Pairs Of Amino Terminated Polyethylene Glycol Preparation And Nylon 1212 / Polyethylene Glycol Block Copolymer Synthesis

Amine-terminated poly(ethylene glycol)(PEG-NH₂) was synthesized using Gabriel method, in which the end hydroxyl groups were converted to amino groups. During the synthesis, poly (ethylene glycol) tosylate (PEG-OTs) was prepared using triethylamine as a catalyst at first, and then PEG-OTs was reacted with potassium salt of phthalimide (PPI) as nucleophile to produce the poly (ethylene glycol) phthalimide derivative (PEG-PI) . The PEG-PI reacted with carboxamide hydrazine to give the primary amine(PEG-NH₂). Triethylamine replaces the pyridine as the catalyst which can avoid the breakdown of PEG's backbone in the pyridine long-term reaction. A series of solvents with different SICs were investigated. Among them, DMF was the best . The PEG-NH₂ was characterized using IR, ¹HNMR and element analyses. The result of element analysis proved that the hydroxyl conversions were 86.6%, 92.4%, 94.4%, respectively, for three samples from PEG-6k, PEG-4k, PEG-2k.PA1212 was synthesised using DC12 as a molecular weight regulator. PA1212-b-PEG block copolyetheramides with different block lengths of the hard and soft segments were synthesized through melt polymerization. The result of end-group analysis using base-acid titration indicates that the end groups of PA1212 and PA1212-b-PEG were -COOH. The polymerization process can be even carried out without catalyst. In comparison to the melt polymerization of the hydroxy polyether and PA1212, the vacuum level could be reduced to atmosphere pressure. The melting point and inherent viscosity of PA1212-b-PEG indicate that the PEG-NH₂ makes the melting point of block copolymer lower than that of PA1212. Furthermore, it was shown that the solvent-resistant of the block copolymers was quite similar to that of PA1212.The melting and crystallization behaviors of PA1212-b-PEG were investigated using Differential Scanning Calorimetry (DSC) and Thermogravitric analysis (TGA). The copolymerization makes PA1212 in copolymer were lower than PA1212 oligmer. The more content of PA1212 segments in copolymer is, the higher the crystallization capacity of the PA1212 is. The melting curve shows the existence of two types of crystals in the PA1212-b-PEG. As the increase of soft segment content, the T_p, T_i and T_f of the copolymer become lower. The thermal stability of PA1212-b-PEG was investigated under N₂ environment. The TG result shows that the decomposion process of PEG-NH₂ is only one step whereas that of PA1212 can be divided into two steps. PA1212-b-PEG exhibits higher docomposion temperature than PEG-NH2 and lower than PA1212. The docomposion of PA1212-b-PEG can also be divided into two steps.The nonisothermal crystallization kinetics of PA1212-b-PEG was investigated. The Avrami index of PA1212-b-PEG is about 4, which implies the complexity of crystal growth. For both B24 and B54 samples, the activation energies of PA1212-b-PEG during crystallization are 94.79 and 96.40 kJ/mol, respectively.