STUDIES OF POLYMER COMPATIBILITY BY NONRADIATIVE ENERGY TRANSFER

The excitation energy of a donor can be transferred to an acceptor when the emission spectrum of the donor overlaps the absorption spectrum of the acceptor. Polymers were prepared containing the comonomers, 2-(N-carbazolyl)ethyl methacrylate and 9-anthryl methyl methacrylate as fluorescence donors and acceptors, respectively. The mutual interpenetration of the polymer chains carrying the donor and the acceptor led to a sharp increase of excitation energy transfer characterized by the relative emission intensities at 347 nm and 413 nm, the emission maxima of the carbazolyl and the anthryl chromophores, when the system was irradiated at 296 nm. The critical transfer distance R(,0) = 2.7 nm to 2.9 nm was calculated from spectroscopic parameters. However R(,0) = 3.6 nm was obtained from the quenching of the donor fluorescence at increasing acceptor concentrations when 2-(N-carbazolyl)ethyl acetate and 9-anthryl methyl acetate were incorporated in polymer films.; The polymer blends of poly(styrene co acrylonitrile) with poly(methyl methacrylate) were studied by energy transfer method. The range of compatibility indicated by the fluorescence technique was similar, but slightly narrower than estimated from the optical clarity. The efficiency of energy transfer was decreased when the films were heated to 145(DEGREES)C and quenched at -78(DEGREES)C.; Polystyrene was modified by copolymerization with methacrylic acid which was expected to hydrogen bond with poly(methyl methacrylate). However, incompatible polymer pairs were found for all compositions of poly(styrene co methacrylic acid) with poly(methyl methacrylate).; Polymer blends which have no specific interaction between any two components are predicted to exhibit compatibility when the solubility parameters of the components are matched. Blends of poly(ethyl methacrylate) or poly(propyl methacrylate) with methyl methacrylate - butyl methacrylate copolymers have maximum compatibility when the mean length of the methacrylate copolymer side chains matches the length of the side chains in the methacrylate homopolymer. This experiment also shows that the fluorescence energy transfer technique is more sensitive than the optical method.; On the basis of polarity considerations, polymer blends of poly(butyl methacrylate co acrylonitrile) with poly(methyl methacrylate), poly(styrene co acrylonitrile) with poly(ethyl methacrylate) and poly(styrene co methyl methacrylate) with poly(propyl methacrylate) should be compatible in some ranges of copolymer composition. No compatible pair was found using the fluorescence technique. However, in some particular region of copolymer composition, these polymer - copolymer pairs exhibited a maximum energy transfer.; The polarities of poly(p-chlorostyrene) and poly(styrene co acrylonitrile) should be matched in some range of copolymer composition. Not only were these blends found to be incompatible, but the efficiency of energy transfer hardly changed with copolymer composition.