Novel aliphatic poly(ester−amide)s with a periodic sequential structure consisting of ester and amide groups were synthesized by two-step polycondensation reactions using adipate, butane-1,4-diamine, and linear diols with different chain lengths, ranging from 3 to 6 methylene groups. Effects of the monomeric structure and sequential length of ester units on the thermal properties and crystalline structure of the obtained periodic copolymers were determined by means of differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). On the basis of DSC measurements, the melting temperatures of the periodic copolymers were higher than those of homopolyesters consisting of the same ester units and tended to increase with an increase in amide content. The copolymers from adipate, butane-1,4-diol, and butane-1,4-diamine had especially high thermal stability compared with the poly(tetramethylene adipate) homopolyester, and the melting temperatures detected were above 200 °C. The X-ray diffraction patterns of periodic copolymers were variable with some copolymers displaying patterns similar to homopolyesters while other copolymers had diffraction patterns that were very different than the homopolyester, dependent on both the monomeric structure of the ester units and the sequential length of the ester units. The formation of different chain packing structures compared to homopolyesters induced the remarkable enhancement of thermal stability, suggesting that molecular chain arrangements based on the intermolecular hydrogen bond interactions play a decisive role in the formation of a thermally stable crystalline region of periodic copolymers and that the formation of intermolecular hydrogen bonds is strongly dependent on both the monomeric structure of ester units and the sequential length of ester units. Furthermore, the effects of annealing treatment on the thermal properties and molecular chain arrangements of periodic copolymers were investigated.
Vinyl addition copolymerization of norbornene with norbornene derivatives bearing siloxane substituent, three arm-, cyclicand phenyl-siloxane groups, was realized in the presence of the binary Ni(acac) 2 /B(C 6 F 5 ) 3 system. The resulting copolymers show good solubility in common organic solvents and possess a very high grass transition temperature between 265 and 360 C, depending on the content and structure of the siloxane groups. The incorporation of siloxane groups linked to the polymer chain results in a significant increase in the mechanical flexibility of the corresponding films. Furthermore, the gas permeability is also dependent on the content and structure of the siloxane groups, and the films obtained for the polymers with three arm-siloxane group (-Si(OSiMe 3 ) 3 ) display high oxygen permeability in the range of 39 to 239 Barrer.KEY WORDS: Polynorbornene / Siloxane Substituent / Copolymerization / Nickel Catalyst / Norbornene can be polymerized by three different methods: ring opening metathesis polymerization (ROMP), cationic or radical polymerization, and vinyl addition polymerization. 1Among these polymers, addition-type poly(norbornene), presenting the rigid bicyclic structure, is recently attracting strong interest in optical and opto-electronic device applications because of high optical transparency, low birefringence, very high glass transition temperature and low dielectric constant. However, poor solubility in common organic solvents and mechanical brittleness are serious disadvantages for the processing of the polymer materials. These problems can be improved markedly by copolymerizing a small amount of functional norbornene derivatives.So far, many types of poly(norbornene)s with functional groups have been prepared. [2][3][4][5][6][7][8][9][10][11][12][13] Heitz et al. 2,3 investigated the addition-type copolymerizations of norbornene with norbornene carboxylic acid esters, and found that the solubility of the copolymers and the thermal properties, such as glasstransition and decomposition temperatures, were dependent on the content as well as structure of the substituents. Risse et al. [4][5][6] came to the same conclusion by studying poly-(norbornene)s containing hydroxyl, carboxylic acid and ester. Goodall et al.7-9 and Grove et al. 10 prepared alkyl-or alkoxysilyl-substituted poly(norbornene)s, which showed improved mechanical toughness and adhesion to common substrate materials. On the other hand, Dorkenoo et al. 11and Finkelshtein et al.12 investigated the homopolymers of norbornene derivatives bearing alkyl or alkylsilyl substituents, and demonstrated that the chain length and the bulkiness of the substituents played a decisive role in the transport properties, such as gas permeability and permselectivity, for the polymeric membranes. These results show that the nature of substituent and the content in the main chain are an important factor for the regulation of the material properties.Poly(siloxane) is a class of polymers that has practical importance in the consumer and indus...
Four novel series of periodic copolymers composed of ester and amide units with the same carbon numbers were synthesized by two-step polycondensation reactions using adipate, linear aliphatic diols, and diamines with various chain lengths, ranging from 3 to 6 methylene groups. Effects of the comonomeric and sequential structures on the physical properties and crystalline structures were investigated for the obtained copolymer series by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and tensile testing. The thermal properties of obtained periodic copolymer series were found to be strongly dependent on both comonomeric and sequential structures, and the values showed remarkable differences between neighboring methylene numbers in the comonomer units. Such thermal behavior was strongly correlated to the wide-angle X-ray diffraction patterns, with some copolymers displaying patterns similar to homopolyesters, while other copolymers had diffraction patterns that were very different than the homopolyester, dependent on the comonomeric and sequential structures. These results suggest that the molecular chain arrangements and their intermolecular hydrogen bond interactions based on the ester-amide sequential structure play an important role in the formation of a thermally stable crystalline region. Furthermore, the mechanical properties of periodic copolymers were determined from the stress-strain curves of film samples.
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