The photolytic addition of thiols or thiolacetic acid to olefinic groups at the surfaces of syndiotadic 1,2-polybutadiene (PBD) provided polymer surfaces bearing sulfide or thioacetate groups. Ethanolysis cleaved these thioacetate groups t o give the corresponding thiols. The product surfaces have been characterized by attenuated total reflectance infrared (ATR-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angles of water. Evaporated films of copper and of gold adhered to surfaces of sulfur-functionalized polymers but not to the unfmctionalized polymers in tape-peel tests. Quantitative adhesion experiments were performed using a 180" peel test with these surface-modified derivatives of PBD (and with the unmodified polymer) heated under pressure against copper foil substrates, and the limiting values of peel strength in these systems were related to the identity of the interfacial functionality in an understandable way. The rate in growth of adhesion was not limited by thermal reconstruction of the polymer surface. Mechanical studies of modified and unmodified samples of PBD indicated that the observed differences in adhesion are not due to changes in the bulk properties of the polymer.

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6831cooperative complex calculated with the parameters tb = -4500 cal/mol, So = 1.6 X IO4, and u = 3.2 X For illustrative purposes, we may define an entropy of nucleation, AS, = R In u = -1 1.4 eV and an entropy of bond formation, ASb R In So = -17.3 eu. The model with N = 5 and these parameters obviously generates a cooperative melting curve that closely mimics the transition reported here (Figures 7,8, and 10). Within the spirit of this model, the parameters do not violate reasonable ideas of the strength of the entropy change for localizing opposing segments of the interface. (58) The fraction of broken bonds is defined as ( ( N ( 0 ) ) -( N ( T ) ) ) / ( N -( 0 ) ) , where (N(T)) is the average number of bonds and is given by eqs 16-93 of ref 57 and N(0) 5 N -1 in the model as formulated (ref 57). We have explored a range of N and find this makes no difference to the qualitative features of this approach. However, the magnitudes of cb, ASSb, and ASn decrease with increasing N .Future work will address such features as the structural differences that cause the high-temperature forms of the complex to exhibit quenching whereas the low-temperature form@) do not. It will further seek a realistic picture of the interfacial interactions in both types of forms, as well as a kinetic mechanism that embodies the ideas proposed here. Acknowledgment.We acknowledge research support from the NSF (Grant DMB 8907559 to B.M.H.), the N I H (Grants HL13531 to B.M.H.; GM 33806 to M.K.J.; GM 29001 and G M 19121 to E.M.), and the MRC of Canada (Grant MT-1706 to M.S.). We are indebted to Profs. John Torkelson and Laszlo Lorand for the gracious use of their spectrofluorimeters and to Drs. Sten Wallin, Eric Garber, and Thomas Luntz for helpful discussions. Abstract: Natural abundance 13C and I5N solid-state NMR experiments were performed on undoped and doped samples of polyazine, (-N=C(R)-C(R)=N-),,The topology of the polymer requires that doping-induced charge carriers must be either polarons (radical cations) or bipolarons (dications). Magnetic susceptibility measurements shows that the iodine-doped polymers are diamagnetic, so the charge carriers must be bipolarons. The specific bipolaron charge carrier in polyazines has been identified; the nitrogens bear the charge primarily in the form of a nitrenium cation. This is the first report of a nitrenium cation detected by I5N solid-state NMR spectroscopy. Independent of the substitution of the polyazine, R = H or CH3, the same charge carrier is present.

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