Deyue Yan

Brill transition in Nylon 10 12 investigated by variable temperature XRD and real time FT‐IR

Variable temperature X-ray diffraction (XRD) and real time Fourier transform infrared spectroscopy (FT-IR) were used to study the Brill transition of wekk crystallized Nylon 1012 samples. The experimental data demonstrate that Nylon 1012 undergoes Brill transition at about 120°C. IR spectra also show that a sequence of bands at 897 cm -1 , 986 cm -1 , 1165 cm -1 , 1189 -1 , 1224 cm -1 and 1338 cm -1 which are a-bands disappear abruptly during Brill transition.

Reverse atom transfer radical polymerization of methyl acrylate using AIBN as the initiator under heterogeneous conditions

Reverse atom transfer radical polymerization of methyl acrylate in the presence of a conventional radical initiator (2,2′-azoisobutyronitrile, AIBN) in bulk was successfully implemented via a new polymerization procedure. The system first reacts at 65–70°C for ten hours, then polymerizes at 100°C. Various mole ratios of AIBN to CuIICl2 were used in this work, all of which result in a well-controlled radical polymerization with high initiation efficiency and narrow molecular weight distribution, i.e., the polydispersity is as low as Mw/Mn = 1.36.

Crystalline transition in Nylon 10 10

Variable-temperature X-ray diffraction is used to monitor the crystalfine transition of Nylon 10 10. It could be found that the α-phase of the sample transforms into a γ-phase at about 135°C, if the sample is heated from room temperature to a high temperature which is the sit-called Brill transition of Nylon 10 10, In addition. Nylon 10 10 was found to crystallize directly in t kind of o-phase from the melt at high temperature which is much different from the behavior of Nylon 66 and Nylon 10 12, Upon further cooling to room tempera ture, Nylon 10 10 preserved the α-phase revealing two peaks in its XRD patterns. However, if the Nylon 10 10 mple with γ-form was not melted, but immediately cooled from a temperature between T B and T m , the reverse transition from γ-form to α-form could be observed at about 130°C, indicating reversible Brill transition of Nylon 10 10.

Synthesis of a Star‐Shaped Copolymer with a Hyperbranched Poly(3‐methyl‐3‐oxetanemethanol) Core and Tetrahydrofuran Arms by One‐Pot Copolymerization

A star-shaped copolymer consisting of a hyperbrached poly(3-methyl-3-oxetanemethanol) core and polytetrahydrofuran arms was obtained by a one-step cationic copolymierization of 3-methyl-3-oxetanemethanol with tetrahydrofuran initiated by BF 3 .OEt 2 . Tetrahydrofuran served as a solvent at the earliet stage of the polymerization. After 3-methyl-3-oxetanemethanol exhausted essentially, the resulting hyperoranched species acted as a macro-initiator, and initiated the cationic polymerization of tetrahydrofuran. This can be attributed to the large difference in reactivities of the monomers.

Reverse atom-transfer radical polymerization at room temperature

This paper aims at reporting on the “living”/controlled radical polymerization of methyl methacrylate initiated with the benzoyl peroxide (BPO)/CuIX (X=Br,Cl)/2,2-bipyridine (bpy) redox system at room temperature. No control is observed for the polymerization conducted in bulk and in toluene, whereas a polymer with predetermined molecular weight and rather narrow molecular weight distribution is formed in butanone. The solvent has thus a decisive effect on the reverse atom-transfer radical polymerization of methyl methacrylate initiated with the BPO/CuIX (Xu2009= Br,Cl)/bpy ternary system at 25°C.