scholarly journals Smart Hydrogels: Preparation, Characterization, and Determination of Transition Points of Crosslinked N-Isopropyl Acrylamide/Acrylamide/Carboxylic Acids Polymers

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 113
Author(s):  
Yasemin Işıkver ◽  
Dursun Saraydın
Keyword(s):  
The Body ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Isopropyl Acrylamide ◽  
Different Temperatures ◽  
Swelling Characteristics ◽  
Swelling Studies ◽  
Transition Points ◽  
Tga And Dsc

Smart hydrogels (SH) were prepared by thermal free radical polymerization of N-isopropyl acrylamide (NIPAAm), acrylamide (AAm) with acrylic acid (A) or maleic acid (M), and N, N′-methylene bisacrylamide. Spectroscopic and thermal characterizations of SHs were performed using FTIR, TGA, and DSC. To determine the effects of SHs on swelling characteristics, swelling studies were performed in different solvents, solutions, temperatures, pHs, and ionic strengths. In addition, cycle equilibrium swelling studies were carried out at different temperatures and pHs. The temperature and pH transition points of SHs are calculated using a sigmoidal equation. The pH transition points were calculated as 5.2 and 4.2 for SH-M and SH-A, respectively. The NIPAAm/AAm hydrogel exhibits a critical solution temperature (LCST) of 28.35 °C, while the SH-A and SH-M hydrogels exhibit the LCST of 34.215 °C and 28.798 °C, respectively, and the LCST of SH-A is close to the body. temperature. Commercial (CHSA) and blood human serum albumin (BHSA) were used to find the adsorption properties of biopolymers on SHs. SH-M was the most efficient SH, adsorbing 49% of CHSA while absorbing 16% of BHSA. In conclusion, the sigmoidal equation or Gaussian approach can be a useful tool for chemists, chemical engineers, polymer and plastics scientists to find the transition points of smart hydrogels.

scholarly journals Stimuli Responsive Hydrogels: NIPAM/AAm/Carboxylic Acid Polymers

2019 ◽  
Vol 27 (2) ◽  
pp. 155-184 ◽  
Author(s):  
Yasemin Işikver ◽  
Dursun Saraydin
Keyword(s):  
Thermal Analyses ◽  
The Body ◽  
Polymerization Reaction ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Scanning Calorimetry ◽  
Equilibrium Swelling ◽  
Different Temperatures ◽  
Swelling Studies ◽  
Responsive Hydrogels

Abstract Stimuli-responsive hydrogels (SRH) were prepared by using monomers (i.e. N-isopropyl acrylamide; NIPAM and acrylamide; AAm), co-monomers (i.e. methacrylic acid; MPA or mesaconic acid; MFA) and a crosslinker (N, N’-methylene bisacrylamide; N-Bis). SRH have been prepared by thermal free radical polymerization reaction in aqueous solution. Spectroscopic and thermal analyses such as Fourier Transform Infrared Spectroscopy, thermogravimetric analysis and differential scanning calorimetry analysis were performed for SRH characterization. The equilibrium swelling studies by gravimetrically were carried out in different solvents, at the solutions, temperature, pH, and ionic strengths to determine their effect on swelling characteristic of the hydrogels. In addition, cycles equilibrium swelling studies were made with the solutions at different temperatures and at different pH. NIPAM/AAm hydrogel exhibits a lover critical solution temperature (LCST) at 28 oC, whereas NIPAM/AAm-MPA and NIPAM/AAm-MFA hydrogels exhibit a LCST at 31 C and 35 oC, respectively, and the LCST of NIPAM/AAm-MFA hydrogel is close to the body temperature.

Superabsorbent Nanohydrogels of Poly (N-Isopropyl Acrylamide-Co-Itaconic Acid) Grafted on Starch — Synthesis and Swelling Study

Nano LIFE ◽  
2016 ◽  
Vol 06 (02) ◽  
pp. 1650005 ◽  
Author(s):  
Karim Pourjamal ◽  
Marziyeh Fathi ◽  
Ali Akbar Entezami ◽  
Mohammad Hasanzadeh ◽  
Nasrin Shadjou
Keyword(s):  
Itaconic Acid ◽  
Starch Synthesis ◽  
Ammonium Persulfate ◽  
Solution Temperature ◽  
Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Dsc Studies ◽  
Isopropyl Acrylamide ◽  
Effects Of Ph

Biopolymer-based superabsorbent nanohydrogel consisting of N-isopropylacrylamide and itaconic acid (IA) was grafted on to starch backbone in an aqueous solution in the absence of the cross-linker agents. The copolymerization reaction occurred in the presence of ammonium persulfate (APS) as an initiator. The effect of N-isopropylacrylamide-to-IA ratio and different concentrations of initiator were investigated. The nanohydrogel composition was characterized by Fourier transform infrared spectroscopy (FTIR). The thermal stability was analyzed by Thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) studies were employed for determination of lower critical solution temperature in hydrogels. Dynamic light scattering analysis showed a narrow size distribution around 70–200[Formula: see text]nm for the synthesized nanohydrogels. The effects of pH on swelling behavior of the hydrogel were investigated. The obtained nanohydrogels, due to their pH and thermo dual sensitive properties, have the potential to be used in the drug delivery systems.

Determination of Lower Critical Solution Temperature of thermosensitive flocculants

2014 ◽  
Vol 69 ◽  
pp. 170-176 ◽  
Author(s):  
Marcin Lemanowicz ◽  
Andrzej Gierczycki ◽  
Wojciech Kuźnik ◽  
Rafał Sancewicz ◽  
Patrycja Imiela
Keyword(s):  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Critical Solution Temperature

scholarly journals Thermally responsive polymeric hydrogel brushes: synthesis, physical properties and use for the culture of chondrocytes

2006 ◽  
Vol 4 (12) ◽  
pp. 117-126 ◽  
Author(s):  
John Collett ◽  
Aileen Crawford ◽  
Paul V Hatton ◽  
Mark Geoghegan ◽  
Stephen Rimmer
Keyword(s):  
Crosslink Density ◽  
Cell Attachment ◽  
Viable Cell ◽  
Contact Angles ◽  
Polymer Chains ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Thermally Responsive ◽  
Isopropyl Acrylamide ◽  
Responsive Polymer

Hydrogel brushes are materials composed of a water-swollen network, which contains polymer chains that are grafted with another polymer. Using a thermally responsive polymer, poly( N -isopropyl acrylamide) (polyNIPAM), as the graft component we are able to maintain the critical solution temperature ( T crit ), independent of the overall composition of the material, at approximately 32°C. The change in swelling at T crit is a function of the amount of polyNIPAM in the system. However, there is a much smaller change in the surface contact angles at T crit . PolyNIPAM-based materials have generated considerable interest, as ‘smart’ substrates for the culture of cells and here, we show the utility of hydrogel brushes in cell culture. Chondrocytes attached to the hydrogel brushes and yielded viable cell cultures. Moreover, the chondrocytes could be released from the hydrogel brushes without the use of proteases by reducing the temperature of the cultures to below T crit to induce a change in the conformation of the polyNIPAM chain at T crit . The importance of the crosslink hydrogel component is illustrated by significant changes in cell attachment/cell viability as the crosslink density is changed.

THERMOSENSITIVE NANOPARTICLES CONJUGATING WITH CD34 ANTIBODY AND ITS SOLUTION PEROPERTIES

2006 ◽  
Vol 18 (05) ◽  
pp. 222-228 ◽  
Author(s):  
CHUN-TE TAO ◽  
TAI-HORNG YOUNG
Keyword(s):  
Controlled Release ◽  
Cloud Point ◽  
Lower Critical Solution Temperature ◽  
Homogeneous Solution ◽  
The Body ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Critical Solution Temperature ◽  
Human Cd34 ◽  
Collapse Temperature

Poly N-isopropylacrylamide (PNIPAAm) is a well-known temperature-sensitive polymer. When the temperature is higher than the lower critical solution temperature (LCST), PNIPAAm aquous solution is cloudy (phase separation occurred). In contrast, when the temperature is lower than the LCST, PNIPAAm is soluble in water (a homogeneous solution). The lower critical solution temperature (LCST) in aqueous solution of PNIPAAm was about 32~33°C. We prepared nano-scaled PNIPAAm particles containing carboxylic group on their surfaces by introducing acrylic acid monomer. The carboxylic groups were applied to conjugate with the amino group of the CD34 antibody. This immuno-conjugate can be applied on targeting the human CD34 positive cells, peripheral blood progenitor cells included, for cell purification and drug controlled release. In order to the active responding of controlled release of the conjugate in the body influenced by temperature, we hope to estimate the shifting of the gel-collapse temperature or cloud point of the immuno-conjugates by dynamic light scattering (DLS) and UV absorption. The results show that the gel-collapse temperature of the nano-particle was not significantly affected by the content of AA between 1.5~5 mol%. However, cloud point of the solution was elevated by the conjugation of CD34 antibody to 37°C. When CD34-conjugated particle was subsequently incorporated with recombinant FLT3-ligand, which is a smaller molecule compare to CD34 antibody, cloud point of the solution was not affected.

scholarly journals Switchable Wettability of Poly(NIPAAm-co-HEMA-co-NMA) Coated PET Fabric for Moisture Management

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 100 ◽  
Author(s):  
Shamik Chaudhuri ◽  
Chang-Mou Wu
Keyword(s):  
Moisture Absorption ◽  
Optical Transmittance ◽  
Solution Temperature ◽  
Temperature Property ◽  
Water Contact ◽  
Critical Solution Temperature ◽  
Pet Fabric ◽  
Moisture Management ◽  
Different Temperatures ◽  
Coated Fabrics

In this study, we synthesized a random poly[(N-isopropylacrylamide)-co-(2-hydroxyethylmethacrylate)-co-(N-methylolacrylamide)] [poly(NIPAAm-co-HEMA-co-NMA)] copolymer through free-radical polymerization. The NIPAAm, HEMA and NMA moieties were framed to provide thermoresponsiveness, water absorption and retention control, and chemical cross-linking to achieve stability in aqueous medium, respectively. The copolymer showed a significant change in optical transmittance with a variation in temperature due to the change in volume (i.e., hydrophilic/hydrophobic) between 25 °C and 40 °C, attributed to the lower critical solution temperature property of the NIPAAm moiety. The copolymers were wire-bar-coated onto polyethylene terephthalate (PET) fabric. Variation in the water contact angle affirmed the switchable wettability due to the change in temperature. We tested the coated fabrics for moisture absorption and release at different temperatures. The results at 20 °C and 37 °C indicated that the P2 copolymer had the highest moisture absorption and release capability. Therefore, the copolymers with tailored properties can be used as smart textiles for activity specific clothing.

scholarly journals Upper or lower critical solution temperature, or both? Studies on cationic copolymers of N-isopropylacrylamide

2015 ◽  
Vol 6 (16) ◽  
pp. 3074-3082 ◽  
Author(s):  
Erno Karjalainen ◽  
Vladimir Aseyev ◽  
Heikki Tenhu
Keyword(s):  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Trimethylammonium Chloride ◽  
Solution Properties ◽  
Critical Solution Temperature ◽  
Isopropyl Acrylamide ◽  
Cationic Copolymers

The solution properties of statistical copolymers of N-isopropyl acrylamide (NIPAm) and cationic (3-acrylamidopropyl) trimethylammonium chloride (AMPTMA) have been studied.

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