2324 Full Paper wileyonlinelibrary.com Macromolecular Chemistry and Physics DOI: 10.1002/macp.201300381 Novel Bisphosphonated Methacrylates: Synthesis, Polymerizations, and Interactions with Hydroxyapatite Zeynep Sarayli Bilgici, Sebnem Begum Turker, Duygu Avci* Five novel methacrylates containing either bisphosphonate (1 and 2), bisphosphonic acid (3), carboxylic acid (4), or both bisphosphonic and carboxylic acid together (5), are synthesized. The monomers 1 and 2 are synthesized by the reactions of tetraethyl 1-hydroxyethane-1,1- diyldiphosphonate with ethyl α-bromomethacrylate and tert- butyl α-bromomethacrylate; the same procedure fails with tetraethyl hydroxy(phenyl)methylenediphosphonate. 1 is con- verted to 3 by hydrolysis with trimethylsilyl bromide (TMSBr), and 2 is converted to 4 by hydrolysis with trifluoroacetic acid (TFA). Monomer 5 is obtained by hydrolysis of 2 first with TMSBr and then with TFA. The hydrolytic stability, the proper- ties of the copolymerizations with commercial dental mono- mers, and HAP interactions make these monomers promising candidates for dental adhesives. Z. S. Bilgici, Prof. D. Avci Department of Chemistry, Bogazici University, 34342, Bebek, Istanbul, Turkey E-mail: avcid@boun.edu.tr Dr. S. B. Turker Faculty of Dentistry, Marmara, University, 34365, Nisantasi, Istanbul, Turkey fulfilled using variously designed methacrylates and methacrylamides with sufficient reactivity. The adhesion of monomers on tooth tissue is mainly due to chemical bonds, such as covalent or ionic bonds, resulting from reaction of acidic and chelating groups with hydroxyapa- tite (HAP) and physical bonds due to van der Waals forces, London dispersion forces, hydrogen bonding, or charge-transfer complexes. [5] According to the “adhesion– decalcification” concept of Yoshida et al., [6,9] the bonding performance of the adhesives depends on the chemical stability of the monomer-Ca salts formed with the inter- action of the acid monomer and HAP. Therefore, the struc- ture of the acid monomer is very important and small differences such as polarity in the monomer structures cause significant differences in their adhesive perfor- mance. For example, while 4-META and Phenyl-P deposit unstable calcium salts due to dissolution, MDP forms hydrolysis-resistant calcium salts due to its hydrophobic decyl group. Therefore, extensive research has been con- ducted to develop new monomers with acid functional groups, which may strongly bond to HAP. For example, bis- phosphonates, structural analogues of naturally existing pyrophosphate with increased chemical and enzymatic stability and strong affinity for HAP, can be incorporated 1. Introduction Monomers functionalized with acid groups such as dihydrogen phosphates, carboxylic and phosphonic acids can be utilized in dental materials such as self- adhesive resin cements and self-etching adhesives. [1–4] The currently used examples of acid monomers are 4-methacryloxyethyl trimellitic anhydride (4-META), 2-methacryloxyethyl phenyl hydrogen phosphate (Phenyl-P), 10-methacryloxydecyl dihydrogen phosphate (MDP), and 2,4,6-trimethylphenyl 2-[4-(dihydroxyphosphoryl)-2-oxa- butyl]acrylate (MAEPA)]. Some of the properties desired for adhesive monomers are: i) high rate of free-radical homopolymerization or copolymerization with the other monomers in the adhesive, ii) ability to form strong bonds with tooth tissue, iii) sufficient stability both in storage and in the mouth. The first requirement can be Macromol. Chem. Phys. 2013, 214, 2324−2335 © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim