Papers by Keyword: Ring-Opening Polymerization

Abstract: A green and nontoxic ring-opening polymerization (ROP) of ε-caprolactone (CL) with appreciably high molecular weight (M_n), low dispersity (PDI), and high conversion was achieved using FeCl₃ as a catalyst and Benzyl alcohol as an initiator in solvents at ambient temperature. Effects of Fe compounds, solvents, reaction temperature, catalyst concentration, and monomer concentration were investigated. The kinetic experiments reveal the controlled nature of using FeCl₃ as a catalyst.

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: After a successfully identified and synthesized Polydimethylsiloxane is known as silicone oil, the product needs to be upgraded and reformulated into a scalable dosage form. The scale-up in the production of silicone oil is very important in order to prepare the fabrication of silicone oil in large quantities. Here, we reported the synthesis of silicone oil using a duplicated scale to produce silicone oil of the same target quality as a laboratory scale. The dosage was increased twice compared to the previous report. The scale-up of silicone oil samples with viscosity values ​​of 1700 - 2920 mPa.s has been successfully synthesized from Octamethylcyclotetrasiloxane (D4) as monomer and Hexamethyldisiloxane (MM) as terminator using ring-opening polymerization method. From FTIR spectroscopy, it was found that all the samples synthesized with double dosage had a structure and functional groups similar to commercial PDMS. From the refractometer and surfgauge measurements, the scale-up sample has a refractive index in between 1.4026 and 1.4038 and a surface tension value from 19.0 to 20.0 m.N/m.

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: Nanoporous carbon was successfully prepared by using polybenzoxazine synthesized from bisphenol-A, melamine and formaldehyde as a precursor. The varied HCl amounts have been added into the pre-polymer solution as a catalyst for the ring-opening polymerization. The reaction was traced by FTIR and DSC. In addition, the degradation behavior was studied by TGA and the textural properties were characterized by SEM and surface area analysis (AS1-MP). The nanoporous carbon obtained showed the highest char yield up to 48%. The interconnected structure from the SEM images of the nanoporous carbon exhibited significantly high surface area of 632 m²/g, high total pore volume up to 1.78 cm²/g, small average pore diameter and narrow pore size distribution detected by AS1-MP. After the activation process, the surface area has been drastically improved leading to the increasing of surface area and total pore volume up to 1119 m²/g and 1.93 cm²/g, respectively. In order to further study on the enhancement of surface area, NaCl, a water soluble compound, has been used as a template. As a result, the surface area has been improved up to 1516 m²/g.

Abstract: Multiwalled carbon nanotubes (MWCNT)-reinforced polymerized cyclic butylene terephthalate (pCBT) nanocomposites were prepared by in situ ring opening polymerization of cyclic butylene terephthalate oligomers (CBT). The results of differential scanning calorimetry (DSC) indicated that the melting peak located at the low temperature (Tm1) increased and that at higher temperature (Tm2) decreased with the increasing of content of the MWCNT. During the cooling the MWCNT served as nucleation points from where crystallization can start. The more the MWCNT in the system the earlier the crystallization starts. The Morphological investigations performed by scanning electron microscopy (SEM) shown that the MWCNT were embedded in the matrix and held tightly by the matrix. The modulus and strength increased with MWCNT concentration in the nanocomposites, however, the elongation at break, absorbed energy at break and impact strength were decreased with the increasing of MWCNT content.

Abstract: In this paper, salen (Al) complex catalytic system was synthesized and used in the polymerization of lactide. The salen (Al) complex catalytic system was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and the ratio of lactide/Al³⁺ on the synthesis of polylactide were also described in the investigation. The results showed that the complex catalytic system could be successfully applied in the ring opening polymerization. The optimum condition of the ring opening polymerization of lactide, which included lactide/Al³⁺ (mol/mol) ratio of 300, reaction temperature of 140 °C, and reaction time of 12 hours.

Abstract: In this investigation, Schiff bases aluminum complex was synthesized and used as the initiator in the polymerization of D,L-lactide. The aluminum complex was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and the ratio of D, L-lactide/Al³⁺ on the synthesis of polylactide were described. The results showed that Schiff bases aluminum complex could be successfully applied in the ring opening polymerization. The optimum condition of the ring opening polymerization of D,L-lactide, which included D,L-lactide/Al³⁺ (mol/mol) ratio of 250, reaction temperature of 120 °C, and reaction time of 16 hours.

Abstract: Preparation of cyclic aryl ketone oligomers containing the iso-phthaloyl moiety by Friedel-Crafts acylation reaction is described. These cyclic oligomers are characterized by a combination of MALDI-TOF-MS and NMR analyses. The cyclic aryl ketone oligomers readily undergo anionic ring-opening polymerization in the melt by using potassium 4, 4-biphenoxide as the initiator, affording linear, high molecular weight poly (ether ketone) s with excellent thermal stability.