SYNTHESIS OF NOVEL BI-FUNCTIONAL COPOLYMER BEARING STERICALLY HINDERED PHENOL AND HINDERED AMINE GROUPS VIA RING-OPENING METATHESIS POLYMERIZATION

Norbornene derivatives exo,endo-2-[2-(3,5-di-tert-butyl-4-hydroxyphenoxy)-acetoxy]methyl-5-norbornene(M1) and 3,3,5,5-tetramethyl-4-piperidinyl 5-norbornene-exo,endo-2-carboxylate(M2)were synthesized and polymerized by RuCl_2(=CHPh)(PCy_3)_2 to prepare a novel kind of bi-functional polymer bearing sterically hindered phenol(SHP)and hindered amine(HLAS)groups via ring-opening metathesis polymerization(ROMP).The resulting copolymers were characterized by gel permeation chromatography(GPC),~1H-NMR and differen...

Synthesis of New Polymer Ionomers via Ring-Opening Metathesis Polymerization

The N-pentafluorophenyl-exo-endo-norbornene-5,6-dicarboximide (2a) and N-phenyl-exo-endo-nor-bornene-5,6-dicarboximide (2b) monomers were synthesized and polymerized via ring-opening metathesis polymerization (ROMP) using bis(tricyclohexylphosphine) benzylidene ruthenium(IV) dichloride (I) and tricyclohexylphosphine [1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene][benzylidene] ruthenium dichloride (II). Both catalysts were used to synthesize random and block high molecular weight copolymers which were further hydrogenated using a Wilkinson’s catalyst. Then, the saturated copolymers were modified by reacting with sodium 4-hydroxybenzene-sulfonate dihydrate to generate new ionomers with fluoro-sulfonic acid pendant groups.

Synthesis,Structure,and Ring-opening Metathesis Polymerization of η~5-Pentamethylcyclopentadienyl-(η~5-exo-tricyclo [5.2.1.0^(2,6)]deca-2,5,8-trien-6-yl) Iron

η^5-Pentamethylcyclopentadienyl-（η^5-exo-tricyclo[5.2.1.0^2,6]deca-2,5,8-trien-6-yl） iron（3） was synthesized and characterized by ^1H NMR, ^13C NMR, MS, elemental analysis, IR, UV and X-ray diffraction analysis. Compound 3 was polymerized with ring-opening metathesis polymerization（ROMP） initiator （PCy3）2Cl2Ru=CHPh. ^1H NMR and IR spectra revealed the presence of CH=CH units in the polymer and supported the ROMP mechanism. GPC analysis of the polymer showed that the weight-average molecular weights（Mw） was 5967, and the polydispersity index（PDl） was 1.16. The polymer was also investigated by UV and cyclic voltammetry.

Ring-opening Metathesis Polymerization of Cis-5-norbornene-endo-2,3-dicarboxylic Anhydride Derivatives Using the Grubbs Third Generation Catalyst

A series of cis-5-norbornene-endo-2,3-dicarboxylic anhydride （NDCA, M1） derivatives （M2-M4） with different types of nonpolar substituted groups were synthesized and characterized by 1H/13C-NMR and mass spectrometry （MS）. Ring- opening metathesis polymerization （ROMP） of these monomers using the Grubbs third generation catalyst （G3） generated high molecular weight polymers with much improved solubility compared with the NDCA＇s homopolymer. It was found that the solubility of these polymers increased with increased substituent＇s steric hindrance. The living polymerization of NDCA derivative containing the bulkiest substituent （M4） catalyzed by G3 in tetrahydrofuran was confirmed by the kinetic studies with low polydispersity indices （PDI） （〈 1.30）. By using sequential ROMP, well-defined diblock copolymers containing anhydride groups were synthesized.

Ring-opening metathesis polymerization of cyclopropene derivatives towards polyolefin elastomer analogues

Polyolefin elastomers(POEs) are important reprocessable industrial materials with high strain-recovery performance. Traditional POEs are prepared from transition-metal-catalyzed polymerization of ethylene and α-olefins, while because of the complicated coordination polymerization mechanism, defining the actual distribution and length of alkyl branches in POEs is extremely challenging. We herein propose an alternative approach of synthesizing POE analogues from ring-opening metathesis polymerization(ROMP) of highly strained 3,3-alkyl-substituted cyclopropenes(CPEs). The structures of monomers and the substituents of Ru-catalysts are investigated in detail to evaluate the homobenzyl-substituted CPE derivative as a new living ROMP monomer. After copolymerization with cyclooctene and backbone hydrogenation, POE analogues with well-defined alkyl branches are prepared. Since the ROMP reactions have little isomerization and can also give good control of molecular weight and copolymer composition, it is hypothesized that this synthetic approach provides a novel platform to assist understanding the influence of branches on the properties of POEs.

(Arylimido)vanadium(V)-Alkylidene Complexes as Catalysts for Ring-opening Metathesis Polymerization(ROMP) of Cyclic Olefins: Ligand Design for Exhibiting the High Activity

(Imido)vanadium(V)-alkylidene complexes of type V(CHSiMe3)(NR)(OR?)(PMe3)2 [R = Ad, C6H5, 2,6-Me2C6H3, 2,6-Cl2C6H3;R?= 2,6-Me2C6H3, 2,6-i Pr2C6H3, 2,6-F2C6H3, C6F5, C6Cl5] exhibited from moderate to remarkable catalytic activities for ringopening metathesis polymerization(ROMP) of norbornene(NBE). The catalytic activities were affected by the ligand substituents, and V(CHSiMe3)(N-2,6-Cl2C6H3)(OC6X5)(PMe3)2(X = F, Cl) demonstrated the exceptionally high catalytic activities for ROMP of NBE.The complexes polymerized cycloheptene(CHPE) and cis-cyclooctene(COE), and ROMP of COE by the OC6 Cl5 analogue proceeded in a living manner even at 80℃, and the activity increased with increasing the temperature up to 120 ℃. Highly active catalysts for ROMP of cyclic olefins(NBE, cyclopentene, and CHPE) can be generated in situ by premixing isolated V(CHSiMe3)(NC6F5)(O-2,6-iPr2C6H3)(PMe3)2 with 1.0 equiv. of C6F5OH or C6Cl5OH via immediate phenoxy exchange;the activity was affected by the kind of phenol added [TOF in the ROMPs of NBE: 4.62 × 10^4 min^–1(upon addition of C6F5OH) versus 37.3 min^–1(none)].

Synthesis of Cyclic Polyolefin: Ring-Opening Metathesis Polymerization by Binuclear Vanadium Complexes

Ring-opening metathesis polymerization(ROMP)of norbornene by binuclear vanadium alkylidene in-situ formed from dialkyl complexes was investigated.Higher activities were observed by the binuclear system than mononuclear analogues.Especially the cyclic polymers were obtained and demonstrated.It is proposed that cyclic binuclear vanadium alkylidene was afforded due to the intramolecular chain-transfer reaction.The size of polymer ring could be adjusted by the vanadium catalyst structure and polymerization temperature.Similar results were also observed in the ROMP of cyclopentene.

Application of ring-opening metathesis polymerization in study of polymer molecular weight-mediated catalytic properties of immobilized lipase

Recently, significant efforts have been devoted into the study of the effect of hydrophobic supports on the catalytic properties of immobilized lipases. It seems that immobilization lipases on hydrophobic supports is a simple and efficient method to improve the catalytic activity of lipases. In this study, the hydrophobic poly(N-propyl-norbornene-exo-2,3-dicarboximide)s with well-controlled molecular weight were synthesized by the living ring-opening metathesis polymerization, and the lipases from Pseudo- monas sp. were then immobilized on these hydrophobic polymer supports through the physical ad- sorption. The immobilized lipases exhibited higher activity and enantioselectivity for the transesterifi- cation of 2-octanol than those of free lipases. Furthermore, we investigated the polymer molecular weight-mediated catalytic properties of immobilized lipases. It was found that the catalytic activity and E value of the immobilized lipases increased with the increase of the polymer molecular weight. At the polymeric molecular weight of about 40kDa, the highest E value (58 at 54.2% of conversion, enanti- omeric excess = 99%) was reached. After the molecular weight of polymers getting higher than 40 kDa, catalytic activity and E value of the immobilized lipase decreased.

From Polymerization Inhibition to Controlled Ring-Opening Metathesis Polymerization of Macromonomers with Tertiary Amine Groups:The Effect of Spacer Chain

Main observation and conclusion Ring-opening metathesis polymerization(ROMP)is a powerful toolbox in preparation of bottlebrush polymers for its high activity.However,the ROMP of macromonomers with repeating tertiary amine groups,for example,poly(2-(dimethylamino)ethyl methacrylate)(PDMAEMA).

RUTHENIUM CARBENE INITIATED RING-OPEN METATHESIS POLYMERIZATION OF ENDO-BICYCLO[3.2.0]HEPT-6-EN-3-YL BENZOATES WITH TACTICITY STUDIES

After tentative ring-opening cross metathesis （ROCM） of endo-bicyclo[3.2.0]hept-6-en-3-yl 4-bromobenzoate with PhCH = CH2 initiated by （Cy3P）2Cl2Ru = CHPh in CH2Cl2, ring-opening metathesis polymerization （ROMP） of a series of endo-bicyclo[3.2.0]hept-6-en-3-yl benzoates was achieved under the same conditions, furnishing a variety of the corresponding polymers. Then some of them were selected to hydrogenate the C=C double bonds in their backbone with p-tosylhydrazide, affording saturated and thus more flexible polymers. All of these polymers were well characterized by spectroscopic means including GPC, UV-Vis, NMR and IR, based on which the tacticity of these polymers was investigated together with nonlinear optical （electric-field-induced second-harmonic generation, EFISH）） analysis.

RING-OPENING POLYMERIZATION OF TRIMETHYLENE CARBONATE CATALYZED BY NOVEL SINGLE COMPONENT RARE EARTH CALIXARENE COMPLEXES

In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.

Ring-opening Polymerization ofε-Caprolactone Using Lanthanide Tris(4-tert-butylphenolate)s as a Single-component Initiator

The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.

RING-OPENING POLYMERIZATION OFε-CAPROLACTONE USING LANTHANIDE TRIS(N-PHENYL-3,5-DI-T-BUTYLSALICYLALDIMINATO)S AS SINGLE COMPONENT CATALYST

Ring-opening polymerization of ε-caprolactone has been carried out by using rare earth Schiff base complexes： lanthanide tris（N-phenyl-3,5-di-t-butylsalicylaldiminato）s [Ln（OPBS）3] as single component catalyst for the first time. The influences of different rare earth elements, monomer and catalyst concentration as well as reaction time on the polymerization were investigated. Mechanism studies showed that monomer inserts into the active site with the acyl-oxygen bond scission rather than the break of alkyl-oxygen bond.

SYNTHESIS, CHARACTERIZATION AND RING-OPENING POLYMERIZATION OF CYCLIC (ARYLENE PHOSPHONATE) OLIGOMERS

A series of cyclic (arylene phosphonate) oligomers were prepared by reaction of phenylphosphonic dichloride (PPD) with various bisphenols under pseudo-high dilution conditions via interfacial polycondensation. The yield of cyclic (arylene phosphonate) oligomers is over 85% by using hexadecyltrimethylammoniun bromide as phase transfer catalyst (PTC) at 0 'C . The structures of the cyclic oligomers were confirmed by a combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and IR analysis. These cyclic oligomers undergo facile ring-opening polymerization in the melt by using potassium 4,4'-biphenoxide as the initiator to give linear polyphosphonate. Free-radical ring-opening polymerization of cyclic(arylene phosphonate) oligomers containing sulfur linkages was also performed in the melt using 2,2'-dithiobis(benzothiazole) (DTB) as the initiator at 270 °C and the resulting polymer had a Mw, of 8 × 103 with a molecular weight distribution of 4. Ring-opening copolymerization of these cyclic oligomers with cyclic carbonate oligomers was also achieved. The average molecular weight of the resulting copolymer is higher than the corresponding homopolymer and the thermal stability of the copolymer is better than the corresponding homopolymer.

SYNTHESIS OF POLY(5,5-DIMETHYL-1,3-DIOXAN-2-ONE)BY LIPASE-CATALYZED RING-OPENING POLYMERIZATION

Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads wereemployed successfully for the ring-opening polymerization of 5, 5-dimethyl-1, 3-dioxan-2-one (DTC) for the first time.Different polymerization conditions such as enzyme concentration and reaction temperature were studied. Immobilized PPLexhibits higher activity than native PPL. Along wth the increasing enzyme concentration, the molecular weigh of resultingPDTC decreases. PPL immobilized on narrow distributed micron-sized glass beads has outstanding recyclability. For thethird recycle time, immobilized PPL exhibits the highest catalytic activity and with high activity even after the fifth recyletime for the synthesis of PDTC. The ~1H-NMR spectra indicate that decarboxylation does not occur during the ring-openingpolymerization.

A Series of Rare Earth Phenolates Substituted by Alkyl Groups for D,L-Lactide Ring-Opening Polymerization

Single component rare earth phenolates substituted by various alkyl groups have been prepared and the correlation between the aryloxides＇ structure and catalytic activity in the ring-opening polymerization of D,L-lactide has also been investigated.The catalytic activity of all rare earth aryloxides,characteristics of the ring-opening polymerization as well as polymerization kinetics and mechanism were investigated.The results showed that both phenolates＇ catalytic activities and polymerization characteristics changed regularly,keeping in good concordance with variations in substitutents＇ number on phenol and structure of aryloxide ligands.The stronger ability of electron-donation of alkyl groups,the higher catalytic activity.Moreover,the more numbers of substituted alkyl on phenyl ring,the higher catalytic activity.The analyses of polymer ends revealed that the polymerization proceeded via a coordination-acyl-oxygen bond cleavage-insertion mechanism.

Tetrahydrosalen backboned gadolinium complex as initiator for the ring-opening polymerization of ε-caprolactone

Tetrahydrosalen ligand was employed in the synthesis of gadolinium complex. The ligand was deprotoned by LiBu, and the afforded lithium salt was reacted with anhydrous GdCl3 to produce the gadolinium complex through salt metathesis. This complex was successfully used to initiate the ring-opening polymerization of ε-caprolactone. The initiation conditions in different temperature, monomer-to-initiator ratio and time were investigated. Under the condition： [ε-caprolactone]：[catalyst] = 600, 56 ℃, toluene： 2 ml, poly（ε-caprolactone） （PCL） with Mw = 11,2782 and PDI = 1.96 was achieved.

RING-OPENING POLYMERIZATION OF TRIMETHYLENE CARBONATE BY CALIX[8]ARENE-NEODYMIUM

Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2,000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.

Cationic ring-opening polymerization of 3,3-bis(chloromethyl)oxacyclobutane in ionic liquids

Cationic ring-opening polymerization of 3,3-bis（chloromethyl）oxacyclobutane catalyzed by BF3.OEt2 was carded out in ionic liquids [bmim]BF4 and [bmim]PF6. The influences of BCMO concentration and molar ratio of BCMO/BF3.OEt2 on the molecular weights and yield of PBCMO were investigated. The polymerization in ionic liquids proceed to high conversions, although molecular weights are limited, similar to polymerization in organic solvent such as CH2Cl2. Follow a viewpoint of green chemistry, we feel ionic liquid [bmim]BF4 is superior to [bmim]PF6. Extracting [bmim]PF6 from the product using organic solvent as extractant limits its advantage as a green reaction media.