Current conduction in Schottky barrier diodes with poly(propylene glycol)-b-polystyrene block copolymer interfacial layer

Polymeric materials have gained great importance in electron devices. There has been considerable number of studies on block copolymers due to enhanced features that appear after co-polymerization. In this study, poly (propylene glycol)-b-polystyrene block copolymer has been synthesized and Schottky barrier diodes (SBDs) have been fabricated with this block copolymer. Current-voltage (I-V) measurements have been conducted at room temperature in order to investigate electrical characteristics and current conductions governing in these SBDs. Series resistance and shunt resistance of the SBDs have been calculated using Ohm’s law. Ideality factor, reverse saturation current and zero-bias barrier height of the SBDs have been extracted from the forward-bias I-V data. Fabricated SBDs exhibited high rectifying ratio of the order 104. Also, current conduction mechanisms and the density of interface states in the SBDs have been investigated. Calculated values of density of interface states in the SBDs are on the order of 1013 which is acceptable for this kind of SBDs having polymeric interfacial layer

Synthesis and characterization of poly(linoleic-g-epsilon-caprolactone) graft copolymers via click reaction and ring-opening polymerization

Linoleic acid modified with auto-oxidation, hydroxylation, bromination and azidation was used to synthesis graft copolymers using omega-alkyne-terminated poly(epsilon-caprolactone) (alk-PCLs) via click reaction. In the first step, the polymeric linoleic acid (PLina) as macroinitiator was obtained by the autoxidation of linoleic acid. Hydroxylation of the PLina was then carried out using diethanolamine to produce hydroxylated polymeric linoleic acid (PLina-OH). The PLina-OH was chemically modified with 2-bromopropionyl bromide to obtain bromo-functionalized polymeric linoleic acid (PLina-Br). This macroinitiator was then modified with sodium azide, resulting in azide polymeric linoleic acid (PLina-N-3). In a parallel process, omega-alkyne-terminated poly(epsilon-caprolactone) (alk-PCLs) were prepared via ROP of the epsilon-caprolactone monomer in the presence of propiolic acid, 3-butyn-1-ol, 5-hexynoic acid, and propargyl alcohol as the precursors and tin(II) 2-ethyl hexanoate (Sn(Oct)(2)) as the catalyst. These preliminary steps involved the synthesis of azide and alkyne compounds capable of being linked together via the alkyne-azide cycloaddition reaction catalyzed by copper (Cu(I)), which led to poly(linoleic acid)-g-poly(epsilon-caprolactone) (PLina-g-PCL). The obtained polymers were characterized by proton nuclear magnetic resonance (H-1 NMR), Fourier-transform infrared (FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and elemental analysis.Duzce University Research FundDuzce University [2016.07.06.487, 2019.07.06.1021]This study was funded by the Duzce University Research Fund (Grant Number: 2016.07.06.487, 2019.07.06.1021).WOS:0006914680000012-s2.0-8511054964

One-pot PolimerleşmeYöntemiyle Poli(linoleik asit)-g-Poli(N-isopropilakrilamit)-g-Poli(D,L-laktid) Graft Kopolimerlerin Sentezi ve Karakterizasyonu

Bu çalışmada, Otookside polimerik linoleik asit peroksit (PLina)’nın halka açılma polimerizasyonu ve serbest radikal polimerizasyonu bir arada kullanılarak tek adımda (one-pot) üç bloklu graft kopolimerler sentezlendi. Poli(linoleik asit)-g-poli(N-isopropilakrilamit)-g-poli(D,L-laktid) yapısına sahip graft kopolimerler; PLina’nın ana zincirinde bulunan peroksit grupları ile N-isopropilakrilamit (NIPAM) monomeriyle serbest radikal polimerizasyonu ve PLina’nın karboksilik asit grupları ile D,L-laktid (LA) monomeri arasındaki halka açılma polimerizasyonunun bir arada (one-pot) kullanılmasıyla sentezlendiler. One-pot polimerizasyon reaksiyonuna etki eden polimerizasyon süresi, başlatıcı konsantrasyonu ve monomer konsantrasyonu gibi temel parametreler incelendi. Elde edilen graft kopolimerlerin karakterizasyonları 1H NMR ve GPC teknikleri kullanılarak yapıldı

Synthesis and characterization of star-shaped block copolymers composed of poly(3-hydroxy octanoate) and styrene via RAFT polymerization

This study investigated a macro reversible addition fraction chain transfer (RAFT) agent based on three-arm hydroxylated star-shaped poly(3-hydroxy octanoate). The utilization of this star-shaped poly(3-hydroxy octanoate) macro-RAFT agent in the RAFT process resulted in efficient control in the preparation of star-shaped block styrene copolymers. Poly(3-hydroxy octanoate) (PHO) was reacted with diethanol amine (DEA) in order to obtain three-arm hydroxylated poly(3-hydroxy octanoate) (PHO-DEA). A carboxylic acid-functionalized RAFT agent (2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid) was reacted with the PHO-DEA in order to obtain a star-shaped PHO macro-RAFT agent (PHO-R2). A series of AB3 type PHO-polystyrene (PHO-PS) star-shaped block copolymers were obtained via the polymerization of styrene (S) using the PHO-R2 in toluene at 80 °C. The RAFT polymerization was seen to obey the polymerization kinetics of controlled free radical polymerization. The plasticizing effect of the PHO soft segments was influenced by the glass transition temperature (Tg) of polystyrene. This was clearly observed in the block copolymers. Moreover, it was clear that this plasticizing effect disappeared in the block copolymers as a result of the increase in polymerization time. The molar masses of the obtained copolymers increased in parallel with increases in the polymerization time. Structural, physiochemical, and thermal characterization of the obtained products was carried out using size-exclusion chromatography (SEC), proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) techniques. The polymerization kinetics of the star-shaped block copolymers were also investigated in detail

Halka Açılma Polimerizasyonuyla Poli(linoleik asit)-g-Poli(ε-kaprolakton) ve Poli(linolenik asit)-g-Poli(ε-kaprolakton) Graft Kopolimerlerin Sentezi ve Karakterizasyonu

Bu çalışmada, linoleik asit (Lina) ve linolenik asit (Linl)’ler otooksidasyona uğratılarak polimerik linoleik asit peroksit (PLina) ve polimerik linolenik asit peroksit (PLinl) elde edildi. Lina ve Linl’lerin otooksidasyonu hava ortamında oda sıcaklığında gerçekleştirilerek % 1.10-1.20 peroksit içeren, % 98 çözünür kısımlarına sahip yapıları elde edildi. Biyobozunur poli(linoleik asit)-g-poli(ε-kaprolakton) ve poli(linolenik asit)-g-poli(ε-kaprolakton) graft kopolimerler, otookside olmuş linoleik asit ve linolenik asit’lerin karboksilik asit grupları ile  ε-kaprolakton monomeri arasındaki halka açılma polimerizasyonuyla elde edildiler. Poli(linoleik asit)-g-poli(ε-kaprolakton) ve poli(linolenik asit)-g-poli(ε-kaprolakton) graft kopolimerlerin instristik viskozite değerleri belirlendi. Elde edilen graft kopolimerlerin karakterizasyonları 1H NMR, FT-IR,  TGA, DSC ve GPC teknikleri kullanılarak yapıldı

Biodegradable Poly(epsilon-Caprolactone)-Based Graft Copolymers Via Poly(Linoleic Acid): In Vitro Enzymatic Evaluation

WOS: 000350563400016Well-defined graft copolymers based on poly(epsilon-caprolactone) (PCL) via poly(linoleic acid) (PLina), are derived from soybean oil. Poly(linoleic acid)-g-poly(epsilon-caprolactone) (PLina-g-PCL) and poly(linoleic acid)-g-poly(styrene)-g-poly(epsilon-caprolactone) (PLina-g-PSt-g-PCL) were synthesized by ring-opening polymerization of epsilon-caprolactone initiated by PLina and one-pot synthesis of graft copolymers, and by ring-opening polymerization and free radical polymerization by using PLina, respectively. PLina-g-PCL, PLina-g-PSt-g-PCL3, and PLina-g-PSt-g-PCL4 copolymers containing 96.97, 75.04 and 80.34 mol% CL, respectively, have been investigated regarding their enzymatic degradation properties in the presence of Pseudomonas lipase. In terms of weight loss, after 1 month, 51.5 % of PLina-g-PCL, 18.8 % of PLina-g-PSt-g-PCL3, and 38.4 % of PLina-g-PSt-g-PCL4 were degraded, leaving remaining copolymers with molecular weights of 16,140, 83,220 and 70,600 Da, respectively. Introducing the PLina unit into the copolymers greatly decreased the degradation rate. The molar ratio of [CL]/[Lina] dramatically decreased, from 21.3 to 8.4, after 30 days of incubation. Moreover, reduced PCL content in PLina-g-PSt-g-PCL copolymers decreased the degradation rate, probably due to the PSt enrichment within the structure, which blocks lipase contact with PCL units. Thus, copolymerization of PCL with PLina and PSt units leads to a controllable degradation profile, which encourages the use of these polymers as promising biomaterials for tissue engineering applications.Turkish Scientific Research CouncilTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [110T884, 211T016]; Bulent Ecevit University Research FundBulent Ecevit University [2012-17-21-03]This work was supported financially by the Turkish Scientific Research Council (Grants Numbers: 110T884, 211T016) and Bulent Ecevit University Research Fund (Grant Number: 2012-17-21-03)

Comparison of Electronic Parameters of Low Voltage Organic Field-Effect Transistors with Novel Gel Gate Insulators

WOS: 000469369800012In this paper, regioregular poly(3-hexylthiophene-2,5-diyl) (rr-P3HT)-based low voltage organic field-effect transistors (OFETs) with three kinds of non-ionic gel gate insulators (NIGIs) were fabricated and compared in terms of their electronic properties. One of the NIGI was prepared by mixing solution-processed poly(methyl acrylate) (PMA) with propylene carbonate (PC) until it becoming a gel state and same procedure was applied to the solution-processed copolymers of PMA called as P18 and P28. As a result, it was seen that fabricated OFETs could be operated at low voltages which is very significant property in order to manipulate the devices in low power electronic applications. On the other hand, it was noted that mobilities of the transistors were enhanced by reducing the effective capacitance (EC) of the NIGIs. This could be attributed to less charge carrier self-localization formation between the insulator-semiconductor interface when the EC was decreased. Furthermore, devices showed similar on-to-off current (I-ON/I-OFF) ratio which was good for using them in inverter applications. Besides, subthreshold swing (SS) for the P18 non-ionic gel OFET (NIGOFET) was the highest probably due to the less water-repellent chemical structure of the P18 NIGI.Duzce University Scientific Research Projects unitDuzce University [2017.07.02.621, 2015.05.03.381]This study was presented in the 5th International Conference on Materials Science and Nanotechnology For Next Generation (MSNG2018) which held between 4-6 October 2018 in Cappadocia Turkey. Furthermore, we appreciate the Duzce University Scientific Research Projects unit for providing us financial support under the Grant [2017.07.02.621] and [2015.05.03.381]