Recently, responsive surfaces have attracted attention due to their potential applications.
Repor... more Recently, responsive surfaces have attracted attention due to their potential applications. Reported research have studied the deposition of environmentally responsive particles on different surfaces, qualitatively tested their response to environmental conditions and studied their possible applications. In this work, novel fluorescent temperature-sensitive nanoparticles were synthesized using a surfactant free emulsion polymerization technique: poly(N-isopropylacrylamide-co-5% vinyl cinnamate) (p(NIPAM)5%VC). The new particles were characterized using dynamic light scattering and fluorescence spectroscopy. A novel sensitive method for the quantitative analysis of p(NIPAM) 5% VC using fluorescence spectroscopy was developed to determine the concentration of nanoparticle dispersions. This was further used to quantitatively determine the mass of nanoparticles deposited per unit area of glass pre-treated with acid, glass pre-treated with base, quartz, stainless steel, gold and teflon at 25°C and 60°C. Factors affecting the adsorption/desorption of the nanoparticles were studied, including the effect of substrate surface charge, surface roughness (using atomic force microscopy, AFM), hydrophilicity/hydrophobicity and the temperature at which the adsorption/desorption experiments were carried out. The results show that the effect of surface charge is the most significant, followed by that of surface roughness and temperature. Meanwhile, the influence of the hydrophobicity/hydrophilicity of the surface on the adsorption/desorption of nanoparticles appears to be far less significant than the previously mentioned factors.
This work aims to study the behavior of temperature-responsive p(NIPAM) and temperature/pH-respon... more This work aims to study the behavior of temperature-responsive p(NIPAM) and temperature/pH-responsive p(NIPAM)/acrylic acid (AA) microgels. Three microgels were synthesized using surfactant freeemulsion polymerization technique, these are p(NIPAM), p(NIPAM)-co-AA 95:5% (w/w) and p(NIPAM)-co-AA 90:10% (w/w). Dynamic light scattering was used to study the behavior of diluted microgeldispersions (0.5%, w/w p(NIPAM)), while rheology was used to study the viscosity of 2% (w/w) p(NIPAM)dispersions. The characterization data indicate the swelling/deswelling and flocculation/deflocculationbehavior of the microgels. The conditions required for flocculation were used to test the ability of themicrogel dispersions to block a membrane of pore size 5 m. In 3 h, p(NIPAM), p(NIPAM) 5% AA (w/w)and p(NIPAM)10% AA (w/w) blocked the membrane (decrease the flow rate) by 96.16, 59.44 and 59.8%respectively. Thus, the controlled flocculation of microgels may be used in applications where pore block-ing is important such as the treatment of dentinal hypersensitivity, given that the VPTT of p(NIPAM) is≈34◦C, which is very close to the human body temperature.
Recently, responsive surfaces have attracted attention due to their potential applications.
Repor... more Recently, responsive surfaces have attracted attention due to their potential applications. Reported research have studied the deposition of environmentally responsive particles on different surfaces, qualitatively tested their response to environmental conditions and studied their possible applications. In this work, novel fluorescent temperature-sensitive nanoparticles were synthesized using a surfactant free emulsion polymerization technique: poly(N-isopropylacrylamide-co-5% vinyl cinnamate) (p(NIPAM)5%VC). The new particles were characterized using dynamic light scattering and fluorescence spectroscopy. A novel sensitive method for the quantitative analysis of p(NIPAM) 5% VC using fluorescence spectroscopy was developed to determine the concentration of nanoparticle dispersions. This was further used to quantitatively determine the mass of nanoparticles deposited per unit area of glass pre-treated with acid, glass pre-treated with base, quartz, stainless steel, gold and teflon at 25°C and 60°C. Factors affecting the adsorption/desorption of the nanoparticles were studied, including the effect of substrate surface charge, surface roughness (using atomic force microscopy, AFM), hydrophilicity/hydrophobicity and the temperature at which the adsorption/desorption experiments were carried out. The results show that the effect of surface charge is the most significant, followed by that of surface roughness and temperature. Meanwhile, the influence of the hydrophobicity/hydrophilicity of the surface on the adsorption/desorption of nanoparticles appears to be far less significant than the previously mentioned factors.
This work aims to study the behavior of temperature-responsive p(NIPAM) and temperature/pH-respon... more This work aims to study the behavior of temperature-responsive p(NIPAM) and temperature/pH-responsive p(NIPAM)/acrylic acid (AA) microgels. Three microgels were synthesized using surfactant freeemulsion polymerization technique, these are p(NIPAM), p(NIPAM)-co-AA 95:5% (w/w) and p(NIPAM)-co-AA 90:10% (w/w). Dynamic light scattering was used to study the behavior of diluted microgeldispersions (0.5%, w/w p(NIPAM)), while rheology was used to study the viscosity of 2% (w/w) p(NIPAM)dispersions. The characterization data indicate the swelling/deswelling and flocculation/deflocculationbehavior of the microgels. The conditions required for flocculation were used to test the ability of themicrogel dispersions to block a membrane of pore size 5 m. In 3 h, p(NIPAM), p(NIPAM) 5% AA (w/w)and p(NIPAM)10% AA (w/w) blocked the membrane (decrease the flow rate) by 96.16, 59.44 and 59.8%respectively. Thus, the controlled flocculation of microgels may be used in applications where pore block-ing is important such as the treatment of dentinal hypersensitivity, given that the VPTT of p(NIPAM) is≈34◦C, which is very close to the human body temperature.
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Papers by Reham Mohsen
Reported research have studied the deposition of environmentally responsive particles on
different surfaces, qualitatively tested their response to environmental conditions and studied
their possible applications. In this work, novel fluorescent temperature-sensitive
nanoparticles were synthesized using a surfactant free emulsion polymerization technique:
poly(N-isopropylacrylamide-co-5% vinyl cinnamate) (p(NIPAM)5%VC). The new particles
were characterized using dynamic light scattering and fluorescence spectroscopy. A novel
sensitive method for the quantitative analysis of p(NIPAM) 5% VC using fluorescence
spectroscopy was developed to determine the concentration of nanoparticle dispersions. This
was further used to quantitatively determine the mass of nanoparticles deposited per unit area
of glass pre-treated with acid, glass pre-treated with base, quartz, stainless steel, gold and
teflon at 25°C and 60°C. Factors affecting the adsorption/desorption of the nanoparticles
were studied, including the effect of substrate surface charge, surface roughness (using
atomic force microscopy, AFM), hydrophilicity/hydrophobicity and the temperature at which
the adsorption/desorption experiments were carried out. The results show that the effect of
surface charge is the most significant, followed by that of surface roughness and temperature.
Meanwhile, the influence of the hydrophobicity/hydrophilicity of the surface on the
adsorption/desorption of nanoparticles appears to be far less significant than the previously
mentioned factors.
Reported research have studied the deposition of environmentally responsive particles on
different surfaces, qualitatively tested their response to environmental conditions and studied
their possible applications. In this work, novel fluorescent temperature-sensitive
nanoparticles were synthesized using a surfactant free emulsion polymerization technique:
poly(N-isopropylacrylamide-co-5% vinyl cinnamate) (p(NIPAM)5%VC). The new particles
were characterized using dynamic light scattering and fluorescence spectroscopy. A novel
sensitive method for the quantitative analysis of p(NIPAM) 5% VC using fluorescence
spectroscopy was developed to determine the concentration of nanoparticle dispersions. This
was further used to quantitatively determine the mass of nanoparticles deposited per unit area
of glass pre-treated with acid, glass pre-treated with base, quartz, stainless steel, gold and
teflon at 25°C and 60°C. Factors affecting the adsorption/desorption of the nanoparticles
were studied, including the effect of substrate surface charge, surface roughness (using
atomic force microscopy, AFM), hydrophilicity/hydrophobicity and the temperature at which
the adsorption/desorption experiments were carried out. The results show that the effect of
surface charge is the most significant, followed by that of surface roughness and temperature.
Meanwhile, the influence of the hydrophobicity/hydrophilicity of the surface on the
adsorption/desorption of nanoparticles appears to be far less significant than the previously
mentioned factors.