10431-99-9Relevant articles and documents
Microcalorimetric Study of the Temperature-Induced Phase Separation in Aqueous Solutions of Poly(2-isopropyl-2-oxazolines)
Diab, Charbel,Akiyama, Yoshitsugu,Kataoka, Kazunori,Winnik, Francoise M.
, p. 2556 - 2562 (2004)
The effect of temperature on aqueous solutions of poly(2-isopropyl-2- oxazoline) (PIPOZ) samples of molecular weights ranging from 1900 to 5700 g mol-1 was monitored by turbidimetry, high-sensitivity microcalorimetry (HS DSC), and pressure perturbation calorimetry (PPC) from 10 to 80°C. The polymers were soluble in cold water and underwent phase separation at TCP ～ 45-63°C, depending on their molecular weight. The phase transition was endothermic, with an enthalpy change ranging from 0.36 ± 0.01 to 1.16 ± 0.01 kcal mol-1. The coefficient of thermal expansion of PIPOZ in water (αpol), determined by PPC, underwent a sharp increase at the temperature corresponding to the onset of phase transition, reaching a maximum value at T ～ T CP. Microcalorimetric measurements were carried out with solutions of PIPOZ samples in D2O and in aqueous NaCl solutions. The thermodynamic and volumetric changes associated with the phase transition of aqueous PIPOZ solutions are compared to those of aqueous solutions of two related polymers, poly(vinylcaprolactam) and poly(N-isopropylacrylamide) (PNIPAM), a polymer structurally related to PIPOZ that undergoes a phase transition in water at ～31°C.
In Vitro Assessment of the Hydrolytic Stability of Poly(2-isopropenyl-2-oxazoline)
Jerca, Florica Adriana,Jerca, Valentin Victor,Hoogenboom, Richard
, p. 5020 - 5032 (2021/11/24)
Poly(2-isopropenyl-2-oxazoline) (PiPOx) is emerging as a promising, versatile polymer platform to design functional materials and particularly biomaterials that rely on the hydrophilic character of the 2-oxazoline side units. To be able to assess the applicability of PiPOx in a biomedical context, it is essential to understand its stability and degradation behavior in physiological conditions. In the present work, the hydrolytic stability of PiPOx was systematically investigated as a function of pH during incubation in various buffers. PiPOx was found to be stable in deionized water (pH 6.9), to have good stability in basic conditions (pH 8 and 9), to be satisfactorily stable in neutral conditions (pH 7.4), and to have moderate to low stability in acidic conditions (decreases drastically from pH 6 to pH 1.2). At pH 4, PiPOx formed a crosslinked network in a timeframe of hours, while at pH 1.2, PiPOx was transformed to a water-soluble poly(N-(2-hydroxyethyl)methacrylamide) type of structure over the course of 2 weeks. In vitro stability assays were performed in phosphate-buffered saline (pH 7.4), simulated body fluid (SBF) (pH 7.4), simulated saliva (pH 6.4), simulated intestinal fluid (pH 6.8), and plasma (pH 7.4) revealing that PiPOx is stable in these SBFs up to 1 week of incubation. When incubated in simulated gastric fluid (pH 1.2), PiPOx exhibited a similar degradation behavior to that observed in the buffer at pH 1.2, rendering a water-soluble structure. The presented results on the stability of PiPOx will be important for future use of PiPOx for the development of drug-delivery systems and biomedical applications, such as hydrogels.
Crystallisation-driven self-assembly of poly(2-isopropyl-2-oxazoline)-block-poly(2-methyl-2-oxazoline) above the LCST
Legros, Camille,De Pauw-Gillet, Marie-Claire,Tam, Kam Chiu,Taton, Daniel,Lecommandoux, Sébastien
, p. 3354 - 3359 (2015/05/05)
The solution behaviour in water of a polyoxazoline-type block copolymer, namely poly(2-isopropyl-2-oxazoline)-block-poly(2-methyl-2-oxazoline), denoted as P(iPrOx-b-MeOx), above the lower critical solution temperature (LCST) of the PiPrOx block was exploited to induce a temporary or permanent self-assembly. Spherical micelles were first obtained and could be disassembled in a reversible manner when kept for a short period of time (i.e. t 90 min) above the LCST, and cooled down to room temperature. In contrast, annealing the copolymer solution for more than 90 min at 65 °C induced the crystallisation of the PiPrOx block, as evidenced by wide angle X-ray scattering (WAXS) experiments. This crystallisation-driven self-assembly phenomenon resulted in different morphologies, including spherical and distorted crystallised micelles and micron-size fibers, their relative proportion varies with the annealing time. Formation of micron-size range fiber-like structures might be explained by the re-organization of parent crystallised micelles. The crystal structure, as determined by WAXS, appeared to be identical to that of the PiPrOx homopolymer.
Versatile synthesis of end-functionalized thermosensitive poly(2-isopropyl-2-oxazolines)
Park, Joon-Sik,Akiyama, Yoshitsugu,Winnik, Francoise M.,Kataoka, Kazunori
, p. 6786 - 6792 (2007/10/03)
The synthesis of several end-functionalized poly(2-isopropyl-2-oxazolines) (PiPrOx) has been achieved via cationic ring-opening polymerization of 2-isopropyl-2-oxazoline. Poly(2-isopropyl-2-oxazolines) bearing primary amino groups at one chain end (Me-PiP
Organoselenium-Induced Cyclization of Olefinic Imidates and Amides. Selective Synthesis of Lactams or Iminolactones
Toshimitsu, Akio,Terao, Keiji,Uemura, Sakae
, p. 2018 - 2026 (2007/10/02)
Lactams were formed selectively by the cyclization of olefinic imidates through the addition of a phenylseleno group to the double bond.Similar cyclization of olefinic amides, on the other hand, afforded either iminolactones or lactams depending on the st
Allenes. Part 44. Formation of Oxazolines and Benzoxazoles from Allenic nitriles and amides and from Phenylpropynenitrile.
Fomum, Z. Tanee,Nkengfack, A. Ephrem,Mpango, George W. P.,Landor, Stephen R.,Landor, Phyllis D.
, p. 901 - 924 (2007/10/02)
Michael addition of ethanolamines and 2-aminophenol to allenic nitriles, allenic amides and phenylpropynenitrile gives enaminic nitriles and amides which at 290 deg - 320 deg yield oxazolines and benzoxazoles.
