通过对聚乙二醇端羟基烯丙基化及硅氢化加成反应,将疏水性有机硅基团接枝到亲水的聚乙二醇链段两端,得到有机硅接枝单元数量不同的两种线形-枝状两亲聚合物,用NMR、FTIR对其结构进行了表征,并评价了其表面活性。两种聚合物具有良好的表面活性,其临界聚集浓度(CAC)值分别为5.13×10-4mol/L和4.83×10-5mol/L,γCAC值分别为32.48 m N/m和32.21 m N/m。此外,该聚合物水溶液的表面张力-浓度曲线呈现"两段式"变化,说明聚合物分子在空气/水表面上有构象变换过程,而聚合物PEG链段、含硅枝状结构将显著影响吸附层中聚合物的分子构象。 相似文献
The synthesis of some novel ABA block copolymers is reported. The block A is a PPO while the block B is a random copoly(aryl ether sulfone), synthesized with three different molecular weights. The block copolymers were obtained by a two step procedure consisting on the functionalization of the random copoly(aryl ether sulfone) followed by a condensation with PPO. Spectroscopic techniques (1H NMR and 13C NMR) were used to characterize the polymers obtained from each step. The NMR data proved the complete conversion of amino groups after the first reaction step and gave some useful insights on the completion of the second step. Copolymer formation is supported by a comparison of the thermal behavior of the block copolymers with respect to the physical blends of the two homopolymers. DSC and DMA analyses showed double glass transitions for the physical blends which could be related to the immiscibility of the two homopolymers, while, in contrast, the block copolymer showed single glass transition. Blends of ABA triblock copolymer/PPO and of ABA triblock/copoly(arylen ether sulfone)s were also prepared. These blends, tested by DSC, showed a good level of compatibility of the ABA copolymer with its singular constituents.
SBS nanocomposites based on a SBS triblock copolymer containing different weight fractions of a commercial Cloisite 20A organoclay were prepared by melt‐processing. Extensive electron microscopy as well as WAXS and static tensile and tensile creep tests were used to evaluate the resulting morphological and mechanical properties of the nanocomposites. The nanocomposite morphology is characterized by a combination of intercalated and partly exfoliated clay platelets with occasional clay aggregates present at higher clay contents; nanocomposite features that are reflected by the results of both the static tensile as well as the tensile creep tests at room temperature. For this particular thermoplastic elastomer nanocomposite system, well dispersed nanoclays lead to an enhanced stiffness and ductility; effects that induce promising improvements in nanocomposite creep performance.
The properties of segmented‐copolymer‐based H‐bonding and non‐H‐bonding crystallisable segments and poly(tetramethylene oxide) segments were studied. The crystallisable segments were monodisperse in length and the non‐hydrogen‐bonding segments were made of tetraamidepiperazineterephthalamide (TPTPT). The polymers were characterised by DSC, FT‐IR, SAXS and DMTA. The mechanical properties were studied by tensile, compression set and tensile set measurements. The TPTPT segmented copolymers displayed low glass transition temperatures (Tg, ?70 °C), good low‐temperature properties, moderate moduli (G′ ≈ 10–33 MPa) and high melting temperatures (185–220 °C). However, as compared to H‐bonded segments, both the modulus and the yield stress were relatively low.
Summary: Novel block copolymers containing aromatic polyamide (aramid) and fluoroethylene segments were synthesized by a two‐step solution polycondensation. This synthetic method could control the chain‐length of aramid segments and these copolymers could have high structural regularity. The number‐average molecular weight ( ) of one of these polymers is over 2.0 × 104. Incorporating fluoroethylene segments improves the solubility of the resulting polymer compared with conventional aramids.
The synthesis of the fluoroethylene‐aramid block copolymers. 相似文献
