scholarly journals Free radical homopolymerization of a vinylferrocene/cyclodextrin complex in water

2010 ◽  
Vol 6 ◽  
Author(s):  
Helmut Ritter ◽  
Beate E Mondrzik ◽  
Matthias Rehahn ◽  
Markus Gallei
Keyword(s):  
Free Radical ◽  
Water Soluble ◽  
Solution Temperature ◽  
Cyclodextrin Complex ◽  
Scanning Calorimetry ◽  
Water Soluble Polymer ◽  
Critical Solution Temperature ◽  
H Nmr ◽  
Nmr Spectrometry ◽  
Cyclodextrin Cavity

We report the radical initiated homopolymerization of a soluble vinylferrocene cyclodextrin-complex in water. Uncomplexed vinylferrocene 1 and the corresponding homopolymer are hydrophobic and completely insoluble in water. Complexation of 1 with methyl-β-cyclodextrin 2 results in clearly water-soluble structures due to incorporation of the ferrocene moiety into the cyclodextrin cavity. After free radical polymerization of the water-soluble complexed monomer, corresponding to polyvinylferrocene (PVFc), the water-soluble polymer is obtained due to the host guest interactions. Those polymeric complexes are stable in water up to about 90 °C. Above this temperature the polymer precipitates due to decomplexation. The complex was investigated by 1H NMR spectrometry, dynamic light scattering (DLS), differential scanning calorimetry (DSC), and lower critical solution temperature (LCST) measurements.

scholarly journals EXTRACTION AND REEXTRACTION OF HISTIDINE AND RIBOFLAVIN BY N-VINYLCAPROLACTAME COPOLYMERS WITH 1-VINYL- AND 1-METHACRYLOYL-3,5-DIMETHYLPYROZOLE

2018 ◽  
Vol 59 (7) ◽  
pp. 55
Author(s):  
Maria S. Lavlinskaya ◽  
Gennadiy V. Shatalov ◽  
Nadezhda Ya. Mokshina ◽  
Oksana A. Pakhomova ◽  
Vyacheslav A. Kuznetsov
Keyword(s):  
Free Radical ◽  
Uv Spectroscopy ◽  
Aqueous Media ◽  
Radical Copolymerization ◽  
Water Soluble ◽  
Solution Temperature ◽  
Free Radical Copolymerization ◽  
Critical Solution Temperature ◽  
Two Phases ◽  
Degree Of Extraction

Copolymers of N-vinylcaprolactam (VC) with 1-vinyl-3,5-dimethylpyrazole (VDMP) and 1-methacryloyl-3,5-dimethylpyrazole (MDMP) were synthesized by free radical copolymerization  in dioxane with azodiisobutironitrole as initiator. Both water-soluble and water-insoluble copolymers were obtained. The copolymers compositions were determined by FTIR and UV-spectroscopy. The copolymerization constants were calculated and they were: for VC (М1)–VDMP, r1 = 0.65 ± 0.03, r2 = 0.43 ± 0.03; for VC (М1)–MDMP, r1 = 0.79 ± 0.04, r2 = 0.21 ± 0.02. These values show that VC (М1) exhibits somewhat higher activity compared to М2 and that the tendency toward alternation of comonomer units is more pronounced in VC–MDMP copolymers (r1r2 = 0.17) compared to VC–VDMP copolymers (r1r2 = 0.27). It was found that VC–VDMP copolymers are water-soluble at VC content higher than 75 mol %, and VC–MDMP copolymers at VC content higher than 88 mol %. The water-soluble copolymers based on VC have lower critical solution temperature. Their values are in range of 54-69 °C. Two-phases water-salts systems based on synthesized water-soludle thermoresponsive copolymers are proposed for histidine and riboflavin (re)extraction in aqueous media. It was found that extraction systems based on VC-VDMP copolymers are more efficient then VC-MDMP systems. Degree of extraction for both substances in a case of VC-VDMP copolymers achieved 96%. Reextraction carried out by thermoprecipitation of VC (co)polymers. It was shown that reextraction is more efficient at pH 7.6 and its degree achieved 61.7 % for histidine.

scholarly journals Synthesis of a thermoresponsive crosslinked MEO2MA polymer coating on microclusters of iron oxide nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alejandro Lapresta-Fernández ◽  
Alfonso Salinas-Castillo ◽  
Luis Fermín Capitán-Vallvey
Keyword(s):  
Iron Oxide ◽  
Synthesis Temperature ◽  
Water Soluble ◽  
Covalent Attachment ◽  
Solution Temperature ◽  
Tetraethylene Glycol ◽  
Critical Solution Temperature ◽  
Large Size ◽  
Transmission Electron ◽  
Azo Initiator

AbstractEncapsulation of magnetic nanoparticles (MNPs) of iron (II, III) oxide (Fe3O4) with a thermopolymeric shell of a crosslinked poly(2-(2-methoxyethoxy)ethyl methacrylate) P(MEO2MA) is successfully developed. Magnetic aggregates of large size, around 150–200 nm are obtained during the functionalization of the iron oxide NPs with vinyl groups by using 3-butenoic acid in the presence of a water soluble azo-initiator and a surfactant, at 70 °C. These polymerizable groups provide a covalent attachment of the P(MEO2MA) shell on the surface of the MNPs while a crosslinked network is achieved by including tetraethylene glycol dimethacrylate in the precipitation polymerization synthesis. Temperature control is used to modulate the swelling-to-collapse transition volume until a maximum of around 21:1 ratio between the expanded: shrunk states (from 364 to 144 nm in diameter) between 9 and 49 °C. The hybrid Fe3O4@P(MEO2MA) microgel exhibits a lower critical solution temperature of 21.9 °C below the corresponding value for P(MEO2MA) (bulk, 26 °C). The MEO2MA coating performance in the hybrid microgel is characterized by dynamic light scattering and transmission electron microscopy. The content of preformed MNPs [up to 30.2 (wt%) vs. microgel] was established by thermogravimetric analysis while magnetic properties by vibrating sample magnetometry.

scholarly journals Synthesis and characterization of PIL/pNIPAAm hybrid hydrogels

2016 ◽  
Vol 2 (1) ◽  
pp. 1-4
Author(s):  
Sylvia Pfensig ◽  
Daniela Arbeiter ◽  
Klaus-Peter Schmitz ◽  
Niels Grabow ◽  
Thomas Eickner ◽  
...  
Keyword(s):  
Mechanical Characterization ◽  
Heating Temperature ◽  
Controlled Drug Release ◽  
Solution Temperature ◽  
Scanning Calorimetry ◽  
Critical Solution Temperature ◽  
Temperature Range ◽  
Hybrid Hydrogels ◽  
Higher Temperature

AbstractIn this study, varying amounts of NIPAAm and an ionic liquid (IL), namely 1-vinyl-3-isopropylimidazolium bromide ([ViPrIm]+[Br]−), have been used to synthesize hybrid hydrogels by radical emulsion polymerization. Amounts of 70/30%, 50/50%, 30/70%, 15/85% and 5/95% (wt/wt) of PIL/pNIPAAm were used to produce hybrid hydrogels as well as the parental hydrogels. The adhesive strength was investigated and evaluated for mechanical characterization. Thermal properties of resulting hydrogels have been investigated using differential scanning calorimetry (DSC) in a default heating temperature range (heating rate 10 K min−1). The presence of poly ionic liquids (PIL) in the polymer matrix leads to a moved LCST (lower critical solution temperature) to a higher temperature range for certain hybrid hydrogels PIL/pNIPAAm. While pNIPAAm exhibits an LCST at 33.9 ± 0.3°C, PIL/pNIPAAm 5/95% and PIL/pNIPAAm 15/85% were found to have LCSTs at 37.6 ± 0.9°C and 52 ± 2°C, respectively. This could be used for controlled drug release that goes along with increasing body temperature in response to an implantation caused infection.

Development and Characterization of the Neuroregenerative Xanthohumol C/Hydroxypropyl-β-cyclodextrin Complex Suitable for Parenteral Administration

Planta Medica ◽  
2019 ◽  
Vol 85 (16) ◽  
pp. 1233-1241
Author(s):  
Michael Kirchinger ◽  
Lara Bieler ◽  
Julia Tevini ◽  
Michael Vogl ◽  
Elisabeth Haschke-Becher ◽  
...  
Keyword(s):  
Water Solubility ◽  
Pharmaceutical Research ◽  
Water Soluble ◽  
Complexing Agents ◽  
Cyclodextrin Complex ◽  
Scanning Calorimetry ◽  
In Vivo Experiments ◽  
Strong Candidate

AbstractThe chroman-like chalcone Xanthohumol C, originally found in hops, was demonstrated to be a potent neuroregenerative and neuroprotective natural product and therefore constitutes a strong candidate for further pharmaceutical research. The bottleneck for in vivo experiments is the low water solubility of this chalcone. Consequently, we developed and validated a suitable formulation enabling in vivo administration. Cyclodextrins were used as water-soluble and nontoxic complexing agents, and the complex of Xanthohumol C and 2-hydroxypropyl-β-cyclodextrin was characterized using HPLC, HPLC-MS, NMR, and differential scanning calorimetry. The water solubility of Xanthohumol C increases with increasing concentrations of cyclodextrin. Using 50 mM 2-hydroxypropyl-β-cyclodextrin, solubility was increased 650-fold. Furthermore, in vitro bioactivity of Xanthohumol C in free and complexed form did not significantly differ, suggesting the release of Xanthohumol C from 2-hydroxypropyl-β-cyclodextrin. Finally, a small-scaled in vivo experiment in a rat model showed that after i. p. administration of the complex, Xanthohumol C can be detected in serum, the brain, and the cerebrospinal fluid at 1 and 6 h post-administration. Mean (± SD) Xanthohumol C serum concentrations after 1, 6, and 12 h were determined as 463.5 (± 120.9), 61.9 (± 13.4), and 9.3 (± 0.8) ng/mL upon i. v., and 294.3 (± 22.4), 45.5 (± 0.7), and 13 (± 1.0) ng/mL after i. p. application, respectively. Accordingly, the formulation of Xanthohumol C/2-hydroxypropyl-β-cyclodextrin is suitable for further in vivo experiments and further pharmaceutical research aiming for the determination of its neuroregenerative potential in animal disease models.

scholarly journals Unravelling the Miscibility of Poly(2-oxazoline)s: A Novel Polymer Class for the Formulation of Amorphous Solid Dispersions

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3587
Author(s):  
Melissa Everaerts ◽  
Ali Tigrine ◽  
Victor R. de la Rosa ◽  
Richard Hoogenboom ◽  
Peter Adriaensens ◽  
...  
Keyword(s):  
Body Temperature ◽  
Drug Release ◽  
Solid Dispersions ◽  
Amorphous Solid ◽  
Water Soluble ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Amorphous Solid Dispersions ◽  
Soluble Polymer ◽  
Water Soluble Polymer

Water-soluble polymers are still the most popular carrier for the preparation of amorphous solid dispersions (ASDs). The advantage of this type of carrier is the fast drug release upon dissolution of the water-soluble polymer and thus the initial high degree of supersaturation of the poorly soluble drug. Nevertheless, the risk for precipitation due to fast drug release is a phenomenon that is frequently observed. In this work, we present an alternative carrier system for ASDs where a water-soluble and water-insoluble carrier are combined to delay the drug release and thus prevent this onset of precipitation. Poly(2-alkyl-2-oxazoline)s were selected as a polymer platform since the solution properties of this polymer class depend on the length of the alkyl sidechain. Poly(2-ethyl-2-oxazoline) (PEtOx) behaves as a water-soluble polymer at body temperature, while poly(2-n-propyl-2-oxazoline) (PPrOx) and poly(2-sec-butyl-2-oxazoline) (PsecBuOx) are insoluble at body temperature. Since little was known about the polymer’s miscibility behaviour and especially on how the presence of a poorly-water soluble drug impacted their miscibility, a preformulation study was performed. Formulations were investigated with X-ray powder diffraction, differential scanning calorimetry (DSC) and solid-state nuclear magnetic resonance spectroscopy. PEtOx/PPrOx appeared to form an immiscible blend based on DSC and this was even more pronounced after heating. The six drugs that were tested in this work did not show any preference for one of the two phases. PEtOx/PsecBuOx on the other hand appeared to be miscible forming a homogeneous blend between the two polymers and the drugs.

Synthesis and Properties of a Thermo-/Light-Sensitive Hydrogel

2012 ◽  
Vol 557-559 ◽  
pp. 1556-1562
Author(s):  
Li Xia Li ◽  
Xiao Dong Xing ◽  
Zu Liang Liu ◽  
Hai Tao Fan ◽  
Man Hu
Keyword(s):  
Uv Irradiation ◽  
Water Soluble ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Copolymer Hydrogel

A newly developed water-soluble azobenzene-containing monomer, 4-(4-((4- ethoxyphenyl)diazenyl)phenoxy)-N-(2-(methacryloyloxy)ethyl)-N,N-dimethylbutan-1-aminium bromide (assigned to M), was synthesized, and then a thermo-/light-sensitive gel was prepared by copolymerization of M and N-isopropylacrylamide. The properties of the gel were subsequently investigated by DSC, UV-vis, and gravimetry. The results showed that the copolymer hydrogel had a very quickly tran-cis photoisomerization rate upon UV irradiation. The critical solution temperature (CST) of the copolymer hydrogel could be toned by the M content and U, did also of the swelling ability.

Rendering Rayon Fibres Antimicrobial and Thermal-Responsive via Layer-by-Layer Self-Assembly of Functional Polymers

2011 ◽  
Vol 236-238 ◽  
pp. 1103-1106 ◽  
Author(s):  
Yuan Feng Pan ◽  
Hui Ning Xiao
Keyword(s):  
Self Assembly ◽  
Guanidine Hydrochloride ◽  
Antimicrobial Property ◽  
Water Soluble ◽  
Solution Temperature ◽  
Poly Vinyl Alcohol ◽  
Layer By Layer ◽  
Anionic Polymer ◽  
Water Soluble Polymer ◽  
Lbl Assembly

A thermal-responsive polymer was prepared by partially acetalyzing poly(vinyl alcohol) (PVA). The completely reversible polymer aggregation and dissolution occur above and below a low critical solution temperature (LCST) for the aqueous solution of the modified PVA. The partially acetalized PVA (APVA) with higher molecular weight and higher degree of acetalysis exhibited a lower LCST transition and was used as an anionic polymer for polymer complexation. Water-soluble polymer, cationic polyhexamethylene guanidine hydrochloride (CPHGH) with antimicrobial property, was also prepared. In conjunction with APVA, CPHGH created the unique antimicrobial polymer multilayers on the surfaces of rayon fibres via layer by layer (LbL) assembly. AFM images revealed that the particles generated by multilayers became larger after the material was treated at 60°C; while the roughness of the surfaces was increased as the layer number increased and then decreased. Moreover, antimicrobial tests also demonstrated that the rayon fiber assembled with (CPHGH/APVA) multilayers exhibited higher antimicrobial activity against E. coli and s. aureus.

Substituent Effects on a Photo-Induced Alternation of the Lower Critical Solution Temperatures of Poly(N-isopropylacrylamide) with Azobenzene Units

2001 ◽  
Vol 710 ◽  
Author(s):  
Haruhisa Akiyama ◽  
Nobuyuki Tamaoki
Keyword(s):  
Free Radical ◽  
Visible Light ◽  
Lower Critical Solution Temperature ◽  
Water Solubility ◽  
Substituent Effects ◽  
Ultra Violet ◽  
Wettability Alteration ◽  
Solution Temperature ◽  
Critical Solution Temperature ◽  
Soluble Polymers

ABSTRACTWe synthesized copolymers of N-isopropylacrylamide (NIPAM) and azobenzene-containing acrylates or acrylamides by free radical polymerization, and investigated the water solubility of these polymers upon irradiation with ultra-violet and visible light. The solubility depended on concentration and structure of photoreactive azobenzene unit in the polymers. The soluble polymers showed the lower critical solution temperature, which was varied along with light irradiation. Photo-induced large wettability alteration was observed in the film.

scholarly journals Ag(I) Catalyzed Grafting of Acrylonitrile onto Gum Arabic by Ce(IV) in Medium: A Kinetic Study

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Geeta Thota ◽  
P. Srinivas
Keyword(s):  
Electron Microscopy ◽  
Gum Arabic ◽  
Probable Mechanism ◽  
Water Soluble ◽  
Graft Polymer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Water Soluble Polymer ◽  
X Ray ◽  
Scanning Electron

Grafting of Acrylonitrile (AN) onto water-soluble polymer Gum arabic (GA) was carried out using ceric ammonium sulfate [Ce(IV)] as initiator in the presence and absence of Ag(I) in H2SO4 medium at 313 K. The rate of oxidation (), rate of grafting (), and grafting efficiency (GE) were determined for catalyzed and uncatalyzed grafting and suitable mechanism was proposed to explain the observed results. No homopolymerization in the absence of GA indicates that the polymer obtained is purely a graft copolymer. A probable mechanism involving the formation of Ag(I)-GA adduct followed by its oxidation with Ce(IV) to give Ag(II)-GA adduct, and its decomposition to give initiating radicals is proposed to explain the observed results. The graft polymer was characterized using Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction, and scanning electron microscopy (SEM) considering GA as reference.

scholarly journals PREPARATION AND IN VITRO EVALUATION OF FAST RELEASE DIAZEPAM SUPPOSITORIES FOR FEBRILE SEIZURES

2017 ◽  
Vol 10 (9) ◽  
pp. 365
Author(s):  
Aseel Alsamman ◽  
Mohammad Othman
Keyword(s):  
Tween 80 ◽  
Febrile Seizures ◽  
Water Soluble ◽  
Infrared Spectrometry ◽  
Ionic Surfactant ◽  
Scanning Calorimetry ◽  
Water Soluble Polymer ◽  
In Vitro Drug Release ◽  
Fast Release

  Objective: The objective of this study was to optimize the best formula for fast release suppositories of diazepam.Methods: Suppositories were prepared by fusion method using Witepsol H15 as oleaginous base, polyethylene glycol as a water-soluble polymer, and Poloxamer 188 as water miscible base. All suppositories were evaluated for physical characteristics, in vitro drug release and kinetic models. The effects of incorporating Tween 80 as a non-ionic surfactant, propylene glycol as a cosolvent, and effervescent pair on the release rate of diazepam from suppositories were investigated. Differential scanning calorimetry and Fourier transform infrared spectrometry were used to characterize physical mixtures of diazepam and the different used bases.Results: Many formulations of diazepam have been prepared and in vitro evaluated. PEG suppositories released diazepam more efficiently than poloxamer and witepsol suppositories. The including of an effervescent pair in the formulation of suppositories greatly enhanced the release of diazepam. The addition of tween 80 to witepsol suppositories, PG to poloxamer suppositories, increased the rate and extent of diazepam release.Conclusion: Fast release of diazepam has been obtained from suppositories containing the effervescent pair (formula F3), which also have good physical properties.

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