Poly(ferrocenylmethyl acrylate), poly(ferrocenylmethyl methacrylate), and poly(ferrocenylethylene) have been prepared by AIBN-catalyzed, free-radical polymerization in benzene solution. Treatment of these polymers with strongly electron attracting compounds such as tetracyanoethylene, dichlorodicyanoquinone, and o-chloranil leads to poly(ferricinium) salts, or polymeric charge-transfer derivatives. The characterization of these polymers was carried out by kinetic studies, infrared, nuclear magnetic resonance, ultraviolet, and Mossbauer spectroscopy, as well as gel permeation chromatography and viscosity studies. Some of these studies must be

Communications to the Editor 105 Figure 4. Generalized retention curve for polypropylene using hexadecane probe (column C) O, melting curve, first series; , melting curve, second series.those obtained by other procedures is a further corroboration, as is the fact that the values of Tm are not decreased from the expected values for the polymers used. If there were any appreciable solution of the probe molecules in the crystalline regions, some depression of 7", would be anticipated.If further experiments verify this conclusion it would appear possible to use this phenomenon to construct a new definition of "order" in polymers. That is, an "ordered region" would be defined as a region impermeable to probe molecules which can permeate the "amorphous regions" of the polymer. The relation of values obtained using this method to those obtained by more conventional techniques using X-ray diffraction or density measurements must await further study in which all three methods are used on identical polymer samples. However it should be pointed out that this new method should in principle be sensitive to the presence of very small crystallites which cannot be detected by standard X-ray diffraction methods. Unlike the density method, the presence of voids or air bubbles should not affect the results either. However it has the disadvantage that the polymer must be in the form of a thin film in order to be studied. In spite of this, the simplicity of the method has much to commend it, and the additional information on thermodynamic interactions and on structural changes such as glass transitions which may be derived from the same data1,2 represent added features. In view of these considerations we suggest that the "molecular probe" technique will become a standard procedure in the study of melting transitions in macromolecules.

The benzene solution homopolymerization of vinylferrocene, initiated by azobisisobutyronitrile, gave a series of benzene‐soluble homopolymers. Thus, free‐radical copolymerization studies were performed with styrene, methyl acrylate, methyl methacrylate, acrylonitrile, vinyl acetate, and isoprene in benzene. With the exception of vinyl acetate and isoprene, which did not give copolymers with vinylferrocene under these conditions, smooth production of copolymers occurred. The relative reactivity ratios, r1 and r2, were obtained for vinylferrocene–styrene copolymerizations by using the curve‐fitting method for the differential form of the copolymer equation, by the Fineman‐Ross technique, and by computer fitting of the integrated form of the copolymer equations applied to higher conversion copolymerizations. In styrene (M2) copolymerizations, the curve‐fitting and Fineman‐Ross methods both gave r1 = 0.08, r2 = 2.50, while the integration method gave r1 = 0.097, r2 = 2.91. Application of the integration method to methyl acrylate and methyl methacrylate (M2) gave values of r1 = 0.82, r2 = 0.63; r1 = 0.52, r2 = 1.22, respectively. The curve‐fitting method gave r1 = 0.15, r2 = 0.16 for acrylonitrile (M2) copolymerizations. From styrene copolymerizations, vinylferrocene exhibited values of Q = 0.145 and e = 0.47.

Two novel ferrocene-containing monomers, ferrocenylmethyl acrylate, la (FMA), and ferrocenylmethyl methacrylate, lb (FMMA), have been synthesized. Both la and lb were copolymerized with styrene, methyl acrylate, methyl methacrylate, and vinyl acetate in benzene solutions initiated by azobisisobutyronitrile (AIBN) at 70°. Homogeneous copolymers were formed in each case, and the relative reactivity ratios of each copolymerization were determined. The values of n and r2 were:FMA (monomer l)-styrene = 0.02, r2 = 2.3; FMMA (monomer l)-styrene rr = 0.03, r2 = 3.7; FMA-methyl acrylate = 0.14, r2 = 4.46; FMMA-methyl acrylate = 0.08, r2 = 0.82; FMA-mefhyl methacrylate = 0.08, r2 = 2.9; FMMA-methyl methacrylate -0.12, r2 = 3.27; FMA-vinyl acetate r2 = 1.44, r2 = 0.46; and FMMAvinyl acetate r2 = 1.52, r2 = 0.20. While both FMA and FMMA are less reactive than other acrylates and methacrylates, they can be incorporated into copolymers which might have important commercial applications.

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