Synthesis, Crystal Structure of [(MeC_5H_4)_2Ln(μ-OCH_2CH_2NMe_2)]_2 (Ln=Sm, Y, Nd) and Their Catalytic Activity for Ring-Opening Polymerization of ε-Caprolactone

Reaction of (MeC 5H 4) 3Ln with HOCH 2CH 2NMe 2 in tetrahydrofuran(THF) gives the new complexes [(MeC 5H 4) 2Ln(μ OCH 2CH 2NMe 2)] 2 (Ln=Sm, Y, Nd) with nitrogen functionalized μ alkoxide ligand. The complexes were characterized by elemental analysis and IR, and [(MeC 5H 4) 2Sm(μ OCH 2CH 2NMe 2)] 2 was structurally characterized by the X ray diffraction to be a dimer formed by two unsymmetric oxygen bridges. The complex has a tricyclic skeleton with the additional two Sm-N bonds via intramolecular coordination of OCH 2CH 2NMe 2. The coordination number of the central metal Sm is nine. The title complexes show good catalytic activity for ring opening polymerization of ε caprolactone.

CATIONIC RING-OPENING POLYMERIZATION OF TETRAHYDROFURAN WITH KEGGIN-TYPE HETEROPOLYCOMPOUNDS AS SOLID ACID CATALYSTS

Three Keggin-type heteropolyanions, namely H3PMo12O40-13H2O, （NH4）3PMo12O40·4H2O and H3PW12O40·13H2O were prepared and tested in the ring-opening polymerization reaction of tetrahydrofuran. The effects of the counter-cation （H＋, NH4＋） and the peripheral atoms （Mo, W） on the polymerization were investigated. It has been found that when the protons of H3PMo12O40·13H2O were replaced by the ammonium cations the polymerization rate decreased dramatically. Whereas, when the peripheral atoms （Mo） were replaced by their homologous （W）, the polymerization rate increased twofold. As for the viscosity average molecular weight （My） of polymer products, it was found that the high molecular weight （7930） was obtained by using H3PW12O40·13H2O. The molecular weight （My） obtained by H3PMo12O40·13H2O and （NH4）H3PMo12O40·13H2O was 6470 and 6810, respectively.

Polycaprolactone (PCL) Chains Grafting on the Surface of Cellulose Nanocrystals (CNCs) during <i>In Situ</i>Polymerization of <i>ε</i>-Caprolactone at Room Temperature

This work aimed at investigating the feasibility of surface modification of cellulose nanocrystals (CNCs) using in situ ring opening polymerization of ε-caprolactone (ε-CL) at room temperature. Residues of flax and milkweed (Asclepias syriaca) stem fibers were used as a source of cellulose to obtain and isolate CNCs. The cationic ring opening polymerization (CROP) of the monomer ε-CL was used to covalently graft polycaprolactone (PCL) chains at the CNCs surface. Silver hexafluoroantimonate (AgSbF6) was used in combination with the extracted CNCs to initiate, at room temperature, the polymerization and the grafting reactions with no other stimulus. Fourier-Transform InfraRed (FTIR), X-ray Photoelectron Spectrometry (XPS), UV/visible absorption and Gel Permeation Chromatography (GPC) analyses evidenced the presence of PCL chains covalently grafted at CNCs surface, the formation of Ag(0) particles as well as low or moderate molecular weight free PCL chains.

SYNTHESIS AND POLYMERIZATION OF 2-OXO-3-METHYLENE-5, 6-DIPHENYL-1,4-DIOXAN

A new cyclic monomer, 2-oxo-3-methylene-5, 6-diphenyl-1, 4-dioxan, was synthesized. Thestructure of the intermediates and the monomer were determined by IR,~1H NMR,^(13)C NMR andelemental analysis. This new monomer is different from other cyclic monomers in this series,it isa solid (mp 108--109℃)and not very reactive, but still can undergo free radical ring-openingpolymerization. The free radical polymerization was carried out at 130℃. The structure of theresulting polymer was discussed and charaterized by IR, ~1H NMR, ^(13)C NMR and elementalanalysis. The molecular weight of the polymer was estimated by viscosity determination.

SYNTHESIS AND ANIONIC POLYMERIZATION OF 2-METHYL-2-METHOXY CARBONYL-5-METHYLENE-1, 3-DIOXOLAN-4-ONE

A new cyclic monomer, 2-methyl-2-methocycarbonyl-5-methylene 1,3-dioxlan-4-one,wassynthesized successfully. The monomer and intermediate were characterized by ~1H NMR,^(13)C NMR, INEPT (Intensive Nuclei Enhanced by Polarization Transfer) technique, IR andelemental analysis. Anionic polymerization of the monomer was carried out in anhydrous THF at.70℃, and 9-fluorenyllithium was used as initiator. The polymer strucure was determined byIR, NMR and elemental analysis. Molecular weight of the polymer was estimated by viscositymeasurement in DMSO at 30℃.

SYTHESIS AND ANIONIC POLYMERIZATION OF 2-METHYL-2-METHOXYCARBONYL-5-METHYLENE-1, 3-DIOXOLAN-4-ONE

A new cyclic monomer, 2-methyl-2-methoxycarbonyl-5-methylene-1,3-dioxolan-4-one,was synthesized successfully. The monomer and intermediate were characterized by ~1H NMR, ^(13)CNMR, INEPT(Intensive Nuclei Enhanced by Polarization Transfer) technique, IR and elementalanalysis. Anionic polymerization of the monomer was carried out in anhydrous THF at -70℃,and 9-fluorenyllithium was used as initiator. The polymer structure was determined by IR, NMRand elemental analysis. Molecular weight of the polymer was estimated by viscosity measurementin DMSO at 30℃.

SYNTHESIS AND FREE RADICAL POLYMERIZATION OF 2-OXO-3-METHYLEN E-5-PHENYL-1,4-DIOXAN

The novel cyclic monomer, 2-oxo-3-methylene-5-phenyl-1,4-dioxan, was synthesized by a set of reactions. Several intermediates were prepared and characterized in order to determine the monomer structure. The presence of chiral centers in the intermediates and resulting monomer makes it complicated to separate , purify and characterize them. It is a very reactive monomer which will polymerize even at room temperature if expose to moisture and air. This monomer can undergo essentially quantitative flee radical ring opening polymerization. The driving force for ring opening is the formation of new carbonyl group and benzylic radical. The monomer and polymer structure were established by IR, ~1H NMR, ^(13)C NMR and elemental analysis or high resolution mass spectrum. The molecular weight of the resulting polymer was estimated by viscosity determination.

SYNTHESIS OF POLY(GLUTAMIC ACID-co-ASPARTIC ACID) VIA COMBINATION OF N-CARBOXYANHYDRIDE RING OPENING POLYMERIZATION WITH DEBENZYLATION

The random copolymers of glutamic acid （LG） and aspartic acid （ASP）, poly（LG-co-ASP）, with designed compositions could be successfully synthesized via combination of N-carboxyanhydride ring opening copolymerization with debenzylation. Ring opening copolymerizations of y：benzyl-L-glutamate N-carboxyanhydride （BLG-NCA） and β-benzyl-Laspartate N-carboxyanhydride （BLA-NCA） were carried out by using different amines including triethylamine （TEA）, diethylamine, n-hexylamine （NHA）, triphenylamine, diphenylamine or aniline as initiators. All the 6 amines were highly efficient to get well-defined poly（BLG-co-BLA） copolymers with designed compositions although the polymerizations proceeded via different mechanisms （normal amine mechanism or/and activated monomer mechanism）, which are based on chemical structure of amines. The molecular weights of poly（BLG-co-BLA） copolymers could be mediated by both TEA concentration and polymerization time. Then, debenzylation ofpoly（BLG-co-BLA） copolymers was conducted to prepare the corresponding hydrophilic random eopolymers of poly（LG-co-ASP） with a-subunit structure in ASP structural units. The contents of LG structural units in poly（LG-co-ASP） copolymers matched with those of BLG-NCA in NCA-monomer feeds in ring opening copolymerizations initiated by NHA or TEA and were closed to the theoretical line. The diblock copolymer of poly（BLG-b-BLA） could also be synthesized via living NCA ring opening copolymerization by sequential addition of BLG- NCA and BLA-NCA.

Recent Advances in the Synthesis and Polymerization of New CO_(2)-Based Cyclic

Carbon dioxide can be converted into functional heterocycles known as cyclic carbonates,whose recent reactivity has been expanded towards the formation of tailor-made engineering polymers.This minireview gives an overview of the most topical developments in this area with a special focus on the synthetic methods employed to prepare these CO_(2)based synthons.In addition,their application potential in the area of polymer science using a variety of polymerization techniques is discussed that have in common the ring-opening of the carbonate monomers.Future perspectives are provided that provide impetus for the scientific communities aligning research to the use of sustainable processes for polymers from recyclable carbon sources such as CO_(2).

Synthesis of Benzoxazine Functionalized Amine-Bridged Bis(phenolato) Rare Earth Complexes and Their Application in Ring-Opening Polymerization of rac-Lactide

The reactivities of benzoxazine functionalized amine bridged bis(phenol)s LnH_(2)(n=1—3)with rare earth metal complexes were explored,founding that both the aryl substituents of the ligand and the rare earth metals have profound influences on reaction outcomes.

RING OPENING POLYMERIZATION OF TETRAHYDROFURAN CATALYSED BY MAGHNITE-H^+

The cationic ring-opening polymerization of tetrahydrofiiran using maghnite-H~＋ is reported.Maghnite-H~＋,is a non-toxic solid catalyst issued from proton exchanged montmorillonite clay.Polytetrahydrofuran,also called ＂poly（butandiol） ether＂,with acetate and hydroxyl end groups was successfully synthesized.Effects of reaction temperature, weight ratio of initiator/monomer and reaction time on the conversion of monomer and on the molecular weight are investigated.A cationic mechanism of the reaction was proposed.This chemistry can be considered as a suitable route for preparing poly（THF） as a soft segment for thermoplastic elastomers.

Synthesis of Poly(Glycolide-CO-2-hydro-2-oxo-1,3,2-Dioxaphosphorinane)

A novel polyester containing glycolic acid(GA)and 2 hydro 2 oxo 1,3,2 dioxaphosphorinane(TMP)was prepared by ring opening polymerization.The composition and the structure of the titled polymer were investigated by 1H NMR, 13 C NMR,FT IR,EA,and VPO.The influence of time on total conversion and molecular weight was also studied.

Syntheses of Novel Macrocyclic Polyarylate Oligomers Based on Phenolphthalein and m-Phthaloyl dichloride

Novel macrocyclic oligomers were synthesized through the condensation of phenolphthalein and m phthaloyl dichloride with triethylamine as catalyst in the mixed solution of methylene chloride and THF via pseudo high dilution technique. The oligomers were characterized by IR, 1H NMR , MS, WAXD, TGA and DSC. It was found that the 3∶3 adduct(molar ratio of phenolphthalein to m phthaloyl dichloride) and the 4∶4 adduct were the main products and there was a small amount of crystalline in the macrocyclic mixtures. When the mixtures were heated to 360 ℃ , the crystalline disappeared.

Enzymatic Synthesis and Characterization of Novel Polycarbonates Derived from 5-Allyloxy-1, 3-dioxan-2-one and 5, 5-Dimethvl-1.3-dioxan-2-one

Novel polycarbonates from 5-allyloxy-1, 3-dioxan-2-one （ATMC） with 5, 5-dimethyl- 1, 3-dioxan-2-one （DTC） were successfully synthesized for the first time using immobilized porcine pancreas lipase （IPPL） as catalyst. The resulting copolymers were characterized by IR, ^1H NMR, ^13C NMR and GPC. The molecular weight （Mn） of the copolymer with molar feed ratio of 10：90 （ATMC：DTC） was 9300 and the polydispersity was 1.31, while the Mn increased to 14300 and polydispersity of 1.25 with the feed ratio of 50：50. Moreover, the composition of the copolymers agreed well with the monomer feed.

Performance Comparison of Commercial and Home-Made Lipases for Synthesis of Poly(δ-Valerolactone)Homopolymers

Novozyme 435,which is the commercially available immobilized form of Candida antarctica lipase B,has been successfully conducted ring opening polymerization of lactones in organic solvents.In this paper,it was aimed to introduce an alternative biocatalyst for Novozyme 435.Candida antarctica lipase B immobilized onto rice husk ashes via physical adsorption(with a specific activity of 4.4 U/mg)was prepared in previous studies and used as a biocatalyst for poly(δ-valerolactone)synthesis in the present work.Polymerization reactions were proceeded at various reaction temperatures and periods via both two immobilized enzyme preparations.The resulting products were characterized spectroscopically and thermally.The highest molecular weight(Mn=9010 g/mol)was obtained via Novozyme 435 catalysis at 40℃and 24 hours.The performance of home-made lipase,which resulted in a molecular weight of 8040 g/mol,was close to commercial one.

Synthesis and Characterization of Lactone Functional Macromonomers by End Group Deactivation and Their Use in Miktoarm Star Polymer

Newly designed miktoarm star-shaped copolymers made of poly[(benzyl methacrylate(BMA)-co-(ε-caprolacton)(CL)] and poly[(BMA-b-MMA-b-BMA)-co-ε-caprolacton)(CL)] were synthesized by combining ring-opening polymerization (ROP) of ε-caprolactone (CL) and poly(BMA) five membered lacton fuctionalized prepared via atom transfer radical polymerization (ATRP) of BMA, and ε-CL and P(BMA-b-MMA-b-BMA) dual functionalized diblock copolymer, in the presence of tin(II) bis(2-ethylhexanoate) (Sn(Oct)2). Although lactone ended poly(benzyl methacrylate) with ε-caprolactone monomer gave ring open polymerization by Sn(Oct)2, the macromonomer itself did not give any poly- merization The macromonomers, and the miktoarm star-shaped copolymers were analyzed by FT-IR and 1H-NMR spectroscopies and GPC (gel permeation chromatograph), Differential scanning calorimetry (DSC-50) and termo- gravimetric analysis (TGA-50). These copolymers exhibited the expected structure. The crystallization of star-shaped copolymers was studied by DSC. The results show that when the content of the BMA block increased, the Tm of the star-shaped block copolymer increased.

EFFECTS OF MOLECULAR WEIGHT ON THERMAL RESPONSIVE PROPERTY OF PEGYLATED POLY-L-GLUTAMATES

We investigated the ring opening polymerization （ROP） of di- and tri-ethylene glycol monomethyl ether functionalized L-glutamate N-carboxyanhydrides （NCAs） using hexamethyldisilazane （HMDS） as primary initiator and 1,5,7-triazabicyclo-[4.4.0]dec-5-ene （TBD） as co-initiator. The binary initiator system afforded a living ROP for these pegylated NCAs, and a series of homopolypeptides with controlled molecular weight （MW） and low polydispersity were obtained. We then systematically studied the helical content and clouding point （CP） dependence on polypeptide MW using circular dichroism （CD） spectroscopy and turbidity measurements, respectively. We found that the helical content of both homopolypeptides increased with MW, but the triethylene glycol functionalized poly-L-glutamate （poly-L-EG3Glu） intended to form more stable or-helical structure than diethylene glycol functionalized counterpart （poly-L-EG2Glu） at similar MW. Accordingly, the CP of poly-L-EG2Glu with known end group has strong dependence on its helical content, which is essentially determined by MW. Our results suggested that the thermal responsive properties of these unique pegylated poly- L-glutamates not only rely on their chemical structure but also on their secondary structures, wh^ch is different from conventional thermal responsive polymers.

Synthesis and Characterization of Nano Ag End Capped L-Cysteine Bridged Diblock Copolymer

The target of the present investigation is synthesis and characterization of an amphiphilic diblock copolymer with antibacterial property. Ring opening polymerization （ROP） of ε-caprolactone （CL） and tetrahydrofuran （THF） was carried out under inert atmosphere by using L-cysteine as a bridging agent in the presence of stannous octoate （SO） as a catalyst. The nano silver end capped diblock copolymer was synthesized by in situ method. Thus obtained nano silver end capped L-cysteine bridged diblock copolymer was characterized by various analytical methods like Fourier transform infrared （FTIR） spectroscopy, nuclear magnetic resonance （NMR） spectroscopy, circular dichroism （CD）, fluorescence spectroscopy, gel permeation chromatography （GPC）, X-ray photoelectron spectroscopy （XPS）, thermogravimetric analysis （TGA）, differential scanning calorimetry （DSC）, field emission scanning electron microscopy （FESEM）, high resolution transmission electron microscopy （HRTEM） and zeta potential. The antimicrobial property of the nano silver end capped diblock copolymer against e-coli was tested.