scholarly journals Synthesis, molecular and morphological characterization of linear and complex architecture block copolymers consisting of poly(cyclohexadiene)

2012 ◽  
Author(s):  
Κωνσταντίνος Μισιχρόνης
Keyword(s):  
Block Copolymers ◽  
1H Nmr ◽  
Morphological Characterization ◽  
Complex Architecture

Στην συγκεκριμένη ερευνητική εργασία περιγράφεται η σύνθεση μέσω ανιοντικού πολυμερισμού 17 γραμμικών δισυσταδικών συμπολυμερών του τύπου PS-b-PCHD ή PS-b-PCHD όπου PS: πολυστυρένιο και PCHD: πολυ(κυκλοεξαδιένιο) καθώς και 5 συμπολυμερών πολύπλοκης αρχιτεκτονικής αποτελούμενα επίσης από PS και PCHD. Τα πολύπλοκης αρχιτεκτονικής δείγματα αποτελούν ένα (1) γραμμικό τρισυσταδικό συμπολυμερές (PCHD-b-PS-b-PCHD), ένα (1) γραμμικό πεντασυσταδικό συμπολυμερές [(PS-b-PCHD)-PS-(PCHD-b-PS)], ένα (1) H-type συμπολυμερές [(PCHD)2-PS-(PCHD)2] και δύο (2) super H-type συμπολυμερή [(PCHD)3-PS-(PCHD)3 και (PS-b-PCHD)3-PS-(PCHD-b-PS)3].Η σύνθεση των δειγμάτων ολοκληρώθηκε με την χρήση της γραμμής υψηλού κενού και την μέθοδο της διαδοχικής προσθήκης μονομερών. Για τον πολυμερισμό χρησιμοποιήθηκε sec-BuLi σε βενζόλιο, ενώ χρησιμοποιήθηκε και το πολικό συστατικό DABCO ώστε η συστάδα του PCHD να εμφανίζει υψηλή 1,4-μικροδομή (87-98%). Συντέθηκε ένα μεγάλο εύρος κλασμάτων όγκου (0.25 < φPS < 0.94) έτσι ώστε να εξεταστεί αναλυτικά η μορφολογική συμπεριφορά του συστήματος. Η σύνθεση των πολύπλοκης αρχιτεκτονικής συμπολυμερών περιελάμβανε την χρήση του διδραστικού απαρχητή Na/ναφθαλίνιο ώστε να συντεθεί το διδραστικό πολυστυρένιο. Ο πολυμερισμός πραγματοποιήθηκε σε διάλυμα βενζολίου/THF σε αναλογία 1,2:1 και η αντίδραση σύζευξης με τα ενεργά άκρα, που αποτελούνταν είτε από PCHD ή από (PS-b-PCHD), πραγματοποιήθηκε χρησιμοποιώντας γνωστή χημεία χλωροσιλανίων. Πιο συγκεκριμένα τρία χλωροσιλάνια χρησιμοποιήθηκαν, το (CH3)2SiCl2, (CH3)SiCl3 και το SiCl4 ώστε να συζευχθούν με την διδραστική συστάδα (Na(+)(-)PS(-)(+)Na) και στην συνέχεια με τα ζωντανά άκρα αποτελούμενα από PCHD ή από (PS-b-PCHD).Ο μοριακός χαρακτηρισμός των δειγμάτων πραγματοποιήθηκε μέσω της χρωματογραφίας αποκλεισμού μεγεθών (SEC) και οσμομετρίας μεμβράνης (MO) ώστε να πιστοποιηθούν τα μέσα μοριακά βάρη κατά αριθμό και οι κατανομές μοριακών βαρών. Επίσης χρησιμοποιήθηκε η φασματοσκοπία πυρηνικού μαγνητικού συντονισμού πρωτονίου (1H-NMR) ώστε να επιβεβαιωθούν τα κλάσματα μάζας, καθώς επίσης και να υπολογιστούν τα ποσοστά των μικροδομών 1,2- και 1,4- για την συστάδα του PCHD. Επίσης, υιοθετήθηκε η διαφορική θερμοδομετρία σάρωσης (DSC) ώστε να προσδιοριστούν οι θερμοκρασίες υαλώδους μετάπτωσης (Tg) των δειγμάτων.Τέλος, ο μορφολογικός χαρακτηρισμός των δισυσταδικών συμπολυμερών πραγματοποιήθηκε με ηλεκτρονική μικροσκοπία διέλευσης (TEM) και σκέδαση ακτινών-Χ υπό μικρές γωνίες (SAXS). Παρατηρήθηκαν όλες οι γνωστές μορφολογίες από την βιβλιογραφία αλλά για διαφορετικά κλάσματα όγκου από τα αναμενόμενα, ενώ μοναδικές μορφολογίες παρατηρήθηκαν προσφέροντας νέες πληροφορίες για τον μικροφασικό διαχωρισμό του συστήματος PS-b-PCHD. Επίσης, πιο αναλυτικές μετρήσεις μέσω SAXS πρέπει να πραγματοποιηθούν ώστε να επιβεβαιωθούν οι μορφολογίες που παρατηρούνται μέσω ΤΕΜ.

Morphological Characterization of Elastin-Mimetic Block Copolymers Utilizing Cryo- and Cryoetch-HRSEM

2003 ◽  
Vol 9 (3) ◽  
pp. 171-182 ◽  
Author(s):  
Elizabeth R. Wright ◽  
Vincent P. Conticello ◽  
Robert P. Apkarian
Keyword(s):  
Block Copolymers ◽  
High Vacuum ◽  
Three Dimensional ◽  
Sample Surface ◽  
Morphological Characterization ◽  
High Concentration ◽  
Micellar Aggregates ◽  
Hydrogel Network ◽  
Resolution Level

Elastin-mimetic block copolymers were produced by genetic engineering. Genetically driven synthesis permitted control of the final physiochemical characteristics of the block copolymers. We designed BB and BAB block copolymers in which the A-block was hydrophilic and the B-block was hydrophobic. By designing the copolymers in this manner, it was proposed that they would self-assemble into micellar aggregates that, at high concentration, would form thermoreversible hydrogels. To analyze the three-dimensional fine surface morphology of the copolymers, to the resolution level of a few nanometers, we employed cryo-HRSEM. This method provided vast expanses of the specimen in its frozen hydrated state for survey. In our initial cryo-HRSEM studies, we observed the protein filaments and micelles surrounded by lakes of vitreous ice. Upon examination at low and intermediate magnifications, there was an extensive honeycomb-like filamentous network. To delineate the fine morphology of the hydrogel network at high magnification and to greater depths, we cryoetched away unbound water from the sample surface, in high vacuum, prior to chromium deposition. By using this technique, we were able to visualize for characterization purposes the fine fibril networks formed from the micellar aggregates over the surface of the hydrogel.

scholarly journals Synthesis and morphological characterization of block copolymers for improved biomaterials

2010 ◽  
Vol 110 (6) ◽  
pp. 639-649 ◽  
Author(s):  
Scott Schricker ◽  
Manuel Palacio ◽  
B.T.S. Thirumamagal ◽  
Bharat Bhushan
Keyword(s):  
Block Copolymers ◽  
Morphological Characterization

Synthesis of PCL-PS Star-Block Copolymer by Combination of Lipase-Catalyzed Ring-Opening Polymerization and ATRP

2006 ◽  
Vol 11-12 ◽  
pp. 749-752 ◽  
Author(s):  
Rui Xue Liu ◽  
Yan Shi ◽  
Zhi Feng Fu
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
1H Nmr ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Star Block Copolymer ◽  
Star Block Copolymers

Poly(ε-caprolactone) (PCL)-polystyrene (PS)star-block copolymer with a cross-linked microgel core were synthesized by the combination of atom transfer radical polymerization (ATRP) of St and lipase-catalyzed ring-opening polymerization (ROP) of ε-CL. The characterization of PCL-Br, PCL-PS-Br macroinitiator and PCL-PS Star-block copolymers was detected by GPC and 1H NMR. Results showed that the target star-block copolymers were successfully prepared.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

Morphological Characterization of Rhinacanthus Species of Sri Lanka

Planta Medica ◽  
2010 ◽  
Vol 76 (05) ◽  
Author(s):  
APPR Amarasinghe ◽  
RP Karunagoda ◽  
DSA Wijesundara
Keyword(s):  
Sri Lanka ◽  
Morphological Characterization

Density and morphological characterization of bacteria in integrated and exclusive production systems

2020 ◽  
Vol 13 (11) ◽  
pp. 1
Author(s):  
A. R. B. Zanco ◽  
A. Ferreira ◽  
G. C. M. Berber ◽  
E. N. Gonzaga ◽  
D. C. C. Sabino
Keyword(s):  
Bacterial Community ◽  
Rainy Season ◽  
Production Systems ◽  
Cropping System ◽  
Morphological Characterization ◽  
Native Forest ◽  
Exclusive Production ◽  
Colony Forming Units

The different integrated production systems can directly interfere with its bacterial community. The present study aimed to assess density, bacterial diversity and the influence of dry and rainy season in different integrated and an exclusive production system. The fallow and a native forest area was assessed to. Samples were collected in 2012 March and September. The isolation were carried out into Petri dishes containing DYGS medium. The number of colony forming units (CFU) was counted after 48 hours and. The bacterial density ranged between 106 and 107 CFU g-1 soil. The crop system affected the dynamics of the bacterial community only in the rainy season. The rainy season showed greater density of total bacteria when compared to the dry period regardless of the cropping system. The dendrograms with 80 % similarity showed thirteen and fourteen groups in the rainy and dry seasons. Isolates with the capacity to solubilize phosphate in vitro were obtained from all areas in the two seasons, but this feature has been prevalent in bacteria isolated during the rainy season

Synthesis and Spectral Characterization of New S-Alkylated 1,2,4-Triazoles as Potential Biological Agents

2017 ◽  
Vol 68 (10) ◽  
pp. 2436-2439
Author(s):  
Stefania Felicia Barbuceanu ◽  
Laura Ileana Socea ◽  
Constantin Draghici ◽  
Elena Mihaela Pahontu ◽  
Theodora Venera Apostol ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Spectral Data ◽  
1H Nmr ◽  
Elemental Analysis ◽  
13C Nmr ◽  
Ethyl Bromide ◽  
Spectral Characterization ◽  
Basic Medium ◽  
Phenacyl Bromide

In the work we presented the behavior of 5-(4-(4-X-phenylsulfonyl)phenyl)-4-(n-propyl)-2H-1,2,4-triazole-3(4H)-thiones (X= Cl or Br) with some alkylation agents. Thus, new S-alkylated 1,2,4-triazole derivatives were synthesized by reaction of the corresponding 1,2,4-triazole-3-thione derivatives with different �-halogenated compounds (ethyl bromide, ethyl chloroacetate or phenacyl bromide), in basic medium. The structures of synthesized compounds were elucidated by spectral data (1H-NMR, 13C-NMR, mass spectrometry) and elemental analysis.

Characterization of Antibacterial-Producing Endophytic Fungi of Syzygiumpolyanthum Leaves

2020 ◽  
Vol 20 (4) ◽  
pp. 448-454
Author(s):  
Rahmita Burhamzah ◽  
Gemini Alam ◽  
Herlina Rante
Keyword(s):  
Molecular Characterization ◽  
Endophytic Fungi ◽  
Morphological Characterization ◽  
Test Method ◽  
Analysis Method ◽  
Nitrogen Base ◽  
Rdna Genes ◽  
Antibacterial Screening ◽  
Planting Method

Background: Endophytic fungi live in plants’ tissue and can produce the same bioactive compounds as its host plant produces. Syzygiumpolyanthum leaves have known to be one of the antibacterial compound producers. Aim and Objective: This study aimed to characterize morphologically, microscopically, and molecularly the antibacterial-producing endophytic fungi of Syzygiumpolyanthum leaves. Methods: The isolation of endophytic fungi was done by fragment planting method on PDA medium. The antibacterial screening was performed using the antagonistic test as the first screening followed by the disc diffusion test method. The morphological characterization was based on isolate’s mycelia color, growth pattern, margin, and surface texture of the colony, while the microscopic characterization was based on its hyphae characteristics. The molecular characterization of the isolate was done by nitrogen base sequence analysis method on nucleotide constituent of ITS rDNA genes of the isolate. Results: The results found that isolate DF1 has antibacterial activity against E.coli, S.aureus, P.acne, and P.aeruginosa, with the greatest inhibition at 10% concentration of broth fermentation extract on S.aureus with a diameter of inhibition of 13.77 mm. Conclusion: Based on macroscopic, microscopic, and molecular characterization, DF1 isolate is similar to Ceriporialacerate.

Synthesis and characterization of novel chiral derivatizing agents containing β-keto-anthracene adducts (KAAs) by 1H-NMR: aromatic influence and chiral alcohol absolute configuration determination

2019 ◽  
Vol 17 (3) ◽  
pp. 541-554
Author(s):  
Neeranuth Intakaew ◽  
Puracheth Rithchumpon ◽  
Chanatkran Prommin ◽  
Saranphong Yimklan ◽  
Nawee Kungwan ◽  
...  
Keyword(s):  
1H Nmr ◽  
Absolute Configuration ◽  
Synthesis And Characterization ◽  
Chiral Alcohols ◽  
Chiral Alcohol ◽  
Aromatic Rings ◽  
H Nmr ◽  
Chiral Derivatizing Agents

New chiral derivatizing agents and the effect of aromatic rings were investigated for absolute configuration of chiral alcohols via1H-NMR.

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