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Phase diagrams of smart copolymers poly(N-isopropylacrylamide) and poly(sodium acrylate).

Zarzyka I, Di Lorenzo ML, Pyda M - ScientificWorldJournal (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, Poland.

ABSTRACT
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.

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((a), (b)) TM-DSC thermogram of gel/water system in equilibrium swelling degree: (a) PNIPA/water (10%/90%) and (b) PNIPA-SA (40%/60%). Onset values of LCST were taken from the TM-DSC plots (reversing heat flow) upon first and second heating at 5°C/min. Cooling was performed with 10 K/min by standard DSC. Endotherms around 0°C on heating and exotherms around −30°C on cooling are related to melting and crystallization of water, respectively. (c) Experimental, reversing heat capacity of the 10%/90% PNIPA/water and their vibrational baseline, Cp (vibrational) [44, 45].
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fig4: ((a), (b)) TM-DSC thermogram of gel/water system in equilibrium swelling degree: (a) PNIPA/water (10%/90%) and (b) PNIPA-SA (40%/60%). Onset values of LCST were taken from the TM-DSC plots (reversing heat flow) upon first and second heating at 5°C/min. Cooling was performed with 10 K/min by standard DSC. Endotherms around 0°C on heating and exotherms around −30°C on cooling are related to melting and crystallization of water, respectively. (c) Experimental, reversing heat capacity of the 10%/90% PNIPA/water and their vibrational baseline, Cp (vibrational) [44, 45].

Mentions: For better results, the heating rate should be as slow as possible. Figures 4(a) and 4(b) show two examples of results of reversing heat flow and total heat flow from TM-DSC measurements for demixing/mixing process of polymer/water system: PINIPA (10% : 90%) (Figure 4(a)) and PNIPA-SA (40% : 60%) (Figure 4(b)).


Phase diagrams of smart copolymers poly(N-isopropylacrylamide) and poly(sodium acrylate).

Zarzyka I, Di Lorenzo ML, Pyda M - ScientificWorldJournal (2014)

((a), (b)) TM-DSC thermogram of gel/water system in equilibrium swelling degree: (a) PNIPA/water (10%/90%) and (b) PNIPA-SA (40%/60%). Onset values of LCST were taken from the TM-DSC plots (reversing heat flow) upon first and second heating at 5°C/min. Cooling was performed with 10 K/min by standard DSC. Endotherms around 0°C on heating and exotherms around −30°C on cooling are related to melting and crystallization of water, respectively. (c) Experimental, reversing heat capacity of the 10%/90% PNIPA/water and their vibrational baseline, Cp (vibrational) [44, 45].
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4150473&req=5

fig4: ((a), (b)) TM-DSC thermogram of gel/water system in equilibrium swelling degree: (a) PNIPA/water (10%/90%) and (b) PNIPA-SA (40%/60%). Onset values of LCST were taken from the TM-DSC plots (reversing heat flow) upon first and second heating at 5°C/min. Cooling was performed with 10 K/min by standard DSC. Endotherms around 0°C on heating and exotherms around −30°C on cooling are related to melting and crystallization of water, respectively. (c) Experimental, reversing heat capacity of the 10%/90% PNIPA/water and their vibrational baseline, Cp (vibrational) [44, 45].
Mentions: For better results, the heating rate should be as slow as possible. Figures 4(a) and 4(b) show two examples of results of reversing heat flow and total heat flow from TM-DSC measurements for demixing/mixing process of polymer/water system: PINIPA (10% : 90%) (Figure 4(a)) and PNIPA-SA (40% : 60%) (Figure 4(b)).

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Rzeszow University of Technology, 35-959 Rzeszow, Poland.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus