Mingwei Zhao,Mingwei Gao,Caili Dai,Mingyong Du,Yifei Liu,Chenwei Zou,Jiaping Tao,Xinke Wang,Tao Wang
In this work, we report a simple class of photo-responsive system that consists of cationic surfactant , N -methyl- N -cetylpyrrolidinium bromide (C 16 MPB), and the photoresponsive organic derivative, trans - ortho -methoxycinnamic acid ( trans -OMCA). The system is studied by UV spectra, cryo -transmission electron microscopy, and rheological measurements. C 16 MPB and trans -OMCA in basic aqueous solution can self-assemble to form viscoelastic wormlike micelles . Upon exposure to UV light , OMCA undergoes a photoisomerization from trans to cis , which results in a change of the geometry of the C 16 MPB–OMCA complexes. The wormlike micelles can transform into spherical or rodlike micelles. We hope this study may enrich the understanding of photo-responsive wormlike micelles composed by cationic surfactants and photo-sensitive additives in water.
Yan Li,Zhen Yao,Zhen-hua Chen,Shao-long Qiu,Changchun Zeng,Kun Cao
In this paper we report a facile process to introduce ionic interactions to polypropylene (PP) based on Zn-neutralization and amine modification reactions of maleic anhydride grafted PP (PP-g-MAH) for the preparation of high melt strength PP (HMSPP). A series of PP ionomers with different structures and ionic properties were synthesized via the choice of the pendant groups, and their effects on the rheological properties were investigated. Increased melt viscosity and elasticity resulting from the ionic interaction and aggregation of the ionic domains were confirmed by both shear and extensional rheological measurements. The rheological behaviors of the PP ionomers share features similar to those of critical gels. Moreover, foaming behaviors of the PP ionomers were investigated by using CO 2 as the foaming agent and compared to that of the original PP-g-MAH. All ionomers show significantly improved foamability. Of the group of PP ionomers, the amine-modified PP ionomers (Zn-AM-ionomer) shows the best foamability due to the combined effects of optimal rheological properties and the underlying favorable interactions with CO 2 . These findings provide new insights into the design of high melt strength polypropylenes for foaming application assisted with CO 2 .
Collagen/cellulose blended solutions with collagen/cellulose mass ratio (Col/Cel) of 0, 1/40, 1/20, 1/10 and 1/5 were prepared using [Emim]Ac as solvent. The interactions between the two polymers before and after regeneration were investigated. In steady shear flow, all of the experimental viscosity values were greater than those of the estimated values calculated from the log-additivity rule for each sample, suggesting interactions between the two polymers in solutions. All solutions exhibited shear thinning behavior and the flow curves could be described by Cross model. Zero shear viscosity ( η
0 ) versus Col/Cel was examined and a linear increase (from 8.73 to 16.39 Pa·s) can be observed for η
0 as Col/Cel ≤ 1/10, while there was only a slight increase (from 16.39 to 18.42 Pa·s) in η
0 as Col/Cel increased to 1/5. Dynamic rheology results suggested the existence of aggregates in solution with Col/Cel = 1/10. Furthermore, the activation energy of solution was 84.5 kJ mol −1 as Col/Cel = 1/10, higher than that of cellulose solution (44.2 kJ mol −1 ). Regenerated films were prepared and characterized to trace back the interactions between the two polymers in [Emim]Ac. Fourier transform infrared spectroscopy indicated the hydrogen-bond interaction between collagen and cellulose in films. The denaturation temperature of collagen in films with Col/Cel ≤ 1/10 could be improved, but it was decreased with the increase of collagen content, and finally was reduced to be close to that of collagen as Col/Cel = 1/5. The features of dynamic mechanical analysis for films were indicative of the lack of homogeneity between collagen and cellulose as Col/Cel = 1/5. Atomic force microscopy images further confirmed the phase-separation when Col/Cel = 1/5.
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