. 12 reported that the anti-inflamma- tory function of curcumin is perhaps one of its most important properties. Kohli et al. 13 and Chainani-Wu 14 published excellent reviews on the anti-inflammatory activity of curcumin. The anti- inflammatory properties of curcumin can be attributed to a large extent to its ability to inhibit the activation of NFK-β. 15-17 Curcumin has also been demonstrated to be effective against other diseases and biological conditions ranging from cystic fibrosis 18 and Alzheimer’s disease 19 to malaria. 20 The promising biological effects of curcumin have led to a host of other review articles on the subject. 3,21-23 In the field of polymer chemistry, curcumin has been used as an environment friendly and economical photoinitiator. 24,25 Suwan- tong et al. 26 and Gopinath et al. 27 reported the fabrication of curcumin containing electrospun cellulose acetate mats and curcumin incorporated collagen films, respectively, exploiting the anti-inflammatory function of curcumin. Raja et.al employed click chemistry to prepare a PAMAM dendrimer curcumin conjugate. 28 In addition, poly(vinyl chloride) was functionalized with curcumin by employing a nucleophilic substitution reaction to prepare a polymer that undergoes fluorescent quenching. 29 Curcumin was also used as a colorant for silicone based elasto- mers. 30 To the best of our knowledge, there has been only one report on the synthesis of a polymer using curcumin as a monomer. In this work, Matsumi et al. 31 synthesized polyesters by polycondensation of acid chlorides with the phenolic group of curcumin. On the other hand, polysiloxanes (aka silicones) are often prepared by reacting dialkyl or diaryl dichlorosilanes with water, resulting in the elimination of hydrogen chloride. 32 The strength of Si-O bond imparts substantial thermal stability whereas its length provides greater flexibility and oxygen permeability to these materials. 33 Polysiloxanes are known to be highly biocom- patible materials. 34,35 Srividhya et al. 36 have attributed the super- ior biocompatibility of polysiloxanes to their low chemical reactivity, hydrophobicity and low surface energy. These materi- als have found applications in contact lenses, 37 artificial heart valves, 38 medical adhesives, 39 etc. However, polysiloxanes, espe- cially polydimethylsiloxane lack thermal rigidity and tend to exhibit “cold flow”, especially at higher temperatures. 40,41 Further, thermally induced depolymerization is a limitation. 42 Addition of aromatic rings to the backbone provides rigidity to the structure and overcomes these drawbacks. 43 Copolymeriza- tion with curcumin accomplishes the addition of aromatic rings in the polymer backbone. In this article, we present the synthesis of a series of poly- [(arylenedioxy)(diorganylsilylene)]s through a polycondensation *Corresponding author. Telephone: 215-895-2650. Fax 215-895-1265. E-mail: weiyen@drexel.edu.