Molecular weight and end group effects on the thermo-responsive property of oligomeric N-isopropylacrylamide

Li, Zhengzheng; Kim, Yon-Hwan; Min, Hyun Su; Han, Chang-Kwon; Huh, Kang Moo

doi:10.1007/s13233-010-0609-7

Cited by 18 publications

(20 citation statements)

References 22 publications

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“…Increasing the amount of amino end-groups, hydration behavior of PNIPAM changes due to the stronger interaction between amino groups and water molecules, preventing the formation of insoluble PNIPAM globule and therefore raises the T cp . A similar result was reported by Huh and coworkers [50] in which the LCSTs of the aqueous solution of the amino and hydroxyl-terminated PNIPAM shifted to lower temperatures as the polymer molecular weights increased. Additionally, they found that the amino group increased the LCST more significant than the hydroxyl group, in good agreement with our results as shown in Figure 7(B).…”

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionsupporting

confidence: 87%

“…Given end-group with higher hydrophobicity, PNIPAM formed aggregates below its LCST, which prompted a transition to occur into the insoluble globuleform at the lower temperature [6,51,52]. Indeed, PNIPAM aggregates have been demonstrated in the cold aqueous solutions of alkyl and aryl modified PNIPAM as reported by Duan et al [16] and Huh et al [50], respectively. However, the hydrophobic groups in the chain-end of PNIPAM can form a hydrophobic micellar structure if the end-introduced chains are long enough, which then become separated from the solvated PNIPAM chains and therefore do not make a hydrophobic contribution to the LCST.…”

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionmentioning

confidence: 92%

“…LCSTs are expected to be decreased with increasing molecular weight on the basis of the changes in the polymer-solvent interaction [48,49]. However, end-groups attached to the chain end can mitigate this trend or perhaps reverse by changing the hydrophobic/hydrophilic nature of the polymer [27,34,44,50].…”

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionmentioning

confidence: 99%

“…Additionally, they found that the amino group increased the LCST more significant than the hydroxyl group, in good agreement with our results as shown in Figure 7(B). On the other hand, the hydrophobic end-group effects on the T cp of PNIPAM can be explained by hydrophobic association [50], in which the driving force is the much lower solubility of the hydrophobic moiety in water. It is known that the liquid-solid phase transition is derived from the coil-globule transition of the PNIPAM chains in water at the LCST.…”

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionmentioning

confidence: 99%

See 3 more Smart Citations

Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties

Liu

Liao

Yang

et al. 2012

Designed Monomers and Polymers

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(2013) Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties, Designed Monomers and Polymers, 16:5, 465-474, DOI: 10.1080/15685551.2012 In this study, well-defined poly(N-isopropylacrylamide) (PNIPAM) with a bisalkyne end-group was synthesized by reversible addition-fragmentation chain transfer polymerization using 2-(2-(ethylthiocarbonothioylthio)-2-methylpropanoyl-oxy)ethyl 3,5-bis(prop-2-ynyloxy) benzoate (EMEB) as the chain transfer agent. The molecular weight and polydispersity index of polymer was determined by gel permeation chromatography (GPC). The linear increase in molecular weight with conversion, unimodal, and almost symmetrical peak in GPC trace together with low polydispersity indicated the controlled polymerization process of NIPAM mediated by EMEB. Subsequently, the Cu(I)-catalyzed [3 + 2] Huisgen cycloaddition between the end-group of polymer and azide derivatives was carried out to produce PNIPAM, in which the bisfunctional end-group was modified with phenyl, octyl, amido, and hydroxyl groups. After completing the click reaction, the structure of the polymer was characterized carefully by Fourier transform infrared spectroscopy (FTIR), 1 H NMR, and Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), indicating the complete consumption of alkyne end-groups. In addition, almost no change in molecular weight as well as the polydispersity was observed by comparison with the GPC traces of polymers before and after click reaction. The cloud point temperatures (T cp s) of the resulting PNIPAM derivatives in aqueous solution were investigated in detail by dynamic light scattering. The results showed that the values of T cp were ranged from 22 to 38°C, which depended largely on end-groups as well as the polymer molecular weights.

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Section: Thermoresponsivity Of Pnipams Before and After Click Reactionsupporting

confidence: 87%

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionmentioning

confidence: 92%

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionmentioning

confidence: 99%

Section: Thermoresponsivity Of Pnipams Before and After Click Reactionmentioning

confidence: 99%

See 2 more Smart Citations

Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties

Liu

Liao

Yang

et al. 2012

Designed Monomers and Polymers

View full text Add to dashboard Cite

show abstract

“…Some excellent studies on end group effects on the LCST have been done with homo PNIPAM [29,30], but there are few systematic studies of end group effects on diblock copolymers. One recent study of the collapse transition of a diblock copolymer, polystyrene-b-NIPAM [31], did report that it behaved differently from previously studied triblock copolymers [32,33].…”

Section: Introductionmentioning

confidence: 99%

Tuning thermoresponsive behavior of diblock copolymers and their gold core hybrids

Chen

Xiang

Tiwari

et al. 2013

Journal of Colloid and Interface Science

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Cathepsin B cleavable novel prodrug Ac‐Phe‐Lys‐PABC‐ADM enhances efficacy at reduced toxicity in treating gastric cancer peritoneal carcinomatosis

Shao

Liu

Hou

et al. 2011

Cancer

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Highly branched “smart” polymers have emerged as a unique class of polymers with wide‐ranging applications. Poly(N‐isopropylacrylamide) (pNIPAAm) is at the forefront of stimuli‐responsive polymers; however, few transition temperature‐modification methods of linear pNIPAAm have been explored in highly branched systems. In this study, the three primary techniques of transition temperature modification of linear pNIPAAm are investigated for their efficacy on highly branched polymers. Of these techniques, cosolvent‐mediated tacticity control demonstrates an effect opposite of that which is expected. Temperature transition control via end‐group modification shows a marked decrease in efficacy in highly branched systems, despite highly branched systems having more end groups per polymer. Copolymerization with hydrophilic comonomers exhibits varying changes in efficacy compared to linear analogs, lending insights into the specific effects on the structured water surrounding the copolymer. While copolymerization proved to be most versatile in changing the transition temperature, all of the techniques showed interesting secondary effects. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

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Molecular weight and end group effects on the thermo-responsive property of oligomeric N-isopropylacrylamide

Cited by 18 publications

References 22 publications

Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties

Well-defined poly(N-isopropylacrylamide) with a bifunctional end-group: synthesis, characterization, and thermoresponsive properties

Tuning thermoresponsive behavior of diblock copolymers and their gold core hybrids

Cathepsin B cleavable novel prodrug Ac‐Phe‐Lys‐PABC‐ADM enhances efficacy at reduced toxicity in treating gastric cancer peritoneal carcinomatosis

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