Photoresponsive Polymers. Reversible Solution Viscosity Change of Poly(methyl methacrylate) Having Spirobenzopyran Side Groups

Masahiro Irie; Akira Menju; Koichiro Hayashi

doi:10.1021/ma60072a032

PROTON MAGNETIC RESONANCE LINE WIDTH AS A FUNCTION OF POLYMER TACTICITY

Canadian Journal of Chemistry ◽

10.1139/v66-025 ◽

1966 ◽

Vol 44 (2) ◽

pp. 153-156 ◽

Cited By ~ 9

Author(s):

S. Brownstein ◽

D. M. Wiles

Keyword(s):

Magnetic Resonance ◽

Methyl Methacrylate ◽

Proton Magnetic Resonance ◽

Chloroform Solution ◽

Spin Coupling ◽

Solution Viscosity ◽

Dilute Solution ◽

Poly Methyl Methacrylate ◽

Resonance Line Width ◽

Polymer Tacticity

The high resolution proton magnetic resonance spectra of five samples of poly(methyl methacrylate) in chloroform solution have been measured with 100 Mc/s equipment. The widths of the absorption lines arising from the protons of the α-methyl and the methoxyl groups have been compared. The widths are greater when the polymer is predominantly syndiotactic than when it is predominantly isotactic. It is concluded that isotactic samples have the more extended conformation in chloroform solution. An analogy with dilute solution viscosity measurements is outlined in support of this conclusion. Differences between the widths of the lines of the methylene protons in a completely isotactic poly(methyl methacrylate) sample are attributed to long range spin coupling.

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Processing parameters for electrospinning poly(methyl methacrylate) (PMMA)/titanium isopropoxide composite in a pump-free setup

AAS Open Research ◽

10.12688/aasopenres.12909.1 ◽

2018 ◽

Vol 1 ◽

pp. 27

Author(s):

Leah Nyangasi ◽

Dickson Andala ◽

Charles Onindo ◽

Alphonse Wanyonyi ◽

Josphine Chepngetich

Keyword(s):

Methyl Methacrylate ◽

Polymer Solution ◽

Solution Concentration ◽

Titanium Isopropoxide ◽

Processing Parameters ◽

Solution Viscosity ◽

Poly Methyl Methacrylate ◽

Size And Morphology ◽

Set Up ◽

Almost All

Background: Electrospinning is a technique for producing nanofibers, useful in many fields of nanotechnology. The size and morphology of the nanofibers obtained depends on the polymer solution properties, the parameters of the equipment and the conditions of the surrounding. In almost all reported electrospinning set ups, a pump ,which regulates the flow of the polymer solution, has been included as one of the requirements. In this study, the effects of solution concentration, viscosity, voltage and the distance from the tip of the syringe to the aluminum collector on the morphology and diameters of poly(methyl methacrylate)(PMMA) fibers were investigated, using a pump-free electrospinning set up. Methods: Varied PMMA concentration (50 -120 mg/mL), voltage (10-18 kV) and distance (5 – 18 cm) of electrospinning were studied and the optimum electrospinning conditions identified. PMMA/ titanium isopropoxide solution of ratio 1:2 was prepared, electrospun at optimized conditions (15 kV, 18 cm, Dichloromethane/Dimethylformamide 60:40) and the fibers obtained analyzed using a scanning electron microscope. Results: Solutions of PMMA whose concentrations were less than 50 mg/mL, produced beads on fibers, whereas those at ~ 100 mg/mL formed the best bead-free fibers of diameter 350±50 nm. The results showed a direct dependence of fiber diameter on the solution viscosity. Fibers of larger diameters were obtained when the distance from the tip of the syringe to the aluminum collector and voltage were increased but at higher distances (>18 kV) fewer fibers were collected. When the voltage was steadily increased, the fibers broadened and the diameters were non-uniform due to splaying and splitting. Increasing the distance between the pipette-tip and the collector from 10 to 18 cm resulted in reduced electric field which in turn yielded fewer fibers. Conclusions: The results obtained in a pump free set-up were comparable to those eletrospun in the presence of a pump.

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Electrospinning of poly(methyl methacrylate) nanofibers in a pump-free process

Journal of Polymer Engineering ◽

10.1515/polyeng-2012-0096 ◽

2013 ◽

Vol 33 (5) ◽

pp. 453-461 ◽

Cited By ~ 7

Author(s):

Jasbir S. Bedi ◽

Daniel W. Lester ◽

Yuan X. Fang ◽

John F.C. Turner ◽

John Zhou ◽

...

Keyword(s):

Methyl Methacrylate ◽

Fiber Diameter ◽

Solution Concentration ◽

Prolate Spheroid ◽

Nozzle Diameter ◽

Solution Viscosity ◽

Diameter Distribution ◽

Poly Methyl Methacrylate ◽

Voltage Bias ◽

Free Process

Abstract The effects of processing parameters, including solution concentration, viscosity, nozzle diameter, voltage bias and the nozzle to collector distance, on the morphology and diameters of poly(methyl methacrylate) (PMMA) fibers have been systematically investigated, using a unique pump-free electrospinning method. For PMMA solution concentrations less than the critical entanglement concentration, ce, prolate spheroid-shaped droplets or beads with fibers were formed, whereas at concentrations above ce, good quality bead-free fibers were formed. Quantitative analysis revealed a linear dependence between the solution viscosity and fiber diameter. Larger fiber diameters were achieved by increasing the nozzle diameter and voltage bias. Increasing the bias voltage has the additional effect of broadening the diameter distribution, as a result of splaying and splitting. By contrast, when the strength of the electrical field was reduced by increasing the distance between the nozzle and collector, the overall fiber diameter was reduced.

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