NMR study of poly(N-isopropylacrylamide) gels near phase transition

Tokuhiro, Tadashi; Amiya, Takayuki; Mamada, Akira; Tanaka, Toyoichi

doi:10.1021/ma00010a046

Cited by 203 publications

(159 citation statements)

References 12 publications

Supporting

Mentioning

147

Contrasting

Order By: Relevance

“…The NMR spectra of the different polymers produced in the current study were in agreement with data published by several other authors [37,38]. The presence of an MBA moiety in polymers P1-P3 was confirmed by the presence of broad weak signals corresponding to the methylidene protons around 4.4 ppm, which were similar to those of the substrate and chemical shifts published by Zhang et al [39].…”

Section: Discussionsupporting

confidence: 91%

Synthesis, evaluation and release studies of NIPA nanopolymers presumed for temperature-controlled drug delivery

Gasztych

Valh

Kokol

et al. 2016

J Sol-Gel Sci Technol

View full text Add to dashboard Cite

The copolymers of N-isopropyl acrylamide (NIPA) have been studied extensively as drug carriers for antibacterial, cardiovascular, cytostatic, local anesthetic, and nonsteroidal anti-inflammatory agents, to deliver the required therapeutic effect. The aim of this work was to evaluate the effect of a series of newly synthesized thermosensitive polymeric NIPA derivatives on the release rate of naproxen sodium (NS) from hydrogels composed of hydroxypropyl methylcellulose (HPMC). NIPA derivatives P1-P4 were synthesized by precipitation polymerization without an emulsifier, and their structures were evaluated by NMR spectroscopy. Four formulations were prepared with NS (FP1-FP4), and rate of NS release from these systems was evaluated using a modified pharmacopeial method at 22 and 42°C. The release rate of NS followed a similar trend in all four of the formulations assessed at 22°C, which was the same as the reference formulation. However, the release rate of NS at 42°C was clearly faster in the samples containing the thermosensitive polymers P1-P4 compared with the reference formulation. These results clearly demonstrate that the use of thermosensitive polymeric derivatives of NIPA can increase the release rate of NS from hydrophilic gels based on HPMC.Graphical Abstract Diversity of release courses of naproxen sodium evaluated in formulation containing poly(ethylene glycol) dimethacrylate (PDA, left), and comparison of half-release times (T HR , right) of naproxen sodium formulations containing various thermosensitive polymers P1-P4.

show abstract

Section: Discussionsupporting

confidence: 91%

Synthesis, evaluation and release studies of NIPA nanopolymers presumed for temperature-controlled drug delivery

Gasztych

Valh

Kokol

et al. 2016

J Sol-Gel Sci Technol

View full text Add to dashboard Cite

show abstract

“…At a temperature below the LCST, a large expansion of the network leads to high absorption (presence of hydrophilic groups-CONH). At a temperature above the LCST increased system entropy occurs [29][30]. Swelling decreases due to hydrophobic interactions of hydrophobic groups of the hydrogels that are dominant.…”

Section: Study Of the Swellingmentioning

confidence: 99%

Synthesis, rheological behavior and swelling properties of copolymer hydrogels based on poly(N-isopropylacrylamide) with hydrophilic monomers

Seddiki¹,

Aliouche²

2013

Bull. Chem. Soc. Eth.

View full text Add to dashboard Cite

ABSTRACT. In this study, hydrogels of poly(N-isopropylacrylamide-co-acrylamide) and poly(Nisopropylacrylamide-co-acrylic acid) having a thermoresponsive character were prepared by aqueous free-radical co-polymerization using the ammonium persulfate/N,N,N', N'-tetramethylethylenediamine (APS/TEMED) redoxpair initiator system in the presence of N,N'-methylenebisacrylamide (MBAAm) crosslinker. (NIPAAm-co-AAm) and (NIPAAm-co-AAc) hydrogels with different thermoresponsive properties were obtained by fixing the initial NIPAAm/AAm mole ratio and and (NIPAAm-co-AAc) mole ratio to 80/20 and changing the crosslinker concentration. The copolymers were characterized with infrared spectroscopy (IR) and differential scanning calorimetry (DSC) techniques. The swelling response of the copolymers networks as a function of time, temperature and swelling environment has been observed to be dependent on both structural aspects of the polymers and swelling environment. The swelling has been observed to be decrease with increase in MBAAm in the copolypolymers networks. Rheological behavior was studies in oscillatory module. All copolymers have a viscoelastic behaviour. We note that the elastic modulus G' increases with increasing hydrophilic monomers.

show abstract

“…7 The overall contribution to the free energy of the gel system is negative, leading to this spontaneous and reversible behavior at this critical temperature.…”

Section: Introductionmentioning

confidence: 97%

Thermo‐sensitive swelling behavior in crosslinked N‐isopropylacrylamide networks: Cationic, anionic, and ampholytic hydrogels

Grainger

1993

J of Applied Polymer Sci

View full text Add to dashboard Cite

SYNOPSISCrosslinked polymer networks of N-isopropylacrylamide ( NiPAAm) containing small amounts of either anionic or cationic comonomers, or mixtures of both were fabricated and characterized in terms of their aqueous swelling and critical behavior. These gels demonstrate critical transition temperatures in aqueous media between a highly solvated, swollen gel state and a collapsed, dehydrated network over temperature ranges comparable to that of pure NiPAAm, with modifications of gel critical points and respective temperature ranges dependent upon comonomer type and content. Copolymer gel swelling ratios are significantly larger than those reported for pure homopolymer NiPAAm gels, even when only 0.5 mol % of comonomer is incorporated. At temperatures exceeding the collapse transition point, all copolymer gels collapse to a state of nearly complete dehydration, demonstrating short-time collapsed-state swelling ratios far lower than those of pure NiPAAm networks. Collapse kinetics for the ionomeric gels are much more rapid than those of pure NiPAAm, achieving collapse state equilibrium on time scales of seconds. Swelling behavior as a function of pH, buffer type, ionic strength, crosslinking, and temperature is detailed over a range of copolymer compositions.

show abstract

NMR study of poly(N-isopropylacrylamide) gels near phase transition

Cited by 203 publications

References 12 publications

Synthesis, evaluation and release studies of NIPA nanopolymers presumed for temperature-controlled drug delivery

Synthesis, evaluation and release studies of NIPA nanopolymers presumed for temperature-controlled drug delivery

Synthesis, rheological behavior and swelling properties of copolymer hydrogels based on poly(N-isopropylacrylamide) with hydrophilic monomers

Thermo‐sensitive swelling behavior in crosslinked N‐isopropylacrylamide networks: Cationic, anionic, and ampholytic hydrogels

Contact Info

Product

Resources

About