Papers by Keyword: Thermosensitive

Abstract: Thermosensitive conducting composite particles were synthesized using the unsulfonated P(St-NIPAm) as a thermosensitive substrate. A series of characterizations have been performed to study the effects of thermosensitive PANI@poly (St-NIPAm) conductivity performance. Aniline diffused into P(St-NIPAm) particles in solution, and then polyaniline (PANI) was in-situ produced in P(St-NIPAm) particles through oxidation polymerization. The samples showed different particle sizes at different temperatures. The content of conducting polyaniline is dependent on NIPAm feed ratios. The particle electrical conductivity was improved with the increasing NIPAM feed ratios and exhibited thermal responsive electrical conductivity. The thermosensitive conducting composite particles will have wide applications in sensors, for example, they could be used to fabricate smart conductive gel responsive to temperature and moisture.

Abstract: Chitosan, β-glycerophosphate, and glycerol are all biocompatible materials for biomedical application. This work successfully developed a thermosensitive hydrogel composed of CS, β-GP and glycerol. The CS/β-GP/glycerol hydrogel can be made as a transparent solution at room temperature and becomes an opaque and turbid hydrogel after heating. The transmission of visible light at different temperature can be measured by a visible micro spectrophotometer combined with a precise temperature control of the demountable liquid cell. A tunable transmission of visible light hydrogel was developed. Moreover, the composition of such hydrogel is safely used and it is potential for biomedical applications.

Abstract: Objectives, which is motional on the batter field, such as vehicles, tanks, planes, warships, firing cannons, etc. They are all active objects. On the surface of these objects there have very higher temperatures than around background, they have special pictures, and are easy found by thermal infrared reconnaissance systems. In this study, itaconic acid (IA) was co-polymerized with N, N-diethylacrylamide (DEA) monomer to improve the swelling behavior and the total absorbing water. These copolymer materials were prepared by changing the initial DEA/IA molar ratio and total monomer concentration. The chemical structure of materials was characterized by fourier transform infrared (FTIR) spectroscopy. In comparison with the PDEA hydrogel, the equilibrium swelling ratio (ESR) of the materials increase with the increase of IA content in the feed and the swelling dynamics behaviors of the different composition ratios of the P(DEA-co-IA) materials on the different temperatures was investigated in detail. Using the big hot-inertia of water, the superabsorbent material of the object surface is propitious to debase the object temperature, which suggests that these materials have potential application as thermal infrared camouflage materials.

Abstract: A series of poly (N-isopropylacrylamide-co-glycyrrhetinic acid) (P(NIPAAm-co-GA)) microgels were prepared by dispersion copolymerization. The morphologies of the microgels were observed by field scanning electron microscopy (FE-SEM) and transmission electron microscope (TEM). The temperature sensitivity of microgels was examined by measuring the optical transmittance of the microgel aqueous solution. Cytotoxicity of the microgels was investigated by MTT assay. The results indicated that microgel particles had a regular spherical shape of about 500 nm with narrow size distributions. Moreover, P(NIPAAm-co-GA) microgels exhibited good temperature sensitivity and low toxicity. This novel microgel could be expected as good candidate for controlled growth factor release.Intorduction

Abstract: A thermoresponsive glycopolymer poly-(N-isopropylacrylamide-co-6-O-vinylsebacoyl D-glucose) (poly-NIPAM-co-VSEG; PNE) has been prepared by free radical polymerization process, and subsequently processed into nanofibers with poly-L-lactide-co-ε-caprolactone (PLCL) using electrospinning. The thermoresponsive glycopolymer materials have been characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H NMR, and scanning electron microscopy (SEM). And the lower critical solution temperature (LCST) of these thermoresponsive materials was also measured. The nanofibers containing PNE can greatly selective recognize with lectin Concanavalin A (Con A), and the adsorbed Con A can be easily eluted by 1 M glucose solution. These results indicate that PNE can separate and purify proteins, and also the temperature sensitive characteristic has the potential to achieve the intelligent control.

Abstract: This article mainly introduces the manufacture and application principle of photosensitive color-changing fiber and thermosensitive color-changing fiber in clothing color-changing materials so as to let people better understand them.

Abstract: A fast responsive thermosensitive hydrogel poly((N-isopropy- lacrylamide/Sodium acrylate) (P(NIPAm/AA-Na)) were prepared by free radical polymerization methods. The low critical soluble temperatures (LCST) of the hydrgols is about 60°C in 5%wt aqueous solutions. The heterogeneous macroporous structure was observed by SEM. Deswelling degree of the hydrogel is up to 75% in 60 seconds. The 1A rating wood stacking fire were suppressed with water, colloid extinguishing agent B of Zhejiang University and the thermosensitive P(NIPAm/AA-Na) hydrogel respectively. Radiant heat and the temperature were recorded by several heat probes and thermocouples during extinguishing. The results showed that the fire extinguishing-time of the thermosensitive hydrogel is shortest at the same practical rate of application among the three. Consumption of extinguishing agent is the least. The water damage to the section unfired is low after fire extinguishing. The extinguishing agent residual is easy to clean, so the extinguishing efficiency is high.

Abstract: Marine mussels secrete remarkable mussel adhesive proteins (MAPs) for adherence to the substrates upon which they reside. Inspired by the intermolecular cross-linking characteristics of MAPs, we report the synthesis of thermosensitive dopamine modified Pluronic copolymer (PluF127-Dopa) with high coupling efficiency. Under certain temperature and concentration, PluF127-Dopa copolymers in aqueous solution self-assemble into micelles and are able to rapidly form a more stable hydrogels upon addition of oxidizing reagents such as NaIO4, resulting from oxidative cross-linking of dopamine. UV-vis spectroscopy was utilized to identify the reaction intermediates. The sol-gel transition curves of cross-linked PluF127-Dopa hydrogels (CL-PluF127-Dopa) were determined by a vial inversion method. The critical gelation concentration of CL-PluF127-Dopa hydrogels was significantly lower than those for PluF127-Dopa and unmodified Pluronic F127. The apparent mechanical strength of CL-PluF127-Dopa hydrogels was dramatically enhanced compared to those unmodified Pluronic copolymer hydrogels, suitable for sustained drug delivery. These new biomimetic materials are expected to have potential uses in biomedical applications.

Abstract: Poly(N,N-diethylacrylamide) (PDEA) hydrogel is known for their intelligent reversible swelling/deswelling behavior in response to temperature changes across a lower critical solution temperature (LCST) at around 31oC. In this study, itaconic acid (IA) was co-polymerized with N, N-diethylacrylamide (DEA) monomer to improve the swelling behavior and the total absorbing water. These copolymer hydrogels were prepared by changing the initial DEA/IA molar ratio and total monomer concentration. The chemical structure of hydrogels was characterized by fourier transform infrared (FTIR) spectroscopy. In comparison with the PDEA hydrogel, the equilibrium swelling ratio (ESR) of the hydrogels increase with the increase of IA content in the feed and the swelling dynamics behaviors of the different composition ratios of the P(DEA-co-IA) hydrogels on the different temperatures was investigated in detail.

Abstract: Poly(N,N-diethylacrylamide) (PDEA) hydrogels possess a lower critical solution temperature (LCST) at around 31oC. When the external temperature is raised above the LCST, the hydrogels experience abrupt and drastic shrinkage. This unique property makes them very useful for biomedical applications such as on-off switches for modulated drug delivery and tissue engineering. In this study, itaconic acid (IA) was co-polymerized with N, N-diethylacrylamide (DEA) monomer to improve the LCST to the physiologic temperature about 37oC. These copolymer hydrogels were prepared by changing the initial DEA/IA molar ratio and total monomer concentration. The interior morphologies of hydrogels were characterized by scanning electron microscopy (SEM). In comparison with the PDEA hydrogel, the equilibrium swelling ratio (ESR) and LCST of the hydrogels increase with the increase of IA content in the feed. The deswelling dynamics behaviors of the different composition ratios of the P(DEA-co-IA) hydrogels on the different temperatures was investigated in detail.