Synthesis and Characterization of Poly (L-Lactic acid) Containing the Azobenzene Mesogens

2011 ◽  
Vol 181-182 ◽  
pp. 185-188
Author(s):  
Run Tao Dong ◽  
Qing Bin Xue ◽  
Ling Min Sun ◽  
Quan Xuan Zhang
Keyword(s):  
Lactic Acid ◽  
Optical Rotation ◽  
Gel Permeation Chromatography ◽  
Helical Structure ◽  
Feed Ratio ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
H Nmr ◽  
Azobenzene Mesogens

A series of azobenzene containing group Poly (L-lactic acid) (PLLA) were synthesized by Ring-Opening Polymerization of L-lactide (L-LA) catalysted by Sn (Oct)2initiated by alcohol-OH containing the azobenzene chromophores. Their molecular weights were well controlled by the feed ratio as characterized by Gel Permeation Chromatography (GPC) and1H NMR Spectrometry and agreed well with theoretical values. The thermal properties and liquid crystal phases were investigated by Differential Scanning Calorimetry (DSC), polarized optical microscopy (POM) and X-ray Diffraction (XRS) measurements. Cis-trans photoisomerization behavior of the polymers in the solutions and the films were studied with UV irradiation. By the Circular Dichroism Spectroscopy (CD) characterization of the solutions and films of the polymer, the PLLA segments show huge optical rotation power in helical structure.

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.

scholarly journals Environmental Profile and Technological Validation of New High-Tg Unsaturated Polyesters from Fully Bio-Based Monomers and Reactive Diluents

2020 ◽  
Author(s):  
Raffaella Suriano ◽  
Maria Nelly Garcia Gonzalez ◽  
Stefano Turri
Keyword(s):  
Unsaturated Polyester ◽  
Gel Permeation Chromatography ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Positive Effects ◽  
Reactive Diluents ◽  
Composite Polymers ◽  
Category Indicator ◽  
Monomer Feed

Abstract This study was focused on the synthesis and characterization of a fully bio-based unsaturated polyester resin (UPR) with good thermal properties suitable for the commercial production of composite polymers. UPRs based on different ratios of bio-based furan dicarboxylic acid (FDCA), itaconic acid, and diols were synthesized. The unsaturated polymers prepared were evaluated by differential scanning calorimetry, gel permeation chromatography, FTIR and 1H-NMR spectroscopy. The results showed positive effects of FDCA on the glass transition temperature (Tg) of these fully bio-based polyesters, especially when FDCA was combined with 1,2-propanediol. Optimal values of Tg were obtained in the range of 30–32 °C for UPRs synthesized starting with a higher concentration of FDCA in the monomer feed. The possibility of substituting styrene, which usually acts as a reactive diluent, with a greener and safer alternative during the crosslinking of UPRs, was also explored. Two bio-based reactive diluents were considered: dimethyl itaconate (DMI) and butanediol dimethacrylate. After crosslinking, an average Tg of 75 °C and a good crosslinking efficiency indicated by a gel content of 90% were achieved for the fully bio-based polyester obtained under milder reaction conditions and dilution with DMI. Life cycle assessment was performed on selected UPRs, and comparison with a reference fossil-based resin in terms of the calculated category indicator results confirmed the lower environmental impact of the newly prepared bio-based polyesters.

Synthesis and Characterization of Polyacrylates Side-Chain Liquid Crystalline Polymer via Atom Transfer Radical Polymerization

2012 ◽  
Vol 535-537 ◽  
pp. 1516-1519
Author(s):  
Ying Gang Jia ◽  
Peng Tian ◽  
Kun Ming Song ◽  
Bao Yan Zhang
Keyword(s):  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Liquid Crystalline ◽  
Gel Permeation Chromatography ◽  
Crystalline Polymer ◽  
Atom Transfer ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
H Nmr

Atom transfer radical polymerization (ATRP) of methacrylate liquid crystal monomer M (4-((4-(2-(acryloyloxy)ethoxy)benzoyl)oxy)phenyl 4-propylbenzoate) was carried out using CuBr/PMDETA complex as catalyst and 2-bromo-2-methyl-propionic acid ester as initiator. The obtained monomer M and polymer P was characterized via infrared spectroscopy and1H NMR. The phase behavior and mesomorphism were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and x-ray diffraction (XRD). The molecular weight and the structure of the polymers were identified with gel permeation chromatography and nuclear magnetic resonance.

Synthesis and property studies of oligomer obtained from the reaction of 4-vinylbenzocyclobutene and styrene with divinyl tetramethyl disiloxane-bisbenzocyclobutene

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Yewei Xu ◽  
Fanghua Zhu ◽  
Liqin Xie ◽  
Junxiao Yang ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Low Cost ◽  
Gel Permeation Chromatography ◽  
Radical Copolymerization ◽  
Film Material ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Good Thermal Stability ◽  
Molecular Weights ◽  
H Nmr ◽  
Polymer Resin

AbstractRadical copolymerization of 4-vinylbenzocyclobutene (VBCB) with styrene (St) afforded the copolymer (4-vinylbenzocyclobutene-co-styrene) (VBCBSt). Reaction of VBCB-St and divinyl tetramethyl disiloxane-bisbenzocyclobutene (DVSBCB) gave the oligomer (VBCB-St-DVSBCB), which was subsequently subjected to the cure reaction. The structures of VBCB-St and oligomer (VBCB-St- DVSBCB) were characterized by FTIR and 1H NMR, which are in agreement with the proposed structures. Molecular weights of the synthesized polymers were estimated by gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) showed that VBCB-St exhibited glass transition temperature (Tg > 95 °C) however it is not the case for the oligomers (VBCB-St-DVSBCB). TG measurements indicated that the polymers had the good thermal stability with decomposition temperatures (TD > 370 °C). The polymer resin possessed good film planarization in the AFM images and the process of oligomer curing on a wafer without fusion and flow. These results indicated that the oligomer (VBCB-St- DVSBCB) is a promising film material with a relatively low cost.

Synthesis and characterization of 4- and 6-arm star-shaped poly(ε-caprolactone)s

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Michael A. R. Meier ◽  
Ulrich S. Schubert
Keyword(s):  
Ring Opening ◽  
Analytical Techniques ◽  
Gel Permeation Chromatography ◽  
Laser Desorption ◽  
Ring Opening Polymerization ◽  
Molecular Weights ◽  
H Nmr ◽  
Flight Mass Spectrometry ◽  
Gel Permeation

AbstractStar-shaped poly(ε-caprolactone) (PCL) polymers were synthesized and fully characterized by gel permeation chromatography, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) as well as 1H NMR spectroscopy. First a series of four-armed PCLs with different molecular weights was prepared and analyzed with the mentioned analytical techniques revealing that the applied ring-opening polymerization was controlled and defined star-shaped polymers could be synthesized. Subsequently, also the synthesis of six-armed PCL polymers was investigated with the conclusion that also these starshaped polymers could be prepared in a controlled fashion.

Synthesis and characterization of 4-chloromethylstyrene polymers containing bulky organosilicon groups

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Kazem Dindar Safa ◽  
Mirzaagha Babazadeh
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Gel Permeation Chromatography ◽  
Synthesis And Characterization ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Gel Permeation ◽  
Covalently Linked ◽  
C Nmr

Abstract The homopolymer of 4-chloromethylstyrene and its copolymers with styrene (in 1:3 and 1:1 mole ratio) were synthesized by bulk and solution freeradical polymerisations, respectively, at 70±1°C using α,α'-azoisobutyronitrile as an initiator. Highly sterically hindered tris(trimethylsilyl)methyl (Tsi) substituents were then covalently linked to the obtained homopolymer and copolymers. The polymers were characterized by IR, 1H NMR and 13C NMR, differential scanning calorimetry (DSC) and gel permeation chromatography. DSC showed that incorporation of Tsi substituents in the side chains of homopolymer and copolymers increases the rigidity of the polymers and, subsequently, their glass transition temperature.

scholarly journals Synthesis and characterization of alternating poly(amide urea)s and poly(amide urethane urethane)s from ε-caprolactam, diamines, and diphenyl carbonate or ethylene carbonate

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Luc Ubaghs ◽  
Bhaskar Sharma ◽  
Helmut Keul ◽  
Hartwig Höcker ◽  
Ton Loontjens ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Nmr Spectroscopy ◽  
Ethylene Carbonate ◽  
Building Blocks ◽  
Diphenyl Carbonate ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
H Nmr ◽  
End Groups

Abstract Alternating poly(amide urea)s from ε-caprolactam, diamines H2N-(CH2)x- NH2 (x = 2 - 4), and diphenyl carbonate were prepared in two steps. The microstructure of the poly(amide urea)s, as determined by means of 1H NMR spectroscopy, reveals a strictly alternating sequence of the building blocks. The molecular weights and polydispersities obtained were 7500 < Mn < 10 000 and 1.48 < Mw/Mn < 1.56, respectively. Thermal properties were determined by means of differential scanning calorimetry (DSC) (163.9°C < Tm < 197.2°C; 55.5°C < Tg (2nd heating) < 72.2°C), and thermogravimetric analysis (TGA). TGA shows a three-step decomposition at 200, 350, and 450°C, which was attributed to the cleavage of O-phenyl urethane end groups, as well as urea and amide linkages. These assignments were made by comparison with model compounds. Furthermore, alternating poly- (amide urethane urethane)s from ε-caprolactam, diamines, and ethylene carbonate were prepared in three steps. The microstructure of the poly(amide urethane urethane)s, as determined by means of 1H NMR spectroscopy, reveals imperfections. The molecular weights and polydispersities obtained were 5400 < Mn < 17 000 and 2.08 < Mw/Mn < 2.99, respectively. Thermal properties were determined by means of DSC (155.9°C < Tm < 159.0°C; 35.5°C < Tg (2nd heating) < 39.0°C) and TGA. TGA shows a complex decomposition due to the formation of ethylene carbonate by cleavage of the urethane groups (at approx. 230°C) and formation of poly(amide urea)s. The newly formed poly(amide urea)s decompose in a similar way as the poly(amide urea)s.

Melt Polycondensation and Analysis of Hydroxyl-Terminated Poly(L-lactic Acid) Using Small Molecular Diols as Terminating Agents

2013 ◽  
Vol 328 ◽  
pp. 890-894
Author(s):  
Jing Che ◽  
Rong Jie Yang
Keyword(s):  
Lactic Acid ◽  
Ethylene Glycol ◽  
Gel Permeation Chromatography ◽  
Catalyst System ◽  
Molecular Weights ◽  
H Nmr ◽  
Melt Polycondensation ◽  
Direct Melt Polycondensation ◽  
Group Structures ◽  
End Group

The synthesis of hydroxyl-terminated poly (L-lactic acid) (PLLA) by direct melt polycondensation of L-lactic acid and use of small molecular diols as terminating agents was investigated. L-lactic acid was dewatered to prepare the dehydrated prepolymer at first. Then PLLA was prepared through melt polycondensation in a melt with catalyst system including TSA, SnCl2and Sn (Oct)2. Finally, ethylene glycol, 1,4-butanediol, and 1,8-octanediol, respectively, were used in hydroxyl termination of the PLLA. The molecular weights and end-group structures of all products were characterized by gel permeation chromatography (GPC) and1H-NMR. DSC and Disc Polarimeter were used to characterize crystallinity and racemization, respectively. The results show that two kinds of hydroxyl-terminated PLLA polymers were obtained: complete hydroxyl-terminated PLLA prepared by using ethylene glycol or 1,4-butanediol, incomplete hydroxyl-terminated PLLA prepared by using 1,8-octanediol or combination of two kinds of diols. Combination of ethylene glycol or 1,4-butanediol with 1,8-octanediol can reach high hydroxyl termination of PLLA, and maintain the molecular weight by decrease of alcoholysis at the same time.1H-NMR was found as an effective estimating way for extents of reactions. The hydroxyl-terminating reactions of PLLA by the diols reduced the crystallinity and resulted in racemization to some extent.

scholarly journals Preparation, Mechanical, and Thermal Properties of Biodegradable Polyesters/Poly(Lactic Acid) Blends

2010 ◽  
Vol 2010 ◽  
pp. 1-8 ◽  
Author(s):  
Peng Zhao ◽  
Wanqiang Liu ◽  
Qingsheng Wu ◽  
Jie Ren
Keyword(s):  
Lactic Acid ◽  
Gel Permeation Chromatography ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Butylene Succinate ◽  
Biodegradable Polyesters ◽  
H Nmr ◽  
Melt Polycondensation ◽  
Twin Screw

Series of biodegradable polyesters poly(butylene adipate) (PBA), poly(butylene succinate) (PBS), and poly(butylene adipate-co-butylene terephthalate) (PBAT) were synthesized successfully by melt polycondensation. The polyesters were characterized by Fourier transform infrared spectroscopy (FTIR),1H-NMR, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC), respectively. The blends of poly(lactic acid) (PLA) and biodegradable polyester were prepared using a twin screw extruder. PBAT, PBS, or PBA can be homogenously dispersed in PLA matrix at a low content (5–20 wt%), yielding the blends with much higher elongation at break than homo-PLA. DSC analysis shows that the isothermal and nonisothermal crystallizabilities of PLA component are promoted in the presence of a small amount of PBAT.

scholarly journals Synthesis and characterization of poly [N-acryloyl-(D/L), (+/−)-phenylalanine-co-(D/L), (−/+)N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea)] copolymers

2014 ◽  
Vol 12 (10) ◽  
pp. 1056-1066 ◽  
Author(s):  
Emil Buruiana ◽  
Mioara Murariu ◽  
Tinca Buruiana
Keyword(s):  
Optical Rotation ◽  
Molar Fraction ◽  
Fluorescein Isothiocyanate ◽  
Gel Permeation Chromatography ◽  
2D Nmr ◽  
Optically Active ◽  
Scanning Calorimetry ◽  
Ph Measurements ◽  
Ft Ir

AbstractTwo monomers of (D/L), (+/−)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea) methacrylate (D/L-MABU) type were prepared and further polymerized through free radical polymerization with optically active monomers containing phenylalanine sequences such as N-acryloyl-(D/L), (−/+)-phenylalanine (A-D/L-Phe). The resulting copolymers, i.e., poly[N-acryloyl-(D/L), (−/+)-phenylalanine-co-(D/L), (+/−)-N-methacryloyloxyethyl-N′-2-hydroxybutyl(urea)], A-D/L-Phe-co-D/L-MABU, were characterized by FT-IR, 1D/2D NMR (1H and 13C), UV-vis, and circular dichroism (CD) spectroscopies, differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The copolymers obtained with a molar fraction of 0.76: 0.24 / 0.64: 0.36 monomer units had optical rotation values of −25° and +15°, respectively. Upon chemical modification of the phenylalanine-based copolymers with fluorescein-isothiocyanate, new fluorescent copolyacrylates (A-D/L-Phe-co-D/L-MABU-F) were synthesized and further studied for pH measurements in DMF solutions using HCl and NaOH 10−1M. It was found that sterioselectivity of the A-L-Phe-co-L-MABU-F copolymer is higher than of its dextro-form, especially at basic pH.

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