Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    “On–Off” Thermocontrol of Solute Transport. I. Temperature Dependence of Swelling of N-Isopropylacrylamide Networks Modified with Hydrophobic Components in Water (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 531-537 
    Details
    ISSN: 1573-904X
    Keywords: thermosensitivity ; hydrogels ; N-isopropylacrylamide ; interpenetrating polymer networks ; surface deswelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The swelling in water, as a function of temperature, of two series of N-isopropylacrylamide (NIPA Am) polymer networks was studied. In the first series, n-butylmethacrylate (BMA) was copolymerized with NIPA Am, and in the second, polytetramethylene ether glycol (PTMEG) was incorporated into NIPAAm network as a chemically independent interpenetrating network. With increasing BMA content in the poly(NIPAAm-co-BMA) network, the gel collapse point was lowered and the gels deswelled in a more gradual manner with increasing temperature. In the interpenetrating polymer networks (IPN) system, the gel collapse point was not significantly changed by the amount of incorporated PTMEG. In DSC thermograms of swollen samples, the shape and onset temperature of the endothermic peak corresponded to the gel deswelling behavior and gel collapse point. The temperature dependence of equilibrium swelling in water was shown to be a function of the gel composition in both network series. The synthesized networks formed a dense surface layer as the temperature increased past the gel collapse point. This dense layer retarded water efflux and thereby resulted in water pockets at the membrane surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015871732706
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    “On–Off“ Thermocontrol of Solute Transport. II. Solute Release from Thermosensitive Hydrogels (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 624-628 
    Details
    ISSN: 1573-904X
    Keywords: thermocontrol ; on–off release ; thermosensitive hydrogels ; interpenetrating polymer networks ; N-isopropylacrylamide ; polytetramethylene ether glycol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Poly(N-isopropylacrylamide) (NIPAAm)/polytetramethylene ether glycol (PTMEG) interpenetrating polymer networks (IPNs) were synthesized and their feasibility as thermosensitive hydrogels for drug release was investigated. The release of indomethacin incorporated into these matrices showed pulsatile patterns in response to temperature changes and was sensitive to a few degrees of temperature fluctuation. The temperature inducing on–off release deviated from the gel collapse temperature of unloaded gel, possibly because of solute effects on network properties. The lag time and release profile of indomethacin in the low-temperature region (on process) of each temperature cycle were affected by the gel composition and applied temperature. The results of this study demonstrate that solute release can be regulated by rapid deswelling of the surface of the gels in response to temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015860824953
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Effect of the incorporation of amino groups in a glucose-responsive polymer complex having phenylboronic acid moieties (1991)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 261-264 
    Details
    ISSN: 1042-7147
    Keywords: Polymer complex ; diabetes ; phenylboronic acid ; stimuli-responsive polymer drug delivery system ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A novel polymer complex system sensitive to glucose was studied as a candidate material for formulating a chemically regulated insulin release system. A ternary copolymer of N-vinyl-2-pyrrolidone (NVP), 3-acrylamidophenylboronic acid (AAm-PBA) and N,N-dimethylaminopropylacrylamide (DMAPAA) (poly(NVP-co-PBA-co-DMAPAA)) was synthesized by radical copolymerization. The phenylboronic acid group in this copolymer serves as a glucose sensor moiety. Poly(NVP-co-PBA-co-DMAPAA) was soluble in water in the pH range of 3-12, in sharp contrast to a binary copolymer of NVP and AAm-PBA (poly(NVP-co-PBA)) which showed solubility only under alkaline aqueous conditions, where the boronic acid group is in a tetrahedral ionized form. The protonated amino group in poly(NVP-co-PBA-DMAPAA) contributed to increase the solubility of the polymer under physiological and acidic aqueous conditions. Furthermore, poly(NVP-co-PBA-co-DMAPAA) formed a stable polymer complex gel with poly(vinyl alcohol) (PVA) in pH 7.4 phosphate buffered solution due to the formation of a covalent linkage between the boronic acid groups in ternary copolymer and diol units in PVA. The release of myoglobin as model protein from the complex gel was increased immediately after the addition of glucose, due to the transition of gel into sol state, indicating the feasibility of this complex gel as a candidate material for a glucose-responsive delivery system for insulin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1991.220020508
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...