Variable temperature X ray diffraction(XRD) was used to investigate the crystalline transition of Nylon 1012. The results show that Nylon 1012 undergoes a crystalline relaxation between the glass transition temperature and the melting point. We thus demonstrate, for the first time, the presence of the Brill transition in Nylon 1012, a phenomena that has been extensively studied in Nylon 66. It is found that the Brill transition temperature is about 120 ℃ and we have also showed that the Brill transition of Nylon 1012 is reversible when cooling the high temperature pseudohexagonal structure to room temperature. [WT5HZ]
The new approach for synthesis of hyperbranched polymers from commercially available A2 and BB'2 type monomers was extended to synthesize hyperbranched copolymers. In this work, hyperbranched copoly(sulfone-amine) was prepared by copolymerization of divinyl sulfone (A2) with 4,4'-trimethylenedipiperidine (B2) and N-ethylethylenediamine (BB'2). During the reaction,secondary-amino groups of B2 and BB'2 monomers react rapidly with vinyl groups of A2 monomers within 35 s, generating a type of intermediate containing one vinyl group and two reactive hydrogen atoms. Now the intermediates can be regarded as a new BB2 type monomer, whichfurther polymerizes to form hyperbranched copoly(sulfone-amine). The polymerization mechanism was investigated with FTIR and LC-MSD. The degree of branching (DB) of hyperbranched copolymers increased with decreasing the ratio of 4, 4'-trimethylenedipiperidine to N-ethylethylenediamine, so DB can be controlled. When the initial mole ratio of B2 to BB2 was equal to or higher than four, r≥4, resulted copolymers were semi-crystalline, while copolymers with r<3 were amorphous.
The preparation and characterization of the crystalline inclusion complexes between a polymeric guest, poly(1,3-dioxolane) (PDXL), and small-molecular hosts, cyclodextrins (CDs) are reported. It is observed that the polymer guest can form crystalline inclusion complexes with three kinds of cyclodextrins, which may be attributed to the high oxygen atom density in PDXL chain. The crystalline inclusion complexes were characterized with FTIR, TGA, X-ray diffraction, SEM, 1H NMR and 13C CP/MAS NMR spectroscopes. It was found that the crystalline inclusion complexes have higher temperature stability than the pure CDs. The X-ray powder diffraction patterns of the crystalline inclusion complexes proved that they have columnar structures. 13C CP/MAS NMR spectra of the crystalline inclusion complexes indicate that CDs adopt a more symmetrical conformation in the complexes, while pure CDs assume a less symmetrical conformation in the crystal without a guest inside their cavities. The morphology of the crystal was observed by means of SEM.
Hyperbranched poly(3-ethyl-3-oxetanemetha-nol)-graft-poly(2-dimethylaminoethyl methacrylate) (HP-g-DMA) with a three-demensional structure was synthesized via oxyanionic polymerization. The hydroxyl groups of hyper-branched poly(3-ethyi-3-oxetanemethanol) (HP) reacted with KH and conversed into potassium alcoholate macroinitiators with high initiating efficiencies. High monomer conversion (>95%) was obtained and no residual macroinitiators or monomer was observed. UV-visible spectra indicate that the aqueous solution of the HP-g-DMA exhibited the lowermost critical solution temperature (LCST). The LCST was influ-enced by the chain length of DMA and pH condition of solu-tion. It is found that LCST decreased with increasing DMA chain length or increasing pH value of solution.
Water\|soluble hyperbranched copoly(ester\|amine)s with various degree of branching (DB) were prepared \%via\% the "A\-2+B\-2+BB′\-2" approach. Due to the faster reaction between A and B functional groups, the intermediate containing one A group and two B′ groups was generated\% in situ\%. Further self\|polyaddition of the AB′\-2 intermediate gave hyperbranched polymer. In this communication, A\-2 is ethylene diacrylate (EDA), B\-2 is piperazine (PZ), and BB′\-2 is 1\|(2\|aminoethyl)piperazine (AP). The combination of mass spectrum and \%in situ\% FTIR determined the reaction mechanism and propagating paths predicted. DB of the resulting branched poly(ester\|amine)s decreases with increasing the feed ratio of PZ to AP. In the same molecular weight, the inherent viscosity of the polymers presented here increases with decreasing DB. The simplicity of the reaction process, the controllability of the architecture, and the commercially availability of the raw materials would make this approach attractive in the large scale manufacture and application of hyperbranched polymer materials.
