由聚丙二醇二缩水甘油醚和甘油通过质子转移聚合(proton transfer polymerization)一步法制备了端羟基的温敏性超支化聚醚.聚合产物的分子量(Mn)在1.76×104~2.43×104之间,玻璃化转变温度(Tg)在-31.5~-26.7℃之间,热分解温度(Td)在367~376℃之间.通过控制聚丙二醇二缩水甘油醚和甘油的投料比,实现了对温敏性超支化聚醚最低临界溶解温度(LCST)的调节,LCST可控制在28.3~39.6℃之间. 相似文献
A new programed upper critical solution temperature-type thermoresponsive polymer was developed using water-soluble anionic polymer conjugates derived from polyallylamine and phthalic acid with cleavage-induced phase transition property. Intrinsic charge inversion from anion to cation of the polymer side chain is induced through a side chain cleavage reaction in acidic aqueous media. With the progress of side chain cleavage under fixed external conditions, the polymer conjugates express a thermoresponsive property, followed by shifting a phase boundary due to the change in polymer composition. When the phase transition boundary eventually reached the examined temperature, phase transition occurs under fixed external conditions. Such new insight obtained in this study opens up the new concept of time-programed stimuli-responsive polymer possessing a cleavage-induced phase transition. 相似文献
A versatile method to prepare non‐covalently crosslinked polyHIPEs hydrogels from oil‐in‐water high internal phase emulsions (HIPEs) whose aqueous phase contained thermo‐responsive linear polymers is described. The interconnected pore structure of the polyHIPEs is maintained by reversible physical aggregation of thermo‐responsive polymer chains in an aqueous environment. This method to prepare interconnected porous hydrogels using a thermal trigger in the guise of thermo‐responsive polymers by emulsion templating requires no chemical reaction during solidification of the template. This particular feature could provide a safer route to injectable scaffolds as issues of polymerisation/crosslinking chemistry and residual initiator fragments or monomers do not arise 相似文献
The monomers 2‐methyl‐2‐oxazine (MeOZI), 2‐ethyl‐2‐oxazine (EtOZI), and 2‐n‐propyl‐2‐oxazine (nPropOZI) were synthesized and polymerized via the living cationic ring‐opening polymerization (CROP) under microwave‐assisted conditions. pEtOZI and pnPropOZI were found to be thermoresponsive, exhibiting LCST behavior in water and their cloud point temperatures (TCP) are lower than for poly(2‐oxazoline)s with similar side chains. However, comparison of poly(2‐oxazine) and poly(2‐oxazoline)s isomers reveals that poly(2‐oxazine)s are more water soluble, indicating that the side chain has a stronger impact on polymer solubility than the main chain. In conclusion, variations of both the side chains and the main chains of the poly(cyclic imino ether)s resulted in a series of distinct homopolymers with tunable TCP. 相似文献
The phase behavior and rheology of a range of physical mixtures of self-assembling octapeptide FEFEFKFK and its conjugate with the thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAAM) have been studied. These systems typically combined the thermo-responsive character of PNIPAAM and the gelling property of octapeptides where both the elastic behavior and macroscopic melting of the system could be controlled by varying the ratio of pure peptide to peptide-polymer conjugate. 相似文献
The combination of magnetic nanoparticles with thermoresponsive polymer systems leads to the formation of hybrid particle
dispersions or composites with a variety of interesting properties and perspectives, including instant dispensability, thermoreversible
formation of magnetic fluids, and novel magnetoresponsive properties. Special interest is gained by the magnetic heatability
of magnetic particles that allows the activation of thermal effects by the application of a high-frequency electromagnetic
field. This review summarizes the recent developments in this young field of research with application potential for magnetic
separation, drug release systems, and for sensor and actuator purposes. 相似文献
Summary: Solutions of poly(N‐isopropylacrylamide) (PNIPA) with added sodium dodecyl sulfate (SDS) were investigated by light scattering methods at temperatures of 15–40 °C. The formation of well‐defined nanoparticles of PNIPA was observed on heating at low SDS additions. The effects of PNIPA and SDS concentrations and the molecular weight of PNIPA on nanoparticle parameters were investigated. An interpretation based on stabilization of PNIPA nuclei by SDS was suggested.
The proposed mechanism of nanoparticle formation. 相似文献