10302 Macromolecules, Vol. 43, No. 24, 2010
Rutherglen et al.
Project-Based Learning Partnership Program at Clarkson Uni-
versity, funded by the NSF (Program # DGE-0338216), and the
McNair Program at Clarkson University for financial support.
We also thank the US Army Research Office for a DURIP grant
(#W911NF-08-1-0524) for funding the purchase of a DMA.
Supporting Information Available: Plot of integration val-
ues for H NMR spectra and plots of DMA tensile data for
1
PNA/PETMP/EGDT polyanhydrides networks. This material
References and Notes
(1) Duncan, R.; Ringsdorf, H.; Satchi-Fainaro, R. Adv. Polym. Sci.
2006, 192, 1–8.
(2) Finne-Wistrand, A.; Albertsson, A.-C. Annu. Rev. Mater. Res.
Figure 7. Compressive stress-strain plots of polyanhydrides made
by thiol-ene polymerizations (reactions 3-5, Table 1). 4-Pentenoic
anhydride:pentaerythritol tetrakis(3-mercaptopropionate):3,6-dioxa-
1,8-dithiooctane (PNA:PETMP:EGDT) functional group ratios
(a) 1:1:0, (b) 1:0.75:0.25, and (c) 1:0.50:0.50.
2006, 36, 369–395.
€
(3) Gopferich, A.; Tessmar, J. Adv. Drug Delivery Rev. 2002, 54,
911–931.
(4) Katti, D. S.; Lakshmi, S.; Langer, R.; Laurencin, C. T. Adv. Drug
Delivery Rev. 2002, 54, 933–961.
(5) Kumar, N.; Langer, R.; Domb, A. J. Adv. Drug Delivery Rev. 2002,
54, 889–910.
(6) Heller, J. Biomaterials 1990, 11, 659–665.
(7) Heller, J.; Barr, J. Biomacromolecules 2004, 5, 1625–1632.
(8) Heller, J.; Barr, J.; Ng, S. Y.; Schwach-Abdellauoi, K.; Gurny, R.
Adv. Drug. Delivery Rev. 2002, 54, 1015–1039.
(9) Hill, J. W. J. Am. Chem. Soc. 1930, 52, 4110–4114.
(10) Hill, J. W.; Carothers, W. H. J. Am. Chem. Soc. 1932, 54,
1569–1579.
can be related to the higher rigidity and cross-link density in
samples containing less EGDT. Also, greater hysteresis is ob-
served in samples with more EGDT, an indication of the elasticity
and deformation resistance of samples with less (no) EGDT. The
75% EGDT sample failed most likely due to the very low cross-
link density and the soft, adhesive properties at 37 °C.
(11) Conix, A. In Macromolecular Syntheses; Wiley: New York, 1963;
Vol. 2, pp 95-99.
(12) Tarcha, P. J.; Su, L.; Baker, T.; Langridge, D.; Shastri, V.; Langer,
R. J. Polym. Sci., Part A: Polym. Chem. 2001, 39, 4189–4195.
(13) Langer, R. Acc. Chem. Res. 2000, 33, 94–101.
(14) Uhrich, K. E.; Cannizzaro, S. M.; Langer, R.; Shakesheff, K. M.
Chem. Rev. 1999, 99, 3181–3198.
(15) Anseth, K. S.; Shastri, V. R.; Langer, R. Nature Biotechnol. 1999,
17, 156–159.
(16) Gao, J.; Niklason, L.; Zhao, X.-M.; Langer, R. J. Pharm. Sci. 1998,
87, 246–248.
(17) Uhrich, K. E.; Gupta, A.; Thomas, T. T.; Laurencin, C. T.; Langer,
R. Macromolecules 1995, 28, 2184–2193.
(18) Tamada, J. A.; Langer, R. Proc. Natl. Acad. Sci. U.S.A. 1993, 90,
552–556.
(19) Domb, A. J.; Mathiowitz, E.; Ron, E.; Giannos, S.; Langer, R.
J. Polym. Sci., Part A: Polym. Chem. 1990, 29, 571–579.
(20) Domb, A. J.; Langer, R. J. Polym. Sci., Part A: Polym. Chem. 1987,
25, 3373–3386.
(21) Shieh, L.; Tamada, J.; Chen, I.; Pang, J.; Domb, A.; Langer, R.
J. Biomed. Mater. Res. 1994, 28, 1465–1475.
Conclusions
The synthesis, via thiol-ene polymerization, and physical and
thermal characterization of photoinitiated cross-linked degrad-
able polyanhydrides were carried out. The addition of thiol to the
anhydride was observed but takes place at a much slower rate
than photoinitiated thiol-ene polymerization. However, in poly-
merizations using a stoichiometric amount of thiol and ene, this
side reaction results in a slight excess of ene functionality. The
thermomechanical properties, including the glass transition tem-
perature (Tg) as well as tensile and compressive modulus, of the
cross-linked material were studied using DMA. The Tg values
ranged from -15 to approximately -50 °C. As often seen in
thiol-ene cross-linked networks, the tan δ peaks appeared quite
narrow. The Young’s and compressive modulus measurements
confirm that these types of networks are a soft rubber-like
material and become softer as the cross-linking density is re-
duced. The hydrophobicity/hydrophilicity of these networks was
analyzed by contact angle measurements. The four compositions
of polyanhydrides studied possess surfaces that are moderately
hydrophobic, with contact angle averages ranging from approxi-
mately 82° to 92°. These results are similar to previously
studied polyanhydrides which were also found to be hydrophobic
materials.
(22) Prudencio, A.; Schmeltzer, R. C.; Uhrich, K. E. Macromolecules
2005, 38, 6895–6901.
(23) Ben-Shabat, S.; Abuganima, E.; Raziel, A.; Domb, A. J. J. Polym.
Sci., Part A: Polym. Chem. 2003, 41, 3781–3787.
(24) Teomim, D.; Domb, A. J. Biomacromolecules 2001, 2, 37–44.
(25) Determan, A. S.; Graham, J. R.; Pfeiffer, K. A.; Narasimhan, B.
J. Microencapsulation 2006, 23, 832–843.
This work demonstrates that thiol-ene polymerization can be
used to produce cross-linked anhydride-containing materials that
have been previously shown to undergo the oft-preferred surface-
eroding characteristic. The step growth mechanism involved with
thiol-ene polymerization allows for the possibility of a variety of
thiol and ene monomers to be used in combination, thus giving
the freedom to tune the rates and properties of the final material
in order to suit many applications. Because of the elastic and
adhesive-like characteristics of the polymers studied here, some
applications for these thiol-ene/polyanhydrides could be in
controlled drug delivery, tissues adhesives, and wound closure.
(26) Kipper, M. J.; Narasimhan, B. Macromolecules 2005, 38, 1989–
1999.
(27) Kipper, M. J.; Wilson, J. H.; Wannemuehler, M. J.; Narasimhan,
B. J. Biomed. Mater. Res., Part A 2006, 76A, 798–810.
(28) Lopac, S. K.; Torres, M. P.; Wilson-Welder, J. H.; Wannemuehler,
M. J.; Narasimhan, B. J. Biomed. Mater. Res., Part B 2009, 91B,
938–947.
(29) Torres, M. P.; Determan, A. S.; Anderson, G. L.; Mallapragada,
S. K.; Narasimhan, B. Biomaterials 2007, 28, 108–116.
(30) Torres, M. P.; Vogel, B. M.; Narasimhan, B.; Mallapragada, S. K.
J. Biomed. Mater. Res., Part A 2006, 76A, 102–110.
(31) Ulery, B. D.; Phanse, Y.; Sinha, A.; Wannemuehler, M. J.;
Narasimhan, B.; Bellaire, B. H. Pharm. Res. 2009, 26, 683–690.
(32) Brem, H.; Piantadosi, S.; Burger, P. C.; Walker, M.; Selker, R.;
Vick, N. A.; Black, K.; Sisti, M.; Brem, S.; Mohr, G.; Muller, P.;
Morawetz, R. Lancet 1995, 345, 1008–1012.
Acknowledgment. We thank the Department of Chemistry
and Biomolecular Science at Clarkson University, the Center
for Advanced Materials Processing at Clarkson University, a
New York State Center for Advanced Technology, the GK-12
(33) Shipp, D. A.; McQuinn, C. W.; Rutherglen, B. G.; McBath, R. A.
Chem. Commun. 2009, 6415–6417.