Tung Oil Anhydride Modified Hemp Fiber/Polypropylene Composites: The Improved Toughness, Thermal Stability and Rheological Property

Hongming Wu,Dinghong Xu,Ying Zhou,Chengtao Gao,Jianbing Guo,Weidi He,Yong He,Shuhao Qin 한국섬유공학회 2020 Fibers and polymers Vol.21 No.9

Natural fibers reinforced composites (NFCs) have renewable and low cost advantages. In this paper, the tung oilanhydride (TOA) modified polypropylene (PP)/hemp fiber composites have been prepared by a melt-blended process. Thereaction between the tung oil anhydride and the as-treated hemp fiber make the TOA molecules to accumulate on the surfaceof hemp fiber and to form a TOA layer on the surface of hemp fibers, which is confirmed by the FT-IR and SEM analyses. The TOA layer improves the compatibility between PP matrix and hemp fibers. The elongation at break (EB) and impactstrength of the PP/hemp fiber/TOA composites are twice more than the PP/hemp fiber composites. Thermal analysis showsthe Toneset and Tmax of the composites increasing that reflects the thermal stability of the composites improved. The crystallineproperty reveals that the Tc moves to high temperature with the TOA or hemp fiber added in the blends. The DMA andrheology properties analysis indicate that the TOA layer improved molecular mobility of the composites and show a shearthinning effect.

Interplay of Intramolecular Noncovalent Coulomb Interactions for Semicrystalline Photovoltaic Polymers

Uddin, Mohammad Afsar,Lee, Tack Ho,Xu, Shuhao,Park, Song Yi,Kim, Taehyo,Song, Seyeong,Nguyen, Thanh Luan,Ko, Seo-jin,Hwang, Sungu,Kim, Jin Young,Woo, Han Young American Chemical Society 2015 Chemistry of materials Vol.27 No.17

<P>Four different kinds of photovoltaic polymers were synthesized by controlling the intrachain noncovalent coulomb interactions through the incorporation of alkoxy- or alkylthio-substituted phenylene, 4,7-di(furan-2-yl)benzothiadiazole, and 4,7-di(thiophen-2-yl)benzothiadiazole as a building block. Fine modulation of the interplay of dipole–dipole, H-bond, and chalcogen–chalcogen interactions (O···S, O···H, S···S, S···F, etc.) along the polymeric backbone influenced the chain planarity, interchain organization, film morphology, and electrical and photovoltaic properties significantly. By replacing the alkoxy substituents with alkylthio groups, the torsional angle increased (136–168°) due to the absence of an O···S attractive coulomb interaction (and/or increased S···S steric hindrance), enhancing the amorphous nature with hindered interchain packing. The alkoxy-substituted polymers exhibited nanofibrillar structures, showing strong interlamellar scattering peaks up to (300) with tight face-on <I>π–π</I> stacking in grazing incidence X-ray scattering. The measured carrier mobility of the alkoxy-containing polymers was 1–2 orders of magnitude higher than that of the alkylthio-containing polymers. The incident-light-intensity-dependent photovoltaic characteristics clearly suggested efficient charge generation/extraction with less charge recombination for the alkoxy-containing semicrystalline polymers. The resulting photovoltaic energy conversion efficiency of the PPDT2FBT, PPDF2FBT, PPsDF2FBT, and PPsDT2FBT blended devices with PC<SUB>70</SUB>BM was measured to be 8.28%, 5.63%, 5.12%, and 0.55%, respectively. This study suggests an important molecular design guideline for the further optimization of photovoltaic polymers and devices by finely controlling the interplay of the weak noncovalent coulomb interactions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-17/acs.chemmater.5b02251/production/images/medium/cm-2015-02251p_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b02251'>ACS Electronic Supporting Info</A></P>

Hydrogen bonding and noncovalent interaction can make crystalline high efficiency polymer for polymer solar cell and exceeding over 9% PCE

우딘 모하메드 압살,이택호,Thanh Luan Nguyen,Shuhao Xu,최효성,고서진,김태효,황승구,김진영,우한영 한국고분자학회 2014 한국고분자학회 학술대회 연구논문 초록집 Vol.2014 No.10

Minimizing the Number of Transitions of 3D Printing Nozzles Using a Traveling-Salesman-Problem Optimization Model

Hao Liu,Rui Liu,Zhoupeng Liu,Shuhao Xu 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.9

In nozzle-based three-dimensional printing, transitions are movements of the printing nozzle from a path endpoint to a path start-point. These transitions diminish printing quality by causing strings. A method to minimize the number of transitions based on direction-parallel line segments is presented in this paper. The endpoints of line segments were considered to be “cities” in converting the problem of minimizing the number of transitions into a traveling salesman problem (TSP). A genetic algorithm solver was developed by designing an oriented mutation method for the TSP. Compared with other algorithms for solving the TSP, our algorithm generates paths with fewer transitions. The algorithm was tested using several fused-deposition-modeling and weld arc additive manufacture examples to confirm that the generated paths were reasonable.

Benzotriazole-Containing Planar Conjugated Polymers with Noncovalent Conformational Locks for Thermally Stable and Efficient Polymer Field-Effect Transistors

Yum, Seungjib,An, Tae Kyu,Wang, Xiaowei,Lee, Wonho,Uddin, Mohammad Afsar,Kim, Yu Jin,Nguyen, Thanh Luan,Xu, Shuhao,Hwang, Sungu,Park, Chan Eon,Woo, Han Young American Chemical Society 2014 Chemistry of materials Vol.26 No.6

<P>We report a series of benzotriazole-based semicrystalline π-conjugated polymers with noncovalent conformational locks for applications in polymer field-effect transistors. The benzotriazole moiety is a versatile electron-deficient building block that offers two chemically functionalizable sites, 2(N) and 5, 6(C) positions, allowing easy modulation of the solution processability and electronic structures of the resulting polymers. Fluorine or alkoxy substituents were introduced to the benzotriazole unit to enhance the molecular ordering through intra- and intermolecular F···S, F···H–C, C–F···π<SUB>F</SUB>, or S···O attractive interactions. The fluorinated polymer (<B>PTBTz-F</B>) showed remarkably enhanced hole mobility (μ<SUB>h</SUB> = 1.9 cm<SUP>2</SUP>/(V·s), on/off ratio = 8 × 10<SUP>7</SUP>) upon thermal annealing at 305 °C, compared to the unsubstituted one (<B>PTBTz</B>) (μ<SUB>h</SUB> = 7.0 × 10<SUP>–3</SUP> cm<SUP>2</SUP>/(V·s), on/off ratio = 3 × 10<SUP>6</SUP>). Alkoxy unit substitution (<B>PTBTz-OR</B>) also improved the carrier mobility up to 0.019 cm<SUP>2</SUP>/(V·s) with an on/off ratio of 4 × 10<SUP>5</SUP>. Fluorine or alkoxy substitution induced tight interchain ordering with edge-on orientation, as confirmed by X-ray diffraction measurements. In particular, fluorinated <B>PTBTz-F</B> showed high thermal stability (<I>T</I><SUB>d</SUB> 453 °C) and the remarkable device characteristics with deep frontier orbital levels.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-6/cm4042346/production/images/medium/cm-2013-042346_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm4042346'>ACS Electronic Supporting Info</A></P>

Thienothiophene-benzotriazole-based semicrystalline linear copolymers for organic field effect transistors

Yum, Seungjib,An, Tae Kyu,Wang, Xiaowei,Uddin, Mohammad Afsar,Nguyen, Thanh Luan,Xu, Shuhao,Ryu, Hwasook,Kim, Yu Jin,Hwang, Sungu,Park, Chan Eon,Woo, Han Young De Gruyter 2014 Pure and Applied Chemistry Vol.86 No.8

<P><B>Abstract</B></P><P>A series of thienothiophene-benzotriazole-based semicrystalline copolymers,<B>PTTBTz</B>,<B>PTTBTz-F</B>, and<B>PTTBTz-OR</B>, were synthesized by considering chain linearity, planarity and inter-chain packing by virtue of non-covalent attractive interaction. Fluorine and alkoxy substituents were introduced to modulate the intra- and inter-chain coulombic interactions and crystalline ordering. The fluorine and alkoxy-substituted<B>PTTBTz-F</B>and<B>PTTBTz-OR</B>showed pronounced inter-chain packing with edge-on orientation confirmed by UV-vis absorption and X-ray diffraction measurements. The well-resolved diffraction patterns were obtained for<B>PTTBTz-F</B>and<B>PTTBTz-OR</B>, showing (100)∼(500) inter-lamellar scattering peaks (d-spacing, 17∼18 Å) in the out-of-plane direction and a π-π stacking peak (d-spacing, 3.5∼4.1 Å) in the in-plane direction. Organic field effect transistor (OFET) devices were fabricated with a bottom gate and top contact geometry.<B>PTTBTz-F</B>(<I>μ</I><SUB>h</SUB>= 4.49 × 10<SUP>-2</SUP>cm<SUP>2</SUP>V<SUP>-1</SUP>s<SUP>-1</SUP>, on/off ratio = 1.13 × 10<SUP>7</SUP>) and<B>PTTBTz-OR</B>(<I>μ</I><SUB>h</SUB>= 8.39 × 10<SUP>-3</SUP>cm<SUP>2</SUP>V<SUP>-1</SUP>s<SUP>-1</SUP>, on/off ratio = 2.98 × 10<SUP>4</SUP>) showed nearly 3 and 2 orders of magnitude higher hole mobility upon annealing at 305 and 260 °C, with compared to the unsubstituted<B>PTTBTz</B>.</P>