Effect of Methanol/Water Mixtures on the Lower Critical Solution Temperature of Poly(N-isopropylacrylamide)

2014 ◽  
Vol 1622 ◽  
pp. 25-30 ◽  
Author(s):  
Sanket A. Deshmukh ◽  
Ganesh Kamath ◽  
Derrick C. Mancini ◽  
Subramanian K.R.S. Sankaranarayanan
Keyword(s):  
Mole Fraction ◽  
Lower Critical Solution Temperature ◽  
Md Simulations ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Radius Of Gyration ◽  
Solvation Dynamics ◽  
Water Mixture ◽  
Critical Solution Temperature ◽  
Lcst Behavior

ABSTRACTPoly(N-isopropylacrylamide) (PNIPAM) is a thermo-sensitive polymer that exhibits a lower critical solution temperature (LCST) around 305 K. Below the LCST, PNIPAM is soluble in water and above this temperature polymer chains collapse prior to aggregation. In the presence of methanol, electron paramagnetic resonance (EPR) spectroscopy suggests that, LCST of PNIPAM is depressed up to certain mole fraction of methanol (0.35 mole fraction) and it is speculated that addition of methanol affects the PNIPAM-water interactions. Above 0.35 mole fraction of methanol, LCST gets elevated to temperatures above ∼305 K (32°C) and cannot be detected up to 373 K (100 °C). The atomistic origin of this co-solvency effect on the LCST behavior is not completely understood. In the present study, we have used molecular dynamics (MD) simulations to investigate the effect of methanol-water mixtures on conformational transitions and the LCST of PNIPAM. We employ two different force fields i.e. polymer consistent force-field (PCFF) and CHARMM to study solvation dynamics and the PNIPAM LCST phase transition in various methanol-water mixture compositions (0.018, 0.09, 0.27, 0.5, and 0.98 mole fractions). Simulations are conducted at fully atomistic level for three different temperatures (260, 278, and 310 K) and radius of gyration (Rg) of PNIPAM chains was computed for determination of LCST behavior of PNIPAM.

Meso-scale Simulations of Poly(N-isopropylacrylamide) Grafted Architectures

2014 ◽  
Vol 1619 ◽  
Author(s):  
Sanket A. Deshmukh ◽  
Ganesh Kamath ◽  
Derrick C. Mancini ◽  
Subramanian K.R.S. Sankaranarayanan ◽  
Wei Jiang
Keyword(s):  
Conformational Dynamics ◽  
Md Simulations ◽  
Polymer Chains ◽  
Effect Of Temperature ◽  
Solution Temperature ◽  
Radius Of Gyration ◽  
Core Particle ◽  
Thermosensitive Polymer ◽  
Critical Solution Temperature ◽  
Different Diameters

ABSTRACTPoly(N-isopropylacrylamide) (PNIPAM) is a thermosensitive polymer that is well-known for its behavior at a lower critical solution temperature (LCST) around 305 K. Below the LCST, PNIPAM is soluble in water, and above this temperature, polymer chains collapse and transform into a globule state. The conformational dynamics of single chains of polymer in a solution is known to be different from those of grafted structures that comprise of an ensemble of such single chains. In this study, we have carried out MD simulations of a mesoscopic nanostructure of PNIPAM polymer chains consisting of 60 monomer units grafted onto gold nanoparticles of different diameters, to study the effect of temperature and core particle size on the polymer conformations. Additionally, we have also studied the effect of grafting density on the coil-to-globule transition exhibited by PNIPAM through the LCST. The systems investigated consisted of ∼3 and ∼6 million atoms. Simulations were carried out below and above the LCST of PNIPAM, at 275K and 325K. Simulation trajectories were analyzed for radius of gyration of PNIPAM chains.

scholarly journals Atomistic simulation for coil-to-globule transition of poly(2-dimethylaminoethyl methacrylate)

Soft Matter ◽  
2015 ◽  
Vol 11 (12) ◽  
pp. 2423-2433 ◽  
Author(s):  
Sa Hoon Min ◽  
Sang Kyu Kwak ◽  
Byeong-Su Kim
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Lower Critical Solution Temperature ◽  
Atomistic Simulation ◽  
Md Simulations ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Dimethylaminoethyl Methacrylate

We investigate the coil-to-globule transition of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) in the aqueous solution through the lower critical solution temperature (LCST) by atomistic molecular dynamics (MD) simulations.

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.

scholarly journals Influence of cyclodextrin on the UCST- and LCST-behavior of poly(2-methacrylamido-caprolactam)-co-(N,N-dimethylacrylamide)

2014 ◽  
Vol 10 ◽  
pp. 1951-1958 ◽  
Author(s):  
Alexander Burkhart ◽  
Helmut Ritter
Keyword(s):  
Free Radical ◽  
Nmr Spectroscopy ◽  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Radical Mechanism ◽  
Methacryloyl Chloride ◽  
Critical Solution Temperature ◽  
Free Radical Mechanism ◽  
Upper Critical Solution Temperature ◽  
Lcst Behavior

The monomer 2-methacrylamido-caprolactam (4) was synthesized from methacryloyl chloride (3) and racemic α-amino-ε-caprolactam (2). Copolymerization of 4 with N,N-dimethylacrylamide (5) was carried out by a free-radical mechanism using 2,2’-azobis(2-methylpropionitrile) (AIBN) as an initiator. The new copolymers show a lower critical solution temperature (LCST) in water and an upper critical solution temperature (UCST) in ethanol, 1-propanol, and 1-butanol. The solubility properties of the copolymers can be influenced significantly by the addition of randomly methylated β-cyclodextrin (CD). The complexation of the copolymers with CD, was confirmed by the use of ROESY-NMR-spectroscopy.

Agglomeration Dynamics In Thermo-Sensitive Polymers Across The Lower Critical Solution Temperature: A Molecular Dynamics Simulation Study

2012 ◽  
Vol 1418 ◽  
Author(s):  
Sanket A. Deshmukh ◽  
Subramanian K.R.S. Sankaranarayanan ◽  
Derrick C. Mancini
Keyword(s):  
Molecular Dynamics ◽  
Lower Critical Solution Temperature ◽  
Polymer Chains ◽  
Dynamics Simulation ◽  
Solution Temperature ◽  
Strongly Correlated ◽  
Critical Solution Temperature ◽  
Significant Difference ◽  
Fundamental Insight ◽  
Dynamics Simulations

ABSTRACTPoly(N-isopropylacrylamide) (PNIPAM), a classic thermo-sensitive polymer, has a lower critical solution temperature (LCST) at ∼32°C. In this work we have used molecular dynamics simulations to understand the origin of the LCST and agglomeration of PNIPAM chains of 5 and 30 monomer units (5-mer and 30-mer). Experimentally, when the concentration of PNIPAM is >1 ppm, polymer chains after undergoing coil-to-globule transition above the LCST aggregates to yield a stable colloidal dispersion.In our study two PNIPAM chains, consisting of 30 monomer units each, were placed in a cubic simulation cell and were subsequently solvated. Simulations were carried out below and above the LCST, namely at 278 and 310K for 10ns. Simulated trajectories were analyzed for structural and dynamical properties of both PNIPAM and water. We observe coil-to-globule transition in PNIPAM above the LCST. We also find that the PNIPAM chains agglomerate above the LCST. We also observe entanglement in PNIPAM chains below the LCST. We also study agglomeration of 5 PNIPAM chains each consisting of 5 monomer units. There was no significant difference in polymer agglomeration behavior across the LCST for these short chain oligomers. The agglomeration behavior is thus strongly correlated to the size of the polymer chains. These results provide fundamental insight into the atomistic scale mechanism of PNIPAM agglomeration across the LCST.

A polyelectrolyte-containing copolymer with a gas-switchable lower critical solution temperature-type phase transition

2019 ◽  
Vol 10 (2) ◽  
pp. 260-266 ◽  
Author(s):  
Jin-Jin Li ◽  
Yin-Ning Zhou ◽  
Zheng-Hong Luo ◽  
Shiping Zhu
Keyword(s):  
Phase Transition ◽  
Cloud Point ◽  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Type Phase

A polyelectrolyte-containing copolymer with a CO2/N2-switchable cloud point, resulting from the gas-induced alternation of hydrophilicity, was prepared.

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