scholarly journals Synthesis and characterization of low-molecular-weight π-conjugated polymers covered by persilylated β-cyclodextrin

2012 ◽  
Vol 8 ◽  
pp. 1505-1514 ◽  
Author(s):  
Aurica Farcas ◽  
Ana-Maria Resmerita ◽  
Andreea Stefanache ◽  
Mihaela Balan ◽  
Valeria Harabagiu
Keyword(s):  
Molecular Weight ◽  
Condensation Reaction ◽  
Average Molecular Weight ◽  
Coupling Reaction ◽  
Morphological Properties ◽  
Blocking Group ◽  
Suzuki Coupling Reaction ◽  
Afm Analysis ◽  
Ft Ir

The paper reports the preparation of a poly[2,7-(9,9-dioctylfluorene)-alt-5,5'-bithiophene/PS-βCD] (PDOF-BTc) polyrotaxane copolymer, through a Suzuki coupling reaction between the 5,5'-dibromo-2,2'-bithiophene (BT) inclusion complex with persilylated β-cyclodextrin (PS-βCD), and 9,9-dioctylfluorene-2,7-bis(trimethylene borate) (DOF) as the blocking group. The chemical structure and the thermal and morphological properties of the resulting polyrotaxane were investigated by using NMR and FT-IR spectroscopy, TGA, DSC and AFM analysis. The encapsulation of BT inside the PS-βCD cavity results in improvements in the solubility, as well as in different surface morphology and thermal properties of the PDOF-BTc rotaxane copolymer compared to its noncomplexed PDOF-BT homologue. In contrast, the number-average molecular weight (M n) of PDOF-BTc rotaxane copolymer indicated lower values suggesting that the condensation reaction is subjected to steric effects of the bulkier silylated groups, affecting the ability of the diborate groups from the DOF molecule to partially penetrate the PS-βCD cavity.

Determination of Molecular Weight and Structure Characterization of Canna Amylose Purified Using the Method of n-Butanol Recrystallization

2012 ◽  
Vol 554-556 ◽  
pp. 1216-1222
Author(s):  
Hai Xin Shi ◽  
Yan Zhen Yin ◽  
Xiao Xi Hu ◽  
Shu Fei Jiao
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Structure Characterization ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Granule Surface ◽  
Chemical Groups ◽  
Ubbelohde Viscometer

The canna amylose (CAM) was separated from canna starch grown in China and purified both using the method of n-butanol recrystallization. The purity, morphology, spectral properties and molecular weight of CAM were characterized by ultraviolet and visible spectrophotometer (UV/Vis), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscope (FT-IR) and Ubbelohde viscometer. Maximum absorption wavelength of the purified CAM (635－638 nm) and it’s blue values (BV) (1.167 ± 0.209) prove that the purification of the CAM by n-butanol recrystallization was successfully carried out. The SEM results show that CAM granule surface become rougher and the CAM granule size become smaller than that of canna starch. The XRD results suggest that most of CAM granule is amorphous. And the FT-IR results show that the basic chemical groups of canna starch are also presented in CAM. However, the amorphous area of CAM is increased. The intrinsic viscosity and viscosity-average molecular weight of CAM is 78.5 mL/g and 1.65×105, respectively.

Synthesis and characterization of poly(coumarin-urethane)s

1994 ◽  
Vol 6 (3) ◽  
pp. 257-262
Author(s):  
D I Brahmbbatt ◽  
L Jayabalan ◽  
Harshad D Patel
Keyword(s):  
Molecular Weight ◽  
Elemental Analysis ◽  
Vapour Pressure ◽  
Condensation Reaction ◽  
Average Molecular Weight ◽  
Spectral Studies ◽  
Synthesis And Characterization ◽  
Molecular Weight Determination ◽  
Number Average Molecular Weight

Poly(coumarin-urethane)s (PCUs) were prepared by the condensation reaction of 3,3'-dihydroxy-6,6'-methylcnebiscoumarin (DHMBC) with various diisocyanates. All the poly(coumarin-urethane)s were characterized by elemental analysis, IR spectral studies, number average molecular weight determination (by vapour pressure osmometry), viscosity studies and thermogravimetry.

Preparation and characterization of glycopolymers with biphenyl spacers via Suzuki coupling reaction

2021 ◽  
Author(s):  
Hirokazu Seto ◽  
Takumi Tono ◽  
Akiko Nagaoka ◽  
Mai Yamamoto ◽  
Yumiko Hirohashi ◽  
...  
Keyword(s):  
Coupling Reaction ◽  
Suzuki Coupling ◽  
Side Chains ◽  
Suzuki Coupling Reaction ◽  
Reactant Concentration

Poly(vinylbiphenyl)s bearing glycoside ligands at the side chains were prepared using the Suzuku coupling reaction. Effects of glycoside reactant concentration, halide species, glycoside species, and catalyst species on the incorporation...

Behavior of xylans from the Eucalyptus species. Part 2. Characterization of 4-O-methylglucuronoxylans isolated from black liquors of kraft pulping of Eucalyptus grandis and E. urophylla

Holzforschung ◽  
2013 ◽  
Vol 67 (2) ◽  
pp. 123-128
Author(s):  
Andréia S. Magaton ◽  
Teresa Cristina F. Silva ◽  
Jorge Luiz Colodette ◽  
Dorila Piló-Veloso ◽  
Flaviana Reis Milagres ◽  
...  
Keyword(s):  
Average Molecular Weight ◽  
Eucalyptus Grandis ◽  
Kraft Pulping ◽  
Raw Material ◽  
Size Exclusion ◽  
Eucalyptus Species ◽  
Exclusion Chromatography ◽  
Ft Ir ◽  
Black Liquors

Abstract 4-O-methylglucuronoxylans isolated from Eucalyptus grandis and Eucalyptus urophylla kraft black liquors (KBLs) were chemically characterized by Fourier transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), and nuclear magnetic resonance (NMR) spectroscopy. Doses of alkali charge, expressed as active alkali (AA), were 16, 17, and 18% while the sulfidity was kept at 25%. Kappa numbers of 19.1, 17.5, and 16.1 for E. grandis and 20.4, 16.8, and 15.4 for E. urophylla were obtained. At higher alkali charges, the recovery of xylans from the KBLs was lower and the degree of substitution of xylans with uronic acids decreased. The average molecular weight (Mw) of the recovered xylans was greater under conditions of mild pulping, i.e., in the case of pulps with higher kappa numbers. Mw of xylans ranged from 16.1 to 19.1 kDa for E. grandis and from 15.4 to 20.4 kDa for E. urophylla. The xylans from KBL may be useful as pulp modifying agents or as a raw material for advanced applications.

Study on the Preparation and Characterization of Carboxyl Terminated Poly(L-Lactic Acid) (PLLA) Prepolymers

2017 ◽  
Vol 872 ◽  
pp. 165-170
Author(s):  
Shi Chao Lu ◽  
Yang Chuan Ke ◽  
Qian Zhou ◽  
Zhao Rui Meng ◽  
Guo Liang Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Average Molecular Weight ◽  
Polymerization Temperature ◽  
Capping Agent ◽  
Molar Amount ◽  
Optimum Reaction ◽  
Catalyst Content ◽  
End Capping

The carboxyl terminated poly (L-lactic acid) (PLLA) prepolymers were prepared via polycondensation of L-lactic acid and 1,6-adipic acid (end capping agent) under the catalyst of stannous octoate. The effects of synthetic condition, such as reaction temperature, amount of catalyst, content of the end capping agent, etc, on the molecular weight of PLLA were discussed. Fourier transform infrared and 1H nuclear magnetic resonance were used to characterize the PLLA prepolymers. The results indicated that the polycondensation was performed under an optimum reaction condition as following: the amount of the catalyst was 500 ppm based on the mass of lactic acid, the amount of the end capping agent was 1% (the molar amount of the lactic acid), and the polymerization temperature was 170 °C. The viscosity-average molecular weight of the product reached 2.826×104 at this polymerization temperature and the yield was 73.34%.

ATRP Synthesis and Characterization of μ,αω-allyl-terminated Macromonomers as Precursors for End-linked Gels and Hydrogels

2003 ◽  
Vol 774 ◽  
Author(s):  
Lucy Vojtova ◽  
Nicholas J. Turro ◽  
Jeffrey T. Koberstein
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Monomer Conversion ◽  
Catalyst System ◽  
Linear Increase ◽  
Butyl Methacrylate ◽  
First Order Kinetics ◽  
Significant Difference ◽  
Ft Ir

AbstractSynthesis of α,ω-allyl-terminated telechelic macromonomers based on poly(tert-butyl methacrylate) (poly(t-BMA)) and poly(methacrylic acid) (poly(MAA)) was studied with the aim of preparing end-linked gels and hydrogels. Low molecular weight α-allyl-terminated poly(t-BMA) macromonomers with narrow polydispersities (Mw/Mn = 1.16) were synthesized via controlled atom transfer radical polymerization (ATRP) using a Cu(I)Br/N,N,N',N',N',N'-hexamethyltriethylenetetraamine catalyst system in conjunction with an allyl-2-bromoisobutyrate as the functional initiator. The polymerizations exhibited a linear increase of molecular weight in direct proportion to the monomer conversion and first-order kinetics with respect to monomer concentration. No significant difference was found between using polar or non-polar solvents (tetrahydrofuran or benzene, respectively). Optimization of reaction conditions to obtain the highest degree of active terminal bromine is discussed. Quenching the ATRP reaction with allyltributyltin yielded α,ω-allyl-terminated poly(t-BMA) macromonomers by replacing the terminal bromine with ω-allyl functional group. Poly(MAA) macromonomers were prepared by deprotection of the tert-butyl group from α,ω-allyl-terminated poly(t-BMA) macromonomers using concentrated trifluoroacetic acid at room temperature. Successful synthetic steps were confirmed by 1H NMR, FT-IR and MALDI-TOF MS analyses. The α,ω-allyl-terminated macromonomers were proven to be candidates for further polymerization by forming end-linked, non-soluble gels.

Conductive Polymers Based on Phenothiazine-Benzothiadiazole: Synthesis, Characterization of Photovoltaics

2013 ◽  
Vol 634-638 ◽  
pp. 2643-2650 ◽  
Author(s):  
Dae Hee Yun ◽  
Han Sol Yoo ◽  
Tae Won Ko ◽  
Yong Sung Park ◽  
Je Wan Woo
Keyword(s):  
Conjugated Polymers ◽  
Power Conversion ◽  
Coupling Reaction ◽  
Band Gap Energy ◽  
Suzuki Coupling Reaction ◽  
Gap Energy ◽  
Solution State ◽  
Conversion Efficiencies ◽  
Film State

Two new π-conjugated polymers (Poly[(N-10’-(octan-3-yl)-phenothiazin-3,7-ylene)-alt- (4’,7’-bis(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PoPTZ-BT-BTD), Poly[(N-10`-(octan-3-yl) -phenothiazin-3,7-ylene)-alt-(4’,7’-bis(thiophen-2-yl)-5,6-bis(octyloxy)benzo[c][1,2,5]thiadiazole)] (PoPTZ-BT-BoBTD) ) were synthesized through the Suzuki coupling reaction for organic photovoltaics (OPVs), and their optical and electrochemical properties were analyzed. Their wavelength of maximun absorption was 526 nm and 506 nm in solution state, repectively, and 560 nm and 522 nm in film state, respectively. Their band-gap energy was 2.01 eV and 2.09 eV in solution state, and 1.82 eV and 1.91 eV in film state, respectively. The results of analysis of the chrateristics of photovoltaics, 0.79 % and 0.99 % of the maximum power conversion efficiencies (PCE), repectively.

scholarly journals Molecular Characterization of Arabinoxylan from Wheat Beer, Beer Foam and Defoamed Beer

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1230
Author(s):  
Jie Li ◽  
Jinhua Du
Keyword(s):  
Molecular Weight ◽  
Molecular Characterization ◽  
Average Molecular Weight ◽  
Monosaccharide Composition ◽  
Weight Average Molecular Weight ◽  
Substitution Degree ◽  
Significant Difference ◽  
Spherical Structures ◽  
Beer Foam

This research was to explore the distribution and some molecular characterization of arabinoxylan in wheat beer (B), beer foam (BF) and defoamed beer (DB) because of the crucial influences of arabinoxylan on wheat beer and its foam. The purified arabinoxylan from B, BF, and DB were fractionated by ethanol of 50%, 67%, 75%, and 80%. The monosaccharide composition, substitution degree (Ara/Xyl ratio, A/X), and average degrees of polymerization (avDP) of arabinoxylan were investigated. Molecular weight and microstructure were also involved in this study by GPC-LLS and SEM, respectively. Under the same ethanol concentration, the arabinoxylan content in the BF was higher than the other two, respectively, and it was precipitated in BF fraction with 50% ethanol which accounted for 80.84% of the total polysaccharides. Meanwhile, the greatest substitution degree (A/X) and highest value of avDP of the arabinoxylan was found in all beer foam fractions regardless of the concentration of ethanol used. The average degrees of polymerization (avDP) of arabinoxylan displayed a significant difference (p < 0.05) among B, BF, and DB. Furthermore, arabinoxylan presented varied microstructure with irregular lamellas and spherical structures and the weight-average molecular weight (Mw) of arabinoxylan showed the lowest values in BF, while the largest values were shown in DB. Therefore, arabinoxylan was more accumulated in beer foam, especially in 50% ethanol, characterised by greater value of A/X and avDP, as well as lower Mw. It was suggested that the arabinoxylan played important roles in maintaining wheat beer foam characteristics.

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