On the blistering of thermo-sensitive hydrogel: the volume phase transition and mechanical instability

Soft Matter ◽  
2019 ◽  
Author(s):  
Tong Shen ◽  
Jian Kan ◽  
Eduard Benet ◽  
Franck J. Vernerey
Keyword(s):  
Phase Transition ◽  
Temperature Sensitive ◽  
Volume Phase Transition ◽  
Mechanical Instability ◽  
Volume Phase ◽  
Physical Mechanisms

This paper explores the physical mechanisms responsible for the appearance of small blisters on the surface of temperature sensitive hydrogels as they deswell rapidly during their volume phase transition.

Volume phase transition induced by temperature sensitive DL-amino acid methyl ester side chain based copolymer gels

2000 ◽  
Vol 3 (3) ◽  
pp. 381-387 ◽  
Author(s):  
Akihiro Hiroki ◽  
Hideaki Iwakami ◽  
Masaru Yoshida ◽  
Takeshi Suwa ◽  
Masaharu Asano ◽  
...  
Keyword(s):  
Phase Transition ◽  
Amino Acid ◽  
Methyl Ester ◽  
Acid Methyl Ester ◽  
Side Chain ◽  
Temperature Sensitive ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
Acid Methyl ◽  
Amino Acid Methyl Ester

Temperature-Sensitive Nanogels PNIPAAm/DMA Prepared and Research

2012 ◽  
Vol 465 ◽  
pp. 141-145
Author(s):  
Hai Yan Wang ◽  
Qian Liao ◽  
Qiao Lan Shao ◽  
Gao Qiu ◽  
Xi Hua Lu
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Synthesis And Characterization ◽  
Temperature Sensitive ◽  
Volume Phase Transition ◽  
Volume Phase ◽  
New Class ◽  
Copolymer Gels ◽  
Temperature Controlled

There have much study about thermo-responsive nanogels,which exhibit temperature-controlled volume phase transitions.There have been few reports,however,of electrostatically neutral,thermosensitive nanogels with a high composition of hydrophilic monomer.Here,we describe the synthesis and characterization of a new class of nonionic copolymer nanogels based on N-ispropylacrylamide(NIPAM) and N,N-dimethylacrylamide(DMA),wich exhibit tunable volume phase transition temperatures.And increasing percentages of DMA in copolymer gels raises the LCST,and attenuates and broadens the volume phases transition.Through DLS, AFM and UV-Vis measurement it's size,shape and VPTTs.The character of nonionic NIPAM/DMA nanogels show it's tunable phase transitions promise to be useful for applicatipns in biotechnology and medicine.

scholarly journals Volume Phase Transition in Gels: Its Discovery and Development

Gels ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 22
Author(s):  
Karel Dušek ◽  
Miroslava Dušková-Smrčková
Keyword(s):  
Phase Transition ◽  
Theoretical Models ◽  
Fine Tuning ◽  
Gibbs Energy Function ◽  
Relaxation Processes ◽  
Volume Phase Transition ◽  
Mechanical Instability ◽  
Volume Phase ◽  
History Of ◽  
Maxwell Construction

The history of volume phase transition of responsive gels from its theoretical prediction to experimental discovery was described and the major role of mixing Gibbs energy function in theoretical models was stressed. For detailed analysis and fine tuning of the volume phase transition, the generalized Flory–Huggins model with concentration and temperature dependent interaction function coupled with Maxwell construction as a tool is very suitable. Application of expansive stresses can uncover the potential of various swelling gels for volume phase transition. Experimentally, the abrupt, equilibrium-controlled phase transition is often hard to achieve due to passage of gel through states of mechanical instability and slow relaxation processes in macroscopic objects.

scholarly journals Investigation of the Effects of Different Hydrophilic and Hydrophobic Comonomers on the Volume Phase Transition Temperatures and Thermal Properties of N-Isopropylacrylamide-Based Hydrogels

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Ahmet Okudan ◽  
Abdullah Altay
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Pure Water ◽  
Thermal Analyses ◽  
Temperature Sensitive ◽  
Glass Temperature ◽  
Volume Phase Transition ◽  
Swelling Properties ◽  
Volume Phase ◽  
Swelling Equilibrium

In this work, a series of thermally responsive terpolymers of N-isopropylacrylamide (NIPA) with three different comonomer contents was synthesized, and their swelling behaviour was studied as a function of composition and temperature. Temperature-sensitive, random cross-linked terpolymers of NIPA were prepared from methyl methacrylate (MMA), N-tert-butylacrylamide (NTBA), and acrylic acid (AA) using a free radical polymerization method. In the synthesis of terpolymer hydrogels, N,N-methylene bisacrylamide (BIS) was used as cross-linkers and ammonium persulfate (APS) as initiator. The NIPA content of the monomer feed varied from 80 to 50 mol %, and other comonomer feed varied from 40 to 5 mol %. The swelling equilibrium of these hydrogels was studied as a function of temperature and hydrophobic and hydrophilic comonomer contents. The swelling properties of the polymers were investigated in pure water at temperatures from 10 to 80°C. All of the synthesized gels were found to be sensitive to temperature. Glass transition temperature analyses and thermal analyses of the synthesized hydrogels were studied. The volume phase transition temperature and the swelling equilibrium (r) values of NIPA-based hydrogels synthesized in different feed ratios and in varying monomer contents were found in the range of 17–52°C and 14–51 g H2O/g polymer, respectively. The glass temperature (Tg) of the NIPA/AA/(MMA or NTBA) hydrogels synthesized with feed ratios of 50/40/10 was found to be 133 or 142°C, respectively. The initial and the end degradation that were determined for hydrogels at high temperatures indicated the quite good thermal stability of hydrogels. When the mass loss of the synthesized hydrogels was 50%, the temperatures were measured between 247 and 258°C.

Triply-responsive OEG-based microgels and hydrogels: Regulation of swelling ratio, volume phase transition temperatures and mechanical properties

2021 ◽  
Author(s):  
Dongdong Lu ◽  
Mingning Zhu ◽  
Jing Jin ◽  
Brian R. Saunders
Keyword(s):  
Phase Transition ◽  
Biomedical Engineering ◽  
Volume Phase Transition ◽  
Swelling Ratio ◽  
Transition Temperatures ◽  
Ph Responsive ◽  
Network Systems ◽  
Volume Phase ◽  
Phase Transition Temperatures ◽  
Volume Swelling

Thermally- and pH-responsive microgels (MGs) and hydrogels are fascinating network systems that have been applied in biomedical engineering and sensing. The volume-swelling ratio (Q) and the volume-phase transition temperatures (VPTTs)...

scholarly journals Accounting for Cooperativity in the Thermotropic Volume Phase Transition of Smart Microgels

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 42
Author(s):  
Simon Friesen ◽  
Yvonne Hannappel ◽  
Sergej Kakorin ◽  
Thomas Hellweg
Keyword(s):  
Phase Transition ◽  
Interaction Parameter ◽  
Quantitative Description ◽  
Water Molecules ◽  
Volume Phase Transition ◽  
Network Chain ◽  
Solvent Interaction ◽  
Volume Phase ◽  
The Cross ◽  
Interaction Parameter Χ

A full quantitative description of the swelling of smart microgels is still problematic in many cases. The original approach of Flory and Huggins for the monomer–solvent interaction parameter χ cannot be applied to some microgels. The reason for this obviously is that the cross-linking enhances the cooperativity of the volume phase transitions, since all meshes of the network are mechanically coupled. This was ignored in previous approaches, arguing with distinct transition temperatures for different meshes to describe the continuous character of the transition of microgels. Here, we adjust the swelling curves of a series of smart microgels using the Flory–Rehner description, where the polymer–solvent interaction parameter χ is modeled by a Hill-like equation for a cooperative thermotropic transition. This leads to a very good description of all measured microgel swelling curves and yields the physically meaningful Hill parameter ν. A linear decrease of ν is found with increasing concentration of the cross-linker N,N′-methylenebisacrylamide in the microgel particles p(NIPAM), p(NNPAM), and p(NIPMAM). The linearity suggests that the Hill parameter ν corresponds to the number of water molecules per network chain that cooperatively leave the chain at the volume phase transition. Driven by entropy, ν water molecules of the solvate become cooperatively “free” and leave the polymer network.

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