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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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Related in: MedlinePlus

TM-DSC thermograms of PNIPA-SA/water (20%/80%) system in equilibrium swelling degree, upon heating rate of 5 K/min and cooling rate of 10 K/min.
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fig2: TM-DSC thermograms of PNIPA-SA/water (20%/80%) system in equilibrium swelling degree, upon heating rate of 5 K/min and cooling rate of 10 K/min.

Mentions: TM-DSC measurements of the same sample have given somewhat different results (Figure 2). Only one peak has been noticed both on curve of total heat flow and on curve of reversing heat flow in contradistinction to DSC curve despite the same heating rate (5 K/min) (Figures 1 and 2). Figure 2 shows a comparison of total and reversing heat flow of demixing where endotherms are similar and the process is reversing. The demixing temperature (LCST) was estimated as onset temperature.


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

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

TM-DSC thermograms of PNIPA-SA/water (20%/80%) system in equilibrium swelling degree, upon heating rate of 5 K/min and cooling rate of 10 K/min.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig2: TM-DSC thermograms of PNIPA-SA/water (20%/80%) system in equilibrium swelling degree, upon heating rate of 5 K/min and cooling rate of 10 K/min.
Mentions: TM-DSC measurements of the same sample have given somewhat different results (Figure 2). Only one peak has been noticed both on curve of total heat flow and on curve of reversing heat flow in contradistinction to DSC curve despite the same heating rate (5 K/min) (Figures 1 and 2). Figure 2 shows a comparison of total and reversing heat flow of demixing where endotherms are similar and the process is reversing. The demixing temperature (LCST) was estimated as onset temperature.

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