Papers by Keyword: Polydimethylsiloxane

Abstract: The purpose of this study is to evaluate the thermal degradation of hybridize doped poly(dioctylfluorene) (PF8) film with polydimethylsiloxane (PDMS). The hybridized PF8/PDMS films were produced using solvent casting technique. The poly(dioctylfluorene) was dissolved using chloroform and subsequently polydimethylsiloxane was added prior mixing. Three different concentrations of PF8 were used to prepare the doped film. After casting, the samples were put in an oven at 100°C for 5 minutes for curing process. Later the thermal degradation test was conducted on the prepared sample for the duration of 1 hour, 2 hours, 3 hours and 24 hours to observe the effect of temperature on the photoluminescence properties of PF8. UV-visible spectroscopy was mainly used to measure the absorption intensity of the hybridized materials. It was configured that the optimum doped concentration for PF8 with PDMS is by using 5.0×10^-3 mol of PF8. This is due to a good solubility of PF8 and easy to be casted.

Abstract: Polydimethylsiloxane (PDMS) has been widely used as a vitreous humour substitution in vitreoretinal surgery. Due to its limited availability and increasing domestic needs, the price of PDMS in Indonesia became very expensive. Previously, we reported the synthesized of PDMS from a high grade of monomer of 98% of Octamethylcyclotetrasiloxane (D4) and found that all PDMS samples produced high quality samples similar to that of commercial one. However, by considering the ease of obtaining raw materials and also the production costs, the synthesis of PDMS using monomer which easy to be found in Indonesia and low production costs is needed to be developed. Here, we reported the synthesis of PDMS using low grade of 96% of D4 in order to produce high quality of PDMS with low viscosity that can be used for vitreous humous substitution in vitreoretinal surgery. PDMS samples with low viscosity value of 0.94-1.35 Pa.s have been successfully synthesized from low grade of D4 and MM using ring-opening polymerization method. The yields of PDMS resulted in this research were in the range between 67.27% and 76.26%. From FTIR spectroscopy, it is found that all synthesized samples have structure and functional groups similar to PDMS using high grade of monomer of 98% Octamethylcyclotetrasiloxane (D4). From refractometer and surfgauge measurements, all samples have refractive index in the range of 1,4034-1,4040 and the value surface tension was 21 m.N/m.

Abstract: Duration of use and injectability are external factors for Polydimethylsiloxane (PDMS) that needs to be considered when PDMS utilized as a vitreous substituted liquid in vitreoretinal surgery. In general, PDMS which has been used as a substitute for vitreous humour is PDMS with a low viscosity in the value about 1000 cSt and a high viscosity at a value of about 5000 cSt. Various deficiencies have been encountered from low and high viscosity of PDMS, causing research to be continued to obtain PDMS which has suitable properties as a substitute for vitreous humour. One of them is research to obtain medium viscosity of PDMS with a viscosity value of about 2000 cSt. Here, we reported synthesis and characterization of PDMS with medium viscosity in ranges from 1800 to 2600 mPas. PDMS was synthesized through Ring-Opening Polymerization (ROP) pathway using the monomer of Octamethylcyclotetrasiloxane (D4) and the chain terminator of Hexamethyldisiloxane (MM). Various concentrations of potassium hydroxide (KOH) of 3, 4, 6 and 8 %(w/v) were applied as initiator to form gel of PDMS. All synthesized PDMS samples were identified to have viscosity values of 1800-2600 mPas, refractive index values of 1.4042-1.4044 and surface tension values of 22-23 mN/m. Meanwhile, the results of Fourier-Transform Infrared (FTIR) measurement showed that the absorption peaks were similar to that of our previous report.

Abstract: The work presents the investigations of working out the method of obtaining radio-absorbing composite material based on magnetite nanoparticles and polydimethylsiloxanes. The electron microphotographs of nanoparticles were obtained and the radio-physical characteristics of material in the frequency band of 0.1-8 GHz were measured.

Abstract: Polydimethylsiloxane (PDMS) is a tamponade substance that is used as vitreous humour substitutes in vitreoretinal surgery. PDMS can be obtained from monomers of Octamethylcyclotetrasiloxane (D4) that was reacted with Hexamethyldisiloxane through polymerization reactions in a base condition. The monomers are very difficult to obtain in Indonesia, therefore another alternative monomer is needed to produce PDMS with specific properties for vitreoretinal surgery. Here, we reported the synthesis of monomer for replacing D4 through hydrolysis process of Dichlorodimethylsilane (DCMS). Furthermore, the synthesized monomer was used to produce PDMS. The process of DCMS hydrolysis assisted by KOH 0.5 M along 18 hours in reflux system. The synthesized monomer has viscosity of 171 mPas, refractive index of 1.4005 and surface tension of 17 mN/m. PDMS was produced using synthesized monomer by ring-opening polymerization. It is found that the properties of PDMS are very similar with that of commercial PDMS of 5500 cSt.

Abstract: PA6 fibers and fabric properties were studied by adding PDMS, and PA6 / PDMS blend fibers were prepared by melt spinning. The experiment found that the addition of PDMS can significantly promote the rheology of the PET / PDMS blend melt. DSC tests show that the addition of PDMS has basically no effect on its crystallization and melting characteristics. With the increase of PDMS content, the contact angle of water on the blended fabric surface increased. KES-FB was used to evaluate fabrics made from PA6 / PDMS blended fibers. It was found that with the increase of PDMS content, the softness and elasticity of the fabrics were improved, and the stain resistance experiments showed that the modified fabrics had good resistance dirty performance.

Abstract: The purpose of this study is the development of a composite material composed of a main layer of polydimethylsiloxane (PDMS) and a reinforcement of polytetrafluoroethylene (PTFE), to be used later in human prosthesis coatings. A mass ratio of the main layer consisting of PDMS:Tetraethyl orthosilicate (TEOS):Di-n-butyl tin dilaurate (DBTL) in the range of 33:1:0.5; 25:1:0.5; 10:1:0.5, and the mass ratio of the composite material (PTFE:PDMS) with a range was evaluated of 1:9; 1:1; 2:3. Obtaining the following results: Tensile strength of 0.085 MPa based on the ratio of 33:1:0.5 - 1:9 and 0.59 MPa with respect to the ratio of 10:1:0.5 - 2:3, evidencing an increase in tensile strength by decreasing the weight of PDMS and increasing the weight of PTFE. On the other hand, the composite material obtained is hydrophobic, insoluble in ethanol and water, has a cross-linking percentage of 98.74 % and 99.66 % respectively, also has a minimum permeance of 5.24x10^-7 (g Pa^-1 s^-1 m^-2). With which it is concluded that the treatment whose properties resemble the human skin is the combination 10:1:0.5 - 1:1 that allowed to obtain an average tensile strength of 0.66 MPa, average modulus of elasticity of 6.56 MPa, similar to the dermis of a 43 year old person.

Abstract: Polymer composites are gaining attention due to their superior thermal properties. Especially carbon black /carbon nanotubes/ graphene filled polymer composites are used in energy harvesting, thermal actuators and MEMS. The coefficient of thermal expansion (CTE) is one of the most important properties in the polymer composite. In the present study, thermal expansion of polydimethylsiloxane (PDMS) matrix is filled with carbon black particle of varied volume fraction is modeled. Two-dimensional finite element (FE) model is computed in order to explain the thermal expansion behavior of the polymer composite and same is carried out for ambient to 70 K temperature. A 2D regular arrangement of circular particle packing model is set up and simulated. The FE model predicts that filler geometry has a little effect on the thermal expansion than the percentage of filler in the composite. Thermal expansion of composite is compared with the theoretical model. It shows that the CTE of composite reduces as the filler percentage increase, also gives good agreement in the both models. Hence, it is found that the addition of carbon black to the polymer composite could make it perform significantly better in thermal expansion.

Abstract: Polydimethylsiloxane (PDMS) with two type viscosity that commonly used as vitreous humour substitutes in vitreoretinal surgery has been successfully synthesized by ring-opening polymerization. Optimization of synthesized parameters such as ratio of monomer and chain terminator, the amount of initiator, mixing temperature and reaction time was carried out to obtain PDMS materials having similar properties with commercial product. PDMS with viscosity of 1.17 Pas that very close to viscosity of commercial PDMS of 1.08 Pas, was successfully synthesized with a ratio of 26:10 monomer and terminator chain, 0.58 M of initiator KOH, 170 ^oC of mixing temperature and 35 minutes of reaction time. By changing reaction time to 40 minutes, PDMS was successfully synthesized with viscosity of 3.42 that similar to that of commercial one.

Abstract: In this work, we synthesize Hafnium (IV) oxide (HfO₂) ink from hafnium chloride (HfCl₄) powder assisted with deionized water. The poly acrylic acid (PAA) is used as surfactant to decrease the surface tension. Conversion of HfCl₄ into HfO₂ was detected by Raman spectroscopy and energy dispersive X-ray spectroscopy (EDS) characterization techniques. This proposed ink can be easily synthesized at a low temperature. Using the synthesis ink, a liquid capacitor is proposed, which is tested for electrochemical analysis. Indium tin oxide (ITO) coated PET is used as bottom and top current collector electrode, polydimethylsiloxane (PDMS) mold is used as separator, and HfO₂ ink is used as aqueous electrolyte. Liquid capacitor is also tested on different bending diameters using bending machine from flat down to 10 mm bending curvature, which shows a stable capacitor function.