scholarly journals Phase Diagrams of Smart Copolymers Poly(N-isopropylacrylamide) and Poly(sodium acrylate)

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Iwona Zarzyka ◽  
Maria Laura Di Lorenzo ◽  
Marek Pyda
Keyword(s):  
Water System ◽  
Solution Temperature ◽  
Sodium Acrylate ◽  
Linear Polymers ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Mixing Behavior ◽  
Linear Poly ◽  
Copolymer Poly

The phase behavior of linear poly(N-isopropylacrylamide) (PNIPA), linear copolymer poly(N-isopropylacrylamide) and poly(sodium acrylate) (PNIPA-SA), and chemically cross-linked PNIPA in water has been determined by temperature modulated differential scanning calorimetry (TM-DSC). Experiments related to linear polymers (PNIPA and PNIPA-SA) indicated nontypical demixing/mixing behavior with a lower critical solution temperature (LCST), which do not correspond to the three classical types of limiting critical behavior. Some similarities and differences are observed in comparison to our literature data using standard TM-DSC for PNIPA/water. Furthermore no influence of composition cross-linked PNIPA/water system on demixing/mixing temperature was observed.

scholarly journals Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels

2016 ◽  
Vol 2 (1) ◽  
pp. 1-4
Author(s):  
Sylvia Pfensig ◽  
Daniela Arbeiter ◽  
Klaus-Peter Schmitz ◽  
Niels Grabow ◽  
Thomas Eickner ◽  
...  
Keyword(s):  
Mechanical Characterization ◽  
Heating Temperature ◽  
Controlled Drug Release ◽  
Solution Temperature ◽  
Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Temperature Range ◽  
Hybrid Hydrogels ◽  
Higher Temperature

AbstractIn this study, varying amounts of NIPAAm and an ionic liquid (IL), namely 1-vinyl-3-isopropylimidazolium bromide ([ViPrIm]+[Br]−), have been used to synthesize hybrid hydrogels by radical emulsion polymerization. Amounts of 70/30%, 50/50%, 30/70%, 15/85% and 5/95% (wt/wt) of PIL/pNIPAAm were used to produce hybrid hydrogels as well as the parental hydrogels. The adhesive strength was investigated and evaluated for mechanical characterization. Thermal properties of resulting hydrogels have been investigated using differential scanning calorimetry (DSC) in a default heating temperature range (heating rate 10 K min−1). The presence of poly ionic liquids (PIL) in the polymer matrix leads to a moved LCST (lower critical solution temperature) to a higher temperature range for certain hybrid hydrogels PIL/pNIPAAm. While pNIPAAm exhibits an LCST at 33.9 ± 0.3°C, PIL/pNIPAAm 5/95% and PIL/pNIPAAm 15/85% were found to have LCSTs at 37.6 ± 0.9°C and 52 ± 2°C, respectively. This could be used for controlled drug release that goes along with increasing body temperature in response to an implantation caused infection.

scholarly journals Aggregation of Gold Nanoparticles in Presence of the Thermoresponsive Cationic Diblock Copolymer PNIPAAM48-b-PAMPTMA6

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4066
Author(s):  
David Herrera Robalino ◽  
María del Mar Durán del Amor ◽  
Carmen María Almagro Gómez ◽  
José Ginés Hernández Cifre
Keyword(s):  
Gold Nanoparticles ◽  
High Ionic Strength ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Aggregation Process ◽  
Critical Solution Temperature ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Copolymer Poly ◽  
Positively Charged

The adsorption of the thermoresponsive positively charged copolymer poly(N-isopropylacrylamide)-block-poly(3-acrylamidopropyl)trimethylammonium chloride, PNIPAAM48-b-PAMPTMA6(+), onto negatively charged gold nanoparticles can provide stability to the nanoparticles and make the emerging structure tunable by temperature. In this work, we characterize the nanocomposite formed by gold nanoparticles and copolymer chains and study the influence of the copolymer on the expected aggregation process that undergoes those nanoparticles at high ionic strength. We also determine the lower critical solution temperature (LCST) of the copolymer (around 42 °C) and evaluate the influence of the temperature on the nanocomposite. For those purposes, we use dynamic light scattering, UV-vis spectroscopy and transmission electron microscopy. At the working PNIPAAM48-b-PAMPTMA6(+) concentration, we observe the existence of copolymer structures that trap the gold nanoparticles and avoid the formation of nanoparticles aggregates. Finally, we discuss how these structures can be useful in catalysis and nanoparticles recovery.

scholarly journals Influence of Cross-Linking Degree on Hydrodynamic Behavior and Stimulus-Sensitivity of Derivatives of Branched Polyethyleneimine

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1085
Author(s):  
Alina Amirova ◽  
Tatyana Kirila ◽  
Mikhail Kurlykin ◽  
Andrey Tenkovtsev ◽  
Alexander Filippov
Keyword(s):  
Aqueous Solutions ◽  
Mole Fraction ◽  
Solution Temperature ◽  
Linear Polymers ◽  
Intermolecular Hydrogen Bonds ◽  
Critical Solution Temperature ◽  
Cross Linker ◽  
The Cross ◽  
Derivatives Of ◽  
Constant Characteristics

Cross-linked derivatives of acylated branched polyethyleneimine containing 2-isopropyl-2-oxazoline units were investigated in chloroform and aqueous solutions using methods of molecular hydrodynamics, static and dynamic light scattering, and turbidity. The studied samples differed by the cross-linker content. The solubility of the polyethyleneimines studied worsened with the increasing mole fraction of the cross-linker. Cross-linked polyethyleneimines were characterized by small dimensions in comparison with linear analogs; the increase in the cross-linker content leads to a growth of intramolecular density. At low temperatures, the aqueous solutions of investigated samples were molecularly dispersed, and the large aggregates were formed due to the dehydration of oxazoline units and the formation of intermolecular hydrogen bonds. For the cross-linked polyethyleneimines, the phase separation temperatures were lower than that for linear and star-shaped poly-2-isopropyl-2-oxazolines. The low critical solution temperature of the solutions of studied polymers decreased with the increasing cross-linker mole fraction. The time of establishment of the constant characteristics of the studied solutions after the jump-like change in temperature reaches 3000 s, which is at least two times longer than for linear polymers.

scholarly journals Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

2013 ◽  
Vol 9 ◽  
pp. 2803-2811 ◽  
Author(s):  
Julian Fischer ◽  
Helmut Ritter
Keyword(s):  
Differential Scanning Calorimetry ◽  
Lower Critical Solution Temperature ◽  
Setting Time ◽  
Diglycidyl Ether ◽  
Solution Temperature ◽  
Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Lcst Behavior ◽  
Oscillatory Rheology ◽  
Amine Adducts

2-Amino-N-isopropylacetamide and α-amino-ε-caprolactam were reacted with glycerol diglycidyl ether to give novel oligomeric thermoresponsive epoxide–amine adducts. These oligomers exhibit a lower critical solution temperature (LCST) behavior in water. The solubility properties were influenced with randomly methylated β-cyclodextrin (RAMEB-CD) and the curing properties of the amine–epoxide mixtures were analyzed by oscillatory rheology and differential scanning calorimetry, whereby significant differences in setting time, viscosity, and stiffness were observed.

Novel Polymerization of Myrcene in Aqueous Media via Cyclodextrin-Complexes

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
SooWhan Choi ◽  
Helmut Ritter
Keyword(s):  
Room Temperature ◽  
Aqueous Media ◽  
Gel Permeation Chromatography ◽  
Solution Temperature ◽  
Cyclodextrin Complexes ◽  
Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Gel Permeation ◽  
Redox Initiator ◽  
C Nmr

AbstractFree radical homopolymerization with methylated β-cyclodextrin (CD) complexed myrcene (1a) and co-polymerization of 1a with diethyl fumarate (2a) and styrene (3a) were carried out using redox initiator in aqueous media at room temperature. Control experiments showed that uncomplexed myrcene (1) does not polymerize under similar conditions in water. The polymers obtained were characterized by means of 1H/13C-NMR spectroscopy, differential scanning calorimetry (DSC) and gel-permeation chromatography (GPC). Additionally, Nisopropylacrylamide containing copolymer was synthesized in water using redox initiator and the lower critical solution temperature (LCST) behaviour was studied.

Superabsorbent Nanohydrogels of Poly (N-Isopropyl Acrylamide-Co-Itaconic Acid) Grafted on Starch — Synthesis and Swelling Study

Nano LIFE ◽  
2016 ◽  
Vol 06 (02) ◽  
pp. 1650005 ◽  
Author(s):  
Karim Pourjamal ◽  
Marziyeh Fathi ◽  
Ali Akbar Entezami ◽  
Mohammad Hasanzadeh ◽  
Nasrin Shadjou
Keyword(s):  
Itaconic Acid ◽  
Starch Synthesis ◽  
Ammonium Persulfate ◽  
Solution Temperature ◽  
Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Dsc Studies ◽  
Isopropyl Acrylamide ◽  
Effects Of Ph

Biopolymer-based superabsorbent nanohydrogel consisting of N-isopropylacrylamide and itaconic acid (IA) was grafted on to starch backbone in an aqueous solution in the absence of the cross-linker agents. The copolymerization reaction occurred in the presence of ammonium persulfate (APS) as an initiator. The effect of N-isopropylacrylamide-to-IA ratio and different concentrations of initiator were investigated. The nanohydrogel composition was characterized by Fourier transform infrared spectroscopy (FTIR). The thermal stability was analyzed by Thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) studies were employed for determination of lower critical solution temperature in hydrogels. Dynamic light scattering analysis showed a narrow size distribution around 70–200[Formula: see text]nm for the synthesized nanohydrogels. The effects of pH on swelling behavior of the hydrogel were investigated. The obtained nanohydrogels, due to their pH and thermo dual sensitive properties, have the potential to be used in the drug delivery systems.

Thermodynamic Interactions in Blends of Polydienes

1999 ◽  
Vol 72 (4) ◽  
pp. 580-586 ◽  
Author(s):  
Ramanan Krishnamoorti
Keyword(s):  
Small Angle Neutron Scattering ◽  
Room Temperature ◽  
Single Phase ◽  
Solution Temperature ◽  
Scanning Calorimetry ◽  
Binary Blends ◽  
Critical Solution Temperature ◽  
Dsc Measurements ◽  
Lcst Behavior ◽  
Mixed Microstructure

Abstract Thermodynamic interactions and phase behavior in binary blends of model mixed microstructure polybutadienes with model 1,4-polyisoprene were studied using small angle neutron scattering and differential scanning calorimetry (DSC). The microstructure of the polybutadiene ranged from 8% 1,2 (92% 1,4) to 90% 1,2 (10% 1,4) units, while the polyisoprene contained 93% 1,4 and 7% 3,4 units. The blends of protonated polybutadienes (HPB) with deuterated 1,4 polyisoprene (DPI) exhibited lower critical solution temperature (LCST) behavior when the polybutadiene contained 38 mol % or more of 1,2 units. Below this 1,2 content of the polybutadiene, all HPB/DPI blends were found to be phase separated at all temperatures above 25 °C. The DSC measurements revealed that other than a blend containing 8% 1,2-polybutadiene and (protonated) 1,4 polyisoprene, all other blends were single phase at room temperature. These results are understood in the context of previous work performed by Han and coworkers on deuterated polybutadiene-protonated polyisoprene blends.

scholarly journals Phase Behavior and Heat Capacity of {DPnP + Water} Mixtures at the Temperature Range of 273.15–338.15 K

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Mariola Tkaczyk ◽  
Henryk Piekarski ◽  
Paweł Góralski
Keyword(s):  
Heat Capacity ◽  
Critical Concentration ◽  
Homogeneous Solution ◽  
Solution Temperature ◽  
Miscibility Gap ◽  
Differential Heat ◽  
Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Dipropylene Glycol ◽  
Capacity Data

The differential scanning calorimetry method (DSC) was used to examine the miscibility in the{dipropylene glycol propyl ether (DPnP) + water}system. Based on recorded curves of differential heat flow on temperature, HF=f(T), the range (composition, temperature) of the occurrence of miscibility gap, the values of lower critical solution temperature (LCST), and critical concentration were determined. On the basis of the experimentally determined specific heat capacity data the partial molar heat capacities (Cp,2) of DPnP in the mixtures with water were calculated. Analyzing changes in the course ofCp,2=f(x2)function, the boundary of transition from a homogeneous solution was determined, in which the monomers of amphiphile dominate, to the region, in which aggregates of the cluster type appear.

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