Biocompatible Phosphorus-based Monomers for Radical Polymerization
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1235-RR03-32
Biocompatible Phosphorus-based Monomers for Radical Polymerization C. Dworak,1 C. Heller,1 F. Varga,2 and R. Liska1 1
Institute of Applied Synthetic Chemistry, Vienna University of Technology, Vienna, Austria
2
Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA
Trauma Centre Meidling, 4th Medical Department, Hanusch Hospital, Vienna, Austria ABSTRACT Novel biocompatible and biodegradable monomers based on phosphorus-containing vinyl esters and vinyl carbamates for radical photopolymerization were prepared. By photoDifferential Scanning Calorimetry (photo-DSC) the reactivity of the mono-, di- and trifunctional monomers was investigated. Furthermore, their cytotoxicity, mechanical properties and hydrolytic degradation behavior were evaluated, aiming at a future application of our compounds in the biomedical area. INTRODUCTION Photoinduced radical polymerization presents a powerful tool to produce films and coatings within the fraction of a second. This method delivers many advantages for industrial applications like high curing speed, environmentally friendly production, as well as time, cost and space efficiency. Due to such excellent features, radical photopolymerization finds more and more attention also in other fields of application, such as biomedical sciences. Thus, phosphoruscontaining polymers gained increasing interest as biopolymers due to their excellent properties.[1,2] To obtain biocompatible and degradable polymers we used the vinyl ester functionality, which is known to have a low cytotoxicity due to the low tendency towards Michael addition reactions with amino groups in proteins. Additionally, a non-toxic poly(vinyl alcohol) backbone is released after degradation [3]. During this work, various phosphorus-based vinyl esters but also vinyl carbamates were synthesized as shown in Figure 1. O H N O Mono-
EtO
P
O
V1
EtO
OEt
O
P
C1
O
EtO
P
OEt OEt O
O O
O O
P
O
V2
O
Tri-
EtO
O
O
P OEt O
O Di-
O
O
P
O
C2
O N H NH
V3 O
O
O
Figure 1. Structures of investigated phosphorus-based monomers
E1
Photo-DSC was applied to determine the monomer reactivity and the double bond conversion (DBC) was measured by ATR-IR spectroscopy in combination with PeakFit analysis (PeakFit SSI, V4.12). By combination of both methods the theoretical heats of polymerization could be calculated for our monomers. Additionally, cytotoxicity on osteoblast cells was evaluated by cell viability and expression of alkaline phosphatase (ALP). By nanoindentaion experiments values for the Young´s Modulus and hardness of polymer disks of E1 with various amounts of V2 as crosslinker were obtained. Finally, hydrolytic degradation behavior of the crosslinked polymers of V2, C2 and V3 was tested in alkaline and acidic media at 37°C. EXPERIMENTAL DETAILS Monomers were synthesized according to procedures described in literature [4]. The phosphoformate E1 was prepared by the Michaelis-Arbuzov reaction of triethylphosphite and chlorovinyl formate. For the preparation of C1
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