Thermo-responsive block copolymers with multiple phase transition temperatures in aqueous solutions

Strandman, Satu; Zhu, Xiaoxia

doi:10.1016/j.progpolymsci.2014.10.008

Cited by 132 publications

(122 citation statements)

References 176 publications

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“…The heating DSC curves in Figure (c), allows us to verify that water is present in three different environments into the hydrogels: bounded water, bulk water, and free water . Bounded water is present in the interface between water and the polymeric matrix, and presents the lowest melting temperature (around −18 °C).…”

Section: Resultsmentioning

confidence: 93%

“…For PUs containing high amount of PCL, PU(45:44:11), a tendency of the increase of water uptake with increasing temperature is observed. There are few reports in the literature about polymer/water systems that present an upper critical solution temperature (UCST) . In this case, the interactions between PCL segments could be responsible for this effect.…”

Section: Resultsmentioning

confidence: 99%

“…Thermo‐porosimetry consists of determining the water crystallization temperature into the hydrogel . The crystallization temperature of water present in the pores decreases as the pore diameter decreases in consequence of the intermolecular interactions between water and the polymer chains, and due to capillarity effect . Cooling DSC curves for the hydrogels and the crystallization temperature of sorbed water as a function of the PEG content are shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

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Thermo‐responsive polyurethane hydrogels based on poly(ethylene glycol) and poly(caprolactone): Physico‐chemical and mechanical properties

Fonseca

Trinca

Felisberti

2016

J of Applied Polymer Sci

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In this work, we present the synthesis and characterization of chemically crosslinked polyurethanes (PU) composed of poly(ethylene glycol) (PEG) and poly(caprolactone) diol (PCL-diol), as hydrophilic and hydrophobic segments respectively, poly(caprolactone) triol (PCL-triol), to induce hydrolysable crosslinks, and hexamethylene diisocyanate (HDI). The syntheses were performed at 45 8C, resulting in polyurethanes with different PEG/PCL-diol/PCL-triol mass fractions. All the PUs are able to crystallize and their thermal properties depend on the global composition. The water uptake capacities of the PU increase as the PEG amount increases. The water into hydrogels is present in different environments, as bounded, bulk and free water. The PU hydrogels are thermoresponsive, presenting a negative dependence of the water uptake with the temperature for PEG rich networks, which gradually changes to a positive behavior as the amount of poly(caprolactone) (PCL) segments increases. However, the water uptake capacity changes continuously without an abrupt transition. Scanning electron microscopy (SEM) analyses of the hydrogel morphology after lyophilization revealed a porous structure. Mechanical compression tests revealed that the hydrogels present good resilience and low recovery hysteresis when they are subject to cycles of compression-decompression. In addition, the mechanical properties of the hydrogels varies with the composition and crosslinking density, and therefore with the water uptake capacity. The PU properties can be tuned to fit for different applications, such as biomedical applications.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Thermo‐responsive polyurethane hydrogels based on poly(ethylene glycol) and poly(caprolactone): Physico‐chemical and mechanical properties

Fonseca

Trinca

Felisberti

2016

J of Applied Polymer Sci

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“…Our knowledge and understanding of thermo-responsive, water-soluble polymers showing a lower critical solution (LCST) behaviour [1][2][3][4][5][6] is, notwithstanding a number of remaining questions, 6 rather advanced compared to those exhibiting upper critical solution temperature (UCST) behaviour. [7][8][9] In fact, LCST behaviour is a common phenomenon of non-ionic polymers in aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

Effect of the zwitterion structure on the thermo-responsive behaviour of poly(sulfobetaine methacrylates)

Hildebrand

Laschewsky

Päch³

et al. 2017

Polym. Chem.

135

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A series of new sulfobetaine methacrylates, including nitrogen-containing saturated heterocycles, was synthesised by systematically varying the substituents of the zwitterionic group. Radical polymerisation via the RAFT (reversible addition-fragmentation chain transfer) method in trifluoroethanol proceeded smoothly and was well controlled, yielding polymers with predictable molar masses. Molar mass analysis and control of the end-group fidelity were facilitated by end-group labeling with a fluorescent dye. The polymers showed distinct thermo-responsive behaviour of the UCST (upper critical solution temperature) type in an aqueous solution, which could not be simply correlated to their molecular structure via an incremental analysis of the hydrophilic and hydrophobic elements incorporated within them. Increasing the spacer length separating the ammonium and the sulfonate groups of the zwitterion moiety from three to four carbons increased the phase transition temperatures markedly, whereas increasing the length of the spacer separating the ammonium group and the carboxylate ester group on the backbone from two to three carbons provoked the opposite effect. Moreover, the phase transition temperatures of the analogous polyzwitterions decreased in the order dimethylammonio > morpholinio > piperidinio alkanesulfonates. In addition to the basic effect of the polymers' precise molecular structure, the concentration and the molar mass dependence of the phase transition temperatures were studied. Furthermore, we investigated the influence of added low molar mass salts on the aqueous-phase behaviour for sodium chloride and sodium bromide as well as sodium and ammonium sulfate. The strong effects evolved in a complex way with the salt concentration. The strength of these effects depended on the nature of the anion added, increasing in the order sulfate < chloride < bromide, thus following the empirical Hofmeister series. In contrast, no significant differences were observed when changing the cation, i.e. when adding sodium or ammonium sulfate.

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“…In recent years, there is an increasing tendency towards the preparation of well-defined sequence-controlled polymers. 10,11 Smart polymers show rapid and reversible changes in response to small changes to their environment (e.g., pH, temperature, salt concentration, and co-solvent). Recently, new methodologies have emerged for multi-block copolymer synthesis based on one-pot sequential addition of monomers while tar-geting near full conversion per block, thus removing the need for intermediate purification steps.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular glycopolymers with thermo-responsive self-assembly and lectin binding

2015

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Thermo-responsive block copolymers with multiple phase transition temperatures in aqueous solutions

Cited by 132 publications

References 176 publications

Thermo‐responsive polyurethane hydrogels based on poly(ethylene glycol) and poly(caprolactone): Physico‐chemical and mechanical properties

Thermo‐responsive polyurethane hydrogels based on poly(ethylene glycol) and poly(caprolactone): Physico‐chemical and mechanical properties

Effect of the zwitterion structure on the thermo-responsive behaviour of poly(sulfobetaine methacrylates)

Supramolecular glycopolymers with thermo-responsive self-assembly and lectin binding

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