A New Green Process for Synthesising High Quality PLLA Materials

2013 ◽  
Vol 750-752 ◽  
pp. 1377-1380 ◽  
Author(s):  
Hui Li Shao ◽  
Xian Jue Zhou ◽  
Xue Chao Hu
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Ring Opening Polymerization ◽  
Green Process ◽  
Weight Average Molecular Weight ◽  
H Nmr ◽  
Ft Ir ◽  
C Nmr

Synthesis of Poly(L-lactide) (PLLA) by the ring-opening polymerization (ROP) of L-lactides in supercritical carbon dioxide (SC-CO2) with co-solvent were studied. Effects of kinds of co-solvent on the molecular weight (MW) and the molecular weight distribution (MWD) of the resultant polymers were investigated by the gel permeation chromatography (GPC). The resultant polymers were also characterized with1H NMR,13C NMR and FT-IR. It was found that PLLA with high purity and almost without racemization could be obtained by this technology and the acetone is the best co-solvent for this kind of polymerization. By using stannous octoate as initiator and acetone as co-solvent, PLLA having a weight-average molecular weight (Mw) near to 9×104and polydispersity index (PDI) of 1.7 was successfully synthesized.

Cationic copolymerization of 1,3-pentadiene with α-pinene

2014 ◽  
Vol 34 (7) ◽  
pp. 583-589 ◽  
Author(s):  
Ai-Yuan Li ◽  
Xiang-Dong Sun ◽  
Hui-Bo Zhang ◽  
Yong-Chun Zhang ◽  
Bin Wang ◽  
...  
Keyword(s):  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Polymerization Temperature ◽  
Scanning Calorimetry ◽  
Gardner Color ◽  
H Nmr ◽  
Cationic Copolymerization ◽  
Ft Ir ◽  
Better Than ◽  
C Nmr

Abstract The cationic copolymerization of 1,3-pentadiene (PD) with α-pinene (AP) initiated by aluminum trichloride (AlCl3) was carried out in N-pentane solvent. The effects of the polymerization temperature and the comonomer composition on the yield of the copolymer, softening point, Gardner color scale and number-average molecular weight (Mn) are discussed. The performance of the copolymer was better than that of AP homopolymer (PAP) and PD homopolymer (PPD). The structure of the copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR), 1H-nuclear magnetic resonance (1H-NMR), 13C-NMR, differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). In addition, the reactivity ratios for AP (M1) and PD (M2) determined by the Kelen-Tudos method from low-conversion data are r1=0.58 and r2=5.92, respectively.

scholarly journals End-Group Evaluation of HEMA Initiated Poly(ε-caprolactone) Macromonomers via Enzymatic Ring-Opening Polymerization

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
N. Ugur Kaya ◽  
Y. Avcibasi Guvenilir
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Ring Opening Polymerization ◽  
Enzyme Concentration ◽  
Polymer Chains ◽  
Side Reactions ◽  
Initiator Concentration ◽  
Lower Temperature

Poly(ε-caprolactone) (PCL) macromonomers comprising acrylate end-functionality were synthesized via enzymatic ring-opening polymerization (eROP) by utilizing commercially availableCandida antarcticaLipase B (CALB), Novozyme-435. 2-Hydroxyethyl methacrylate (HEMA) was purposed to be the nucleophilic initiator in eROP. The side reactions generated due to the cleavage of ester bonds in HEMA and the growing polymer chains were investigated through altering polymerization period, initiator concentration, temperature, and enzyme concentration.1H NMR evaluations showed that minimum quantities of side reactions were in lower temperatures, initiator concentration, enzyme concentration, and lower monomer conversions. Gel permeation chromatography (GPC) results revealed that lower polydispersity along with number-average molecular weight of end-functionalized PCL macromonomers was obtained depending on higher initiator/monomer ratios, lower temperature (60°C), enzyme concentration (100 mg), and/or polymerization time (2 h). Furthermore, 0.1 HEMA/ε-caprolactone (CL) ratio had higher molecular weight than 0.5 HEMA/CL ratio, while keeping a close value of methacrylate transfer, total methacrylate end-groups, and lower polyester transfer.

Synthesis and Characterization of a Novel Biodegradable Polymer with Fluorescence Property

2011 ◽  
Vol 197-198 ◽  
pp. 21-26
Author(s):  
Ji Hang Li ◽  
Dong Jian Shi ◽  
Na Hu ◽  
Wei Fu Dong ◽  
Jun Feng Li ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Gel Permeation Chromatography ◽  
Ring Opening Polymerization ◽  
Fluorescence Property ◽  
H Nmr ◽  
Gel Permeation ◽  
Fluorescent Polymer ◽  
Poor Solvent

In this paper, a novel biodegradable and fluorescent polymer: fluorescein-polylactide (FL-PLA) was synthesized by FL and lactide in the method of ring-opening polymerization with the catalysis of Sn(Oct)2under 130°C . The structure and molecular weight of FL-PLA were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H-NMR) spectroscopy, and gel permeation chromatography (GPC). The molecular weight of FL-PLA increased from 9.03×103to 21.24×103with decreasing the amount of FL and kept a narrow distribution. The result of differential scanning calorimeter (DSC) showed that Tgincreased from 52 to 72°C with increasing the molecular weight of polymer. Moreover, the average number content of FL in each molecular chain decreased from 0.96 to 0.81 with decrement of the amount of FL. Furthermore, FL-PLA showed the fluorescence property, and the fluorescence intensity could be controlled by the amount of FL. The FL-PLA nanoparticles were prepared by mixing the good and poor solvent, and the diameter was about 3 μm with regular spherical morphology.

scholarly journals Fast and Convenient Synthesis of Amine-Terminated Polylactide as a Macroinitiator forω-Benzyloxycarbonyl-L-Lysine-N-Carboxyanhydrides

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Mingjie Ju ◽  
Feirong Gong ◽  
Shujun Cheng ◽  
Yun Gao
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Low Molecular Weight ◽  
Amine Group ◽  
H Nmr ◽  
Convenient Synthesis ◽  
Ft Ir ◽  
Chain Lengths

Amine-terminated poly (L-lactide) (NH2-PLLA) with various chain lengths were successfully synthesized by sequential tert-butyl-N-(3-hydroxypropyl) carbamate initiated bulk ring-opening polymerization (ROP) of L-lactide (L-LA) in the presence of Stannous(II) 2-ethylhexanoate (Sn(Oct)2) and deprotection of theN-tert-butoxycarbonyl (Boc) group at the end of the polymer chain. The polymers obtained were characterized by FT-IR,1H NMR, and GPC method. NH2-PLLA thus prepared was used to initiate the polymerization of ω-benzyloxycarbonyl-L-lysine-N-carboxyanhydride (Lys (Z)-NCA), and the result confirmed the high nucleophilicity of the terminal amine group. This method was not only suitable for the preparation of low molecular weight NH2-PLLA, but also quite efficient in the synthesis of high molecular weight samples.

Synthesis of α,ω-bis(3-aminopropyldiethoxylsilane) Poly(tri fluoropropylmethyl)siloxanes

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Zhendong Shi ◽  
Xinling Wang
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Reaction Rate ◽  
Ring Opening Polymerization ◽  
Step Process ◽  
Molecular Weights ◽  
H Nmr ◽  
One Step ◽  
Ft Ir ◽  
High Yields

AbstractHigh molecular weight α,ω-bis(3-aminopropyldiethoxylsilane) poly(tri fluoropropylmethyl)siloxanes (APTFPMS) were prepared via a “one-step” process, based on the ring-opening polymerization of 1,3,5-tris(trifluoropropylmethyl) cyclotrisiloxane (F3) in the presence of water and 3-aminopropyltriethoxysilane (APTES). GPC, FT-IR and 1H NMR confirmed the structure of the polymers. It was found that the amount of APTES had significant influence on the reaction rate and the molecular weights of polymers decreased with the increasing amount of water. It was probably because both water and the amino group of APTES favoured generation of hydroxyl ions, which efficiently initiate the polymerization of F3 to achieve APTFPMS. In order to verify this mechanism, another “two-step” process was also performed: Firstly the α,ω-dihydroxylated poly(trifluoropropylmethyl) siloxanes were synthesized from F3 catalyzed by both diaminoethane and water, then reacted with APTES to achieve APTFPMS. All the syntheses had high yields and the molecular weight of the polymers ranged from 2000 to 25000.

scholarly journals Characterisation of Sequential Solvent Fractionation and Base-catalysed Depolymerisation of Treated Alkali Lignin

BioResources ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. 4137-4151 ◽  
Author(s):  
Aikfei Ang ◽  
Zaidon Ashaari ◽  
Edi Suhaimi Bakar ◽  
Nor Azowa Ibrahim
Keyword(s):  
Molecular Weight ◽  
Chemical Structure ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Solubility Parameters ◽  
Low Molecular Weight ◽  
Sequential Fractionation ◽  
Weight Average Molecular Weight ◽  
Solvent Fractionation ◽  
Alkali Lignin

An alkali lignin (OL) with a weight-average molecular weight (Mw) of 11646 g/mol was used to prepare low-molecular weight lignin for resin synthesis. The low-molecular weight lignin feedstock was obtained via base-catalysed depolymerisation (BCD) treatments at different combined severity factors. Sequential fractionation of the OL and BCD-treated lignins using organic solvents with different Hildebrand solubility parameters were used to alter the homogeneity of the OL. The yield and properties of OL itself and OL and BCD-treated OL dissolved in propan-1-ol (F1), ethanol (F2), and methanol (F3) were determined. Regardless of the treatment applied, a small amount of OL was dissolved in F1 and F2. The BCD treatment did not increase the yield of F1 but did increase the yields of F2 and F3. Gel permeation chromatography (GPC) showed that the repolymerization reaction occurred in F3 for all BCD-treated OL, so these lignins were not suitable for use as feedstocks for resin production. The GPC, 13Carbon-nuclear magnetic resonance, and Fourier transform infrared spectroscopy analyses confirmed that the F3 in OL exhibited the optimum yield, molecular weight distribution, and chemical structure suitable for use as feedstocks for resin synthesis.

Characterization of bi-layered magnetic nanoparticles synthesized via two-step surface-initiated ring-opening polymerization

2015 ◽  
Vol 87 (11-12) ◽  
pp. 1085-1097 ◽  
Author(s):  
Li Wang ◽  
Stefan Baudis ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Magnetic Nanoparticles ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Polymer Networks ◽  
Gel Permeation Chromatography ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Transmission Electron

AbstractA versatile strategy to integrate multiple functions in a polymer based material is the formation of polymer networks with defined nanostructures. Here, we present synthesis and comprehensive characterization of covalently surface functionalized magnetic nanoparticles (MNPs) comprising a bi-layer oligomeric shell, using Sn(Oct)2 as catalyst for a two-step functionalization. These hydroxy-terminated precursors for degradable magneto- and thermo-sensitive polymer networks were prepared via two subsequent surface-initiated ring-opening polymerizations (ROPs) with ω-pentadecalactone and ε-caprolactone. A two-step mass loss obtained in thermogravimetric analysis and two distinct melting transitions around 50 and 85°C observed in differential scanning calorimetry experiments, which are attributed to the melting of OPDL and OCL crystallites, confirmed a successful preparation of the modified MNPs. The oligomeric coating of the nanoparticles could be visualized by transmission electron microscopy. The investigation of degrafted oligomeric coatings by gel permeation chromatography and 1H-NMR spectroscopy showed an increase in number average molecular weight as well as the presence of signals related to both of oligo(ω-pentadecalactone) (OPDL) and oligo(ε-caprolactone) (OCL) after the second ROP. A more detailed analysis of the NMR results revealed that only a few ω-pentadecalactone repeating units are present in the degrafted oligomeric bi-layers, whereby a considerable degree of transesterification could be observed when OPDL was polymerized in the 2nd ROP step. These findings are supported by a low degree of crystallinity for OPDL in the degrafted oligomeric bi-layers obtained in wide angle X-ray scattering experiments. Based on these findings it can be concluded that Sn(Oct)2 was suitable as catalyst for the preparation of nanosized bi-layered coated MNP precursors by a two-step ROP.

Randomly Branched Polymers. II. Computer Analysis of Gel-Permeation Chromatograms

1976 ◽  
Vol 49 (5) ◽  
pp. 1290-1304
Author(s):  
M. Kurata ◽  
H. Okamoto ◽  
M. Iwama ◽  
M. Abe ◽  
T. Homma
Keyword(s):  
Molecular Weight ◽  
Weight Distribution ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Computer Method ◽  
Branched Polymers ◽  
Branch Points ◽  
Weight Average Molecular Weight ◽  
Degree Of Branching ◽  
Gel Permeation

Abstract An iterative computer method was proposed for estimating the degree of branching and molecular weight distribution simultaneously from a pair of measurements on intrinsic viscosity and gel-permeation chromatography. The validity of the method as applied to randomly branched polymers was tested by using both fractionated and unfractionated samples of branched polystyrenes. It was experimentally concluded that the average number of branch points per unit molecular weight, λ, can be determined by this method with an accuracy of about 15%, and the weight-average molecular weight with accuracy of about 10%.

scholarly journals Functional Aromatic Poly(1,3,4-Oxadiazole-Ether)s with Benzimidazole Pendants: Synthesis, Thermal and Dielectric Studies

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Shimoga D. Ganesh ◽  
Vasantakumar K. Pai ◽  
Mahadevappa Y. Kariduraganavar ◽  
Madhu B. Jayanna
Keyword(s):  
Carboxylic Acid ◽  
Average Molecular Weight ◽  
Analytical Techniques ◽  
Gel Permeation Chromatography ◽  
Electrical Contacts ◽  
Dielectric Studies ◽  
Weight Average Molecular Weight ◽  
Nucleophilic Displacement ◽  
Ft Ir

Poly(1,3,4-oxadiazole-ether) with reactive carboxylic acid pendants was synthesized from solution polymerization via nucleophilic displacement polycondensation among 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole (BFPOx) and 4,4′-bis(4-hydroxyphenyl) valeric acid (BHPA). Without altering the polymeric segments, benzimidazole modified poly(1,3,4-oxadiazole-ether)s were prepared by varying stoichiometric ratios of 1,2-phenylenediamine. The molecular structural characterization of these polymers was achieved by, FT-IR, NMR, TGA, elemental analysis, and analytical techniques. The weight-average molecular weight of virgin polymer with carboxylic acid functionality was determined by gel permeation chromatography (GPC) and was found to be 22400 (Mw/Mn=2.07). All the synthesized polyethers were compressed into pellets and electrical contacts were established to perform dielectric properties.

scholarly journals Synthesis of New Imidazolidine and Tetrahydropyrimidine Derivatives

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Hamid Beyzaei ◽  
Reza Aryan ◽  
Zahra Keshtegar
Keyword(s):  
Ring Opening ◽  
Reaction Times ◽  
Reaction Conditions ◽  
Ir Spectrometry ◽  
H Nmr ◽  
Chemical Structures ◽  
Thioamide Group ◽  
Solvent Free Conditions ◽  
Ft Ir ◽  
C Nmr

Synthesis of new imidazolidine and tetrahydropyrimidine derivatives 3a, b and 4a–c as cyclic 1,3-diamines under two reaction conditions (A and B) is described. Under reaction conditions-A, a suspension of (E)-2-cyano-2-(oxazolidin-2-ylidene)ethanethioamide 1 (1 eq.) and diaminoalkanes 2a–e (2 eq.) in absolute ethanol is heated under reflux for 16–22 h to afford 3a, b and 4a–c. Alternatively, under reaction conditions-B, a solution of thioamide 1 (1 eq.) in diaminoalkanes 2a–e (3 eq.) is stirred under solvent-free conditions at room temperature for 3 days to give desired products. Reaction conditions-A for having higher yields, shorter reaction times, and required less diamines is more effective than reaction conditions-B. Oxazolidine ring opening is observed by reacting compound 1 with all of the diamines 2a–e, but the thioamide group only reacts with nonbulky diamines 2a, b. The chemical structures of novel compounds were confirmed by 1H NMR, 13C NMR, elemental analysis, and FT-IR spectrometry.

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