scholarly journals Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1260
Author(s):  
Bimlesh Lochab ◽  
Monisha Monisha ◽  
Nagarjuna Amarnath ◽  
Pratibha Sharma ◽  
Sourav Mukherjee ◽  
...  
Keyword(s):  
Low Temperature ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
The Third ◽  
Current Review ◽  
Ring Opening Reactions ◽  
Evolution Of Structure ◽  
Areas Of Interest

Due to their outstanding and versatile properties, polybenzoxazines have quickly occupied a great niche of applications. Developing the ability to polymerize benzoxazine resin at lower temperatures than the current capability is essential in taking advantage of these exceptional properties and remains to be most challenging subject in the field. The current review is classified into several parts to achieve this goal. In this review, fundamentals on the synthesis and evolution of structure, which led to classification of PBz in different generations, are discussed. Classifications of PBzs are defined depending on building block as well as how structure is evolved and property obtained. Progress on the utility of biobased feedstocks from various bio-/waste-mass is also discussed and compared, wherever possible. The second part of review discusses the probable polymerization mechanism proposed for the ring-opening reactions. This is complementary to the third section, where the effect of catalysts/initiators has on triggering polymerization at low temperature is discussed extensively. The role of additional functionalities in influencing the temperature of polymerization is also discussed. There has been a shift in paradigm beyond the lowering of ring-opening polymerization (ROP) temperature and other areas of interest, such as adaptation of molecular functionality with simultaneous improvement of properties.

scholarly journals Oncogenic Functions and Clinical Significance of Circular RNAs in Colorectal Cancer

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3395
Author(s):  
Maria Radanova ◽  
Galya Mihaylova ◽  
Neshe Nazifova-Tasinova ◽  
Mariya Levkova ◽  
Oskan Tasinov ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Drug Targets ◽  
Clinicopathological Characteristics ◽  
Circular Rnas ◽  
Diagnostic Biomarkers ◽  
The Third ◽  
Current Review ◽  
Important Challenge ◽  
Prediction Of Metastasis

Colorectal cancer (CRC) is ranked as the second most commonly diagnosed disease in females and the third in males worldwide. Therefore, the finding of new more reliable biomarkers for early diagnosis, for prediction of metastasis, and resistance to conventional therapies is an important challenge in overcoming the disease. The current review presents circular RNAs (circRNAs) with their unique features as potential prognostic and diagnostic biomarkers in CRC. The review highlights the mechanism of action and the role of circRNAs with oncogenic functions in the CRC as well as the association between their expression and clinicopathological characteristics of CRC patients. The comprehension of the role of oncogenic circRNAs in CRC pathogenesis is growing rapidly and the next step is using them as suitable new drug targets in the personalized treatment of CRC patients.

Poly(D,L-lactide/∊-Caprolactone)/Hydroxyapatite Composites as Bone Filler: An in Vivo Study in Rats

2002 ◽  
Vol 25 (12) ◽  
pp. 1174-1179 ◽  
Author(s):  
A. şenköylü ◽  
E. Ural ◽  
K. Kesencì ◽  
A. şìmşek ◽  
ş. Ruacan ◽  
...  
Keyword(s):  
Ring Opening ◽  
Bone Growth ◽  
Bone Defects ◽  
Ring Opening Polymerization ◽  
New Bone Formation ◽  
The Third ◽  
Bone Filler ◽  
Green Polymer ◽  
Animal Tests

In this study, a novel composite bone substitute was implanted in animal models (rats) and their in vivo characteristics were examined. A D,L-lactide and ∊-caprolactone copolymer (Mw: 80,000; Mn:40,000, and PI:2.00) was synthesized by ring-opening polymerization of the respective dimers using stannous octoate as the catalyst. The final ratio of D,L-lactide to ∊-caprolactone obtained by 1NMR was 60/40. Hydroxyapatite (HA) powder was loaded in the copolymer. The HA/copolymer ratio was 60/40 (w/w). These composites were easily shaped by hand. Animal tests were performed on mature wistar rats (n=30). Defects were created on the proximal, the thickest part of the femur. The bone defects of the first group were filled with polymer/HA composite, the second group filled with only HA and the third group was left empty. Histologic examination of bone tissues showed new bone formation around the yellow-green polymer/HA composite material in the first group of animals whereas no evidence of new bone growth was observed in other groups.

scholarly journals DFT Modeling of Organocatalytic Ring-Opening Polymerization of Cyclic Esters: A Crucial Role of Proton Exchange and Hydrogen Bonding

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2078 ◽  
Author(s):  
Ilya Nifant’ev ◽  
Pavel Ivchenko
Keyword(s):  
Ring Opening ◽  
Density Functional ◽  
Comparative Modeling ◽  
Ring Opening Polymerization ◽  
Proton Exchange ◽  
Dft Methods ◽  
Experimental Proof ◽  
Cyclic Esters ◽  
Dft Modeling

Organocatalysis is highly efficient in the ring-opening polymerization (ROP) of cyclic esters. A variety of initiators broaden the areas of organocatalysis in polymerization of different monomers, such as lactones, cyclic carbonates, lactides or gycolides, ethylene phosphates and phosphonates, and others. The mechanisms of organocatalytic ROP are at least as diverse as the mechanisms of coordination ROP; the study of these mechanisms is critical in ensuring the polymer compositions and architectures. The use of density functional theory (DFT) methods for comparative modeling and visualization of organocatalytic ROP pathways, in line with experimental proof of the structures of the reaction intermediates, make it possible to establish these mechanisms. In the present review, which continues and complements our recent manuscript that focused on DFT modeling of coordination ROP, we summarized the results of DFT modeling of organocatalytic ROP of cyclic esters and some related organocatalytic processes, such as polyester transesterification.

The role of ligand redox non-innocence in ring-opening polymerization reactions catalysed by bis(imino)pyridine iron alkoxide complexes

2017 ◽  
Vol 46 (38) ◽  
pp. 12971-12980 ◽  
Author(s):  
K. R. Delle Chiaie ◽  
A. B. Biernesser ◽  
M. A. Ortuño ◽  
B. Dereli ◽  
D. A. Iovan ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Oxidation States ◽  
Polymerization Catalysts ◽  
Iron Based

The reactivity of iron-based ring opening polymerization catalysts is compared when the catalyst is in three different oxidation states.

Low Temperature Ring-Opening Polymerization of Diglycolide Using Organocatalysts with PEG as Macroinitiator

2016 ◽  
Vol 217 (7) ◽  
pp. 842-849 ◽  
Author(s):  
Viviane Mawamba Kemo ◽  
Christian Schmidt ◽  
Yufei Zhang ◽  
Sabine Beuermann
Keyword(s):  
Low Temperature ◽  
Ring Opening ◽  
Ring Opening Polymerization

Ring Opening Polymerization of ε-Caprolactone Catalyzed with Magnesium Lactate

2009 ◽  
Vol 610-613 ◽  
pp. 1208-1210 ◽  
Author(s):  
Lian Liu ◽  
Zhi Yong Wei ◽  
Pei Wang ◽  
Min Qi
Keyword(s):  
Nmr Spectroscopy ◽  
Reaction Temperature ◽  
13C Nmr ◽  
Ring Opening ◽  
Synthesis Method ◽  
13C Nmr Spectroscopy ◽  
Ring Opening Polymerization ◽  
Moderate Activity ◽  
Lactide Copolymers

The aim of this paper is to present a synthesis method of poly(ε-caprolactone) by the ring opening polymerization of ε-caprolactone catalyzed with nontoxic magnesium lactate. The results indicated that Mg(Lac)2 is a catalyst with moderate activity for the polymerization of ε-caprolactone. Effects of the catalyst and reaction temperatures on the microstructure of the ε-caprolactone and L-lactide copolymers were investigated by means of 13C-NMR spectroscopy. An increase in the reaction temperature enhances the role of transesterification and the extent of randomness.

scholarly journals The preparation and properties of 1,1-difluorocyclopropane derivatives

2021 ◽  
Vol 17 ◽  
pp. 245-272
Author(s):  
Kymbat S Adekenova ◽  
Peter B Wyatt ◽  
Sergazy M Adekenov
Keyword(s):  
Ring Opening ◽  
Organic Molecules ◽  
Biological Importance ◽  
Ring Opening Reactions

Recently, the functionalization of organic molecules with fluorine substituents has grown rapidly due to its applications in such fields as medicine, agriculture or materials sciences. The aim of this article is to review the importance of 1,1-difluorocyclopropane derivatives in synthesis. It will examine the role of the fluorine substituents in both ring-forming and ring-opening reactions, as well as methods for obtaining difluorocyclopropanes as single enantiomers. Several examples are provided to highlight the biological importance of this class of compounds.

The Role of Nitrogen Donors in Zinc Catalysts for Lactide Ring-Opening Polymerization

2016 ◽  
Vol 55 (18) ◽  
pp. 9445-9453 ◽  
Author(s):  
Tannaz Ebrahimi ◽  
Emiliya Mamleeva ◽  
Insun Yu ◽  
Savvas G. Hatzikiriakos ◽  
Parisa Mehrkhodavandi
Keyword(s):  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Nitrogen Donors
Sign in / Sign up

Export Citation Format

Share Document