JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2014
·Vol. 52
·期 17
·2442-2453
·
IF 3.245
Bingyan Jiang,Lei Zhang,Jie Yan,Qingquan Huang,Bing Liao,Hao Pang
A series of well-defined thermoresponsive graft polymers with different lengths and graft densities, poly(glycidyl methacrylate)- graft -poly( N -isopropylacrylate) (PGMA- g -PNIPAM), were successfully prepared by combination of controlled/living free radical polymerization and click chemistry. Effects of grafting length and density on the thermoresponsive behavior, aggregating mean diameter, and self-assembly morphology are systematically investigated. The thermosensitive characteristics of graft polymers in aqueous solution prove that the length and graft density had positive co-relationship with the lower critical solution temperature value and mean diameter of micelles as well as the size distribution, while the effect of graft length of polymers is more significant than that of density. Transmission electron microscopy analysis shows that the conformations of PGMA 45 - g -PNIPAM 20 and PGMA 45 - g -PNIPAM 46 with longer length and bigger grafting density in aqueous solutions are spherical nanoparticles with the increasing trend of the diameters, while that of PGMA 45 - g -PNIPAM (73, 50%) shows a spherical-like morphology, which indicates that the graft length and density have a significant effect on the mean diameter of micelle but not on the self-assembly morphology. These results reveal that to obtain desired thermoresponsive behavior and self-assembly morphology of functional polymers, it is essential to design and fabricate the structure of graft polymers with proper length and graft density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52 , 2442–2453
研究领域:
高分子化学
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材料科学
·
纳米医学
·
药物递送
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生物材料
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智能响应材料
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2013
·
IF 2.112
Xiumei Tai,Jing hong Ma,Zhiping Du,Wanxu Wang
The temperature sensitive SiO 2 /PNIPAAm composite microspheres were designed and successfully synthesized. The influences of monomer concentration, reaction time, reaction temperature and initiator amount on water contact angel of the prepared microspheres were investigated. The structure, morphology, and surface composition were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS). The temperature sensitive properties in aqueous solution were studied by water contact angle measurement instrument and dynamic light scatter (DLS). The results show that the low critical solution temperature (LCST) of SiO 2 /PNIPAAm composites is around 304 K and the particle is monodisperse microsphere .
研究领域:
高分子材料学
·
纳米医学
·
药物递送系统
·
生物材料
·
温敏材料
·
胶体与界面化学
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER RESEARCH
·
2012
·Vol. 19
·期 11
·1-7
·
IF 1.733
Yu Wei-Na,Liu Shou-Xin,Wang Hong-Mei,Tian Rong
Temperature-responsive P(NIPAM- co -HMAM)- b -PEO- b -P(NIPAM- co -HMAM) triblock copolymers were synthesized by an atomic transfer radical polymerization (ATRP) method without freeze–pump–thaw cycles. The composition, structure, and molecular weight of the synthesized block copolymer were characterized by 1 H NMR and GPC. The phase transitions induced by temperature for different copolymers in dilute aqueous solutions have been studied using transmittance measurements, laser particle size measurements, viscosity analysis, and surface tension measurement, which showed that the HMAM content and the PEO (or PEG) chain length in the synthesized triblock copolymer affects the copolymer’s lower critical solution temperature (LCST). The micellization behavior of each temperature-responsive triblock copolymer was investigated by fluorescence probe measurements and transmission electron microscopy (TEM), which showed that the triblock copolymers form stable micelles above the LCST. The introduction of the HMAM component and the formation of micelles represent the first steps in the development of an injectable gel that forms in situ through chemical and physical crosslinking.
研究领域:
高分子化学
·
生物材料
·
药物递送系统
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2013
·Vol. 5
·期 3
·761-770
·
IF 5.231
Wenlong Li,Peiyi Wu
The influence of different Ionic Liquids (ILs) on the phase transition behavior of poly(N-vinylcaprolactam) (PVCL) solution is investigated by differential scanning calorimetry (DSC) and turbidity measurements, in combination with FT-IR spectroscopy. The DSC and turbidity results reveal that hydrophilic ILs at a concentration of 0.25 mol L−1 only slightly change the transition temperature. The LCST experiences an increase while the phase separation behavior disappears gradually as the concentration of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) increases from 0 to 1.0 mol L−1. In contrast, the addition of hydrophobic ILs, especially 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([EMIM][NTf2]), even at a low concentration, greatly raises the LCST, indicating the possibility of hydrogen bonding between [EMIM][NTf2] and PVCL. Finally, temperature-dependent FTIR spectra are employed to elucidate the dynamic mechanism of the different influences on the phase transition of PVCL. The hydrophilic ILs can change the state of the PVCL chains indirectly by varying their interaction with water molecules. For comparison, the formation of hydrogen bonds between the unsaturated C–H of [EMIM][NTf2] and the CO of PVCL results in a higher temperature and more energy to complete the phase transition. However, with the continual increasing of the concentration, extra [EMIM][NTf2] can not be well dispersed in water due to its hydrophobicity, so the LCST undergoes a decrease and finally reaches an equilibrium. Additionally, hydrophilic ILs tend to distribute in the solution, while hydrophobic ILs, especially [EMIM][NTf2], are prone to be wrapped in polymer chains of the aggregates after phase separation. Furthermore, both types of IL experience the process of hydrogen bond disruption and chain aggregation.
研究领域:
高分子化学
·
物理化学
·
热力学
·
药物递送系统
·
刺激响应材料
✓ 已验证
DOI
高影响因子
Soft Matter
·
2014
·Vol. 10
·期 20
·3578-3586
·
IF 4.151
Lei Hou,Peiyi Wu
The self-aggregation behavior of poly(N-isopropylacrylamide)-b-poly(N-vinylcaprolactam) (PNIPAM-b-PVCL) during the thermal-induced phase transition in water was explored by a combination of calorimetric, turbidity, dynamic light scattering (DLS) and FTIR measurements. Only one transition can be observed via all detecting methods, revealing the cooperative aggregation of the two distinct temperature-sensitive segments. What is more, the combination of strong hydrophobic interactions among the entire polymer chains and hydrogen bonds of CO…H–N within PNIPAM segments results in the sharp variations at the LCST and gradual variations above the LCST during the phase transition of PNIPAM-b-PVCL aqueous solution upon heating. Additional analysis by perturbation correlation moving window (PCMW) and two-dimensional correlation spectroscopy (2Dcos) indicates that the hydrophobic C–H groups have an earlier response than the relatively hydrophilic CO groups during the LCST transition.
研究领域:
高分子化学
·
软物质物理
·
生物材料
·
药物递送
·
纳米医学
·
分子自组装
·
光谱分析
✓ 已验证
DOI
高影响因子
POLYMER
·
2015
·
IF 3.562
Xue Jiang,Chun Feng,Guolin Lu,Xiaoyu Huang
A homopolymer strategy was developed to synthesize temperature and pH/CO 2 stimulus-responsive homopolymers. A new class of acrylamide monomers bearing oligo(ethylene glycol) unit and N,N -diethylaminoethyl group were designed and prepared through Aza-Michael addition reaction followed by amidation with acryloyl chloride using amino group as a linkage to connect oligo(ethylene glycol), N,N -diethylaminoethyl, and polymerizable double bond groups together. Subsequently, the corresponding homopolymers containing oligo(ethylene glycol) unit and N,N -diethylaminoethyl group in each repeated unit were prepared via RAFT polymerization with controlled molecular weights and relatively narrow molecular weight distributions . The lower critical solution temperature (LCST) of homopolymer was examined to be influenced by molecular weight, salt concentration, and pH value of aqueous solution. The LCSTs of homopolymers could be tuned in a wide temperature window by changing pH value of aqueous solution and it increased with the decrease of pH value. Particularly, CO 2 gas as a unique pH stimulus can also reversibly adjust the solubility of homopolymer without the addition of acids or bases.
研究领域:
高分子化学
·
智能材料
·
药物递送
·
生物医用材料
·
刺激响应材料
✓ 已验证
DOI
高影响因子
IRANIAN POLYMER JOURNAL
·
2023
·Vol. 32
·期 9
·1189-1197
·
IF 3.1
Luo Yanrong,Lu Chunlan,Zhang Xiaolin,Zhan Shiping
With the widespread use of hydrogels, injectable hydrogels for the human body require higher safety and non-toxicity. The most important is the choice of cross-linking agent to be green. In this study, acylated chitosan macromolecular crosslinkers (MCS) were prepared by maleic acid (MA) and chitosan (CS). Its structure was confirmed by FTIR and 1 H NMR and its degree of acylation was also determined. Then, a series of polymeric network hydrogels were investigated. The cross-linked copolymer poly( N -isopropyacrylamide-maleic acid copolymer)/acylated chitosan P(NIPAM- co -MA)/MCS is a series of thermosensitive hydrogels formed by free radical polymerization of NIPAM and MA with MCS as cross-linking agent. The apparent morphology, thermosensitive transition point, and hydrophilicity were investigated. The results show that the hydrogel has a homogeneous pore structure inside. The optimal low critical solution temperature (LCST) was 36.66 ℃. In addition, with the increase of maleic acid content, the water contact angle of the hydrogel is smaller, that is, the hydrophilic effect is better. The results indicate that the P(NIPAM- co -MA)/MCS hydrogels were synthesized successfully and may be a potential material for biomedical, drug delivery, or absorption application. This study can provide a certain research basis and relevant theoretical basis for clinical practice. Graphical abstract
研究领域:
高分子科学
·
材料科学
·
生物医学工程
·
药物制剂技术
✓ 已验证
DOI
高影响因子
Journal of Macromolecular Science Part B-Physics
·
2023
·
IF 1.4
Xinyun Liu,Hua Lei,Jing Xiong
Intelligent or smart polymer materials are those which are either “active” or responsive to a variety of environmental stimuli, such as changes in pH, temperature, ionic strength or electric field, or the presence of a specific chemical substrate. A thermally sensitive polymer, poly(N-isopropylacrylamide) (PNIPAAm), has been of great interest because aqueous solutions of PNIPAAm undergo fast, reversible switching of hydrophilicity/hydrophobicity around 32 °C at their lower critical solution temperature (LCST) of about 29–38 °C (different with variations in their structure). PNIPAAm chains show an expanded conformation in water below the LCST because of strong hydration and change to the compact forms above the LCST by sudden dehydration; this is the reversible switching effect of hydrophilic to hydrophobic. These switchable materials may have wide applications in functional textiles, controllable drug release and special fibers. Electrospinning is a simple, convenient, and versatile technique for generating fibers with diameters that range from several micrometers to tens of nanometers. Herein, we report an electrospinning method to prepare nano PNIPAAm fiber and their thermal response was characterized. Based on the results, the diameters of the PNIPAAm nanofibers within the respective system were around 200 nm and beads-less; they were successfully prepared by an electrospinning method in all cases and the reversible switching with LCST (32 °C) feature was observed clearly in the fibers.
研究领域:
材料科学
·
高分子科学
·
纳米技术
·
智能材料
·
静电纺丝技术
✓ 已验证
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2013
·Vol. 52
·期 1
·87-95
·
IF 3.543
Aihua Li,Jingquan Liu,Guozhen Liu,Jizhen Zhang,Shengyu Feng
In this article, the preparation of fluorescent nanohybrids with core–shell structure and metal-enhanced fluorescence (MEF) effect was presented. The fluorescent core–shell nanohybrids were prepared using silver nanoparticles (AgNPs) as cores and fluorophore tethered thermoresponsive copolymers with tunable lower critical solution temperature (LCST) from 15 to 90 °C as shells. These thermoresponsive copolymers were synthesized by the random copolymerization of oligo(ethylene oxide) acrylate and di(ethylene oxide) ethyl ether acrylate using reversible addition–fragmentation chain transfer polymerization and grafted on to AgNPs surface via Ag–S coordination interaction. By thermal manipulation of polymer spacer between AgNPs and fluorophores, the tunable MEF was achieved. It was also revealed that the fluorescent nanohybrids would exhibit maximal MEF when the polymerization degree was tuned to 350. The manipulation of the solution temperatures below and above LCST resulted in switchable MEF behavior. In addition, the phase transition process of the thermoresponsive copolymer was also studied by MEF effect using this fluorescent core–shell nanohybrid design. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52 , 87–95
研究领域:
材料科学
·
纳米技术
·
高分子化学
·
物理化学
·
光学
·
表面科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）