三亚甲基环碳酸酯及2,2-二甲基三亚甲基环碳酸酯开环均聚合*

生物降解聚合物聚三亚甲基环碳酸酯（PTMC）及聚2,2-二甲基三亚甲基环碳酸酯（PDTC）在药物控释载体及其它生物医学技术领域有着良好的应用前景。与脂肪族聚酯不同,PTMC、PDTC降解时,不会产生有害的酸性化合物。PTMC、PDTC主要由三亚甲基环碳酸酯（TMC）及2,2-二甲基三亚甲基环碳酸酯（DTC）开环均聚合制备。本文总结了催化TMC、DTC开环均聚合的不同催化剂及其聚合机理,综述了近年来国内外在TMC、DTC均聚合催化剂开发上的研究进展,并对生物相容性催化剂如稀土催化剂、Ca、Mg、Zn、Fe催化剂以及酶催化剂催化TMC、DTC开环聚合的优缺点进行了比较。     

Ring-opening polymerization of 2,2-dimethyltrimethylene carbonate using rare earth aryl oxides substituted by alkyl groups

Single component rare earth aryl oxides substituted by various alkyl groups [Ln(OAr)3] such as methyl,isopropyl,and tertbutyl have been developed to initiate the ring-opening polymerization of 2,2-dimethyltrimethylene carbonate(DTC).The catalytic activity of rare earth aryl oxides,characteristics of the ring-opening polymerization as well as the polymerization kinetics and mechanism were intensively examined.The experimental results turn out that the catalytic activity of Ln(OAr)3 changes in good concordanc...     

Kinetics and mechanism studies on scandium calix[6]arene complex initiating ring-opening polymerization of 2,2-dimethyltrimethylene carbonate

Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) using this complex can proceed under mild conditions. Poly (2,2-dimethyltrimethylene carbonate) (PolyDTC) with weight-average molecular weight of 33700 and molecular weight distribution of 1.21 can be prepared. Kinetics study indicates that the polymeri- zation rate is first order with respect to both monomer and initiator concentrations, and the apparent activation energy of the polymerization is 22.7 kJ/mol. 1H NMR spectrum of the polymer reveals that the monomer ring opens via acyl-oxygen bond cleavage leading to an active center of Sc-O.     

Enzymatic ring-opening polymerization of 2,2-dimethyltrimethylene carbonate catalyzed by PPL immobilized on silica nanoparticles

Silica nanoparticles were first used as the carrier for the porcine pancreas lipase (PPL) immobilization. The result of transmission electron microscopy (TEM) showed that the immobilized lipase was still in nanosize after enzyme immobilization. The ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) catalyzed by this immobilized PPL (IMPPL) was explored. ¹H NMR spectra suggested no evidence of decarboxylation during propagation. Influences of IMPPL concentration and reaction temperature on the molecular weight and yield of poly(DTC) were studied. The recovery and reuse of IMPPL for the ring-opening polymerization of DTC was also investigated. The recycling IMPPL showed even higher catalytic activity and a higher molecular weight of polycarbonate could be achieved.     

Rare earth complexes [Ln(EDBP)<Subscript>2</Subscript>(DME)Na(DME)<Subscript>3</Subscript>] as catalysts for the polymerization of 2,2-dimethyltrimethylene carbonate

The biphenol based discrete ion-pair rare earth complexes,[Ln（EDBP）₂（DME）Na（DME）₃][Ln=Er（1）,Yb（2）, Sm（3）],were prepared and used as catalysts for the ring-opening polymerization（ROP）of 2,2-dimethyltrimethylene carbonate（DTC）.Three complexes show moderate activities for the polymerization,and the catalytic activities increase in the following sequence:（Yb2 elimination was prepared.     

三(2,6-二叔丁基-4-甲基-苯氧基)镧催化ε-己内酯低温聚合特征及与环碳酸酯嵌段共聚

摘要用三(2,6-二叔丁基-4-甲基-苯氧基)镧[La(OAr)₃]在-15 ℃引发ε-己内酯(CL)的开环聚合, 发现聚合体系具有活性聚合特征. 在第二步聚合过程中继续补加第二种单体三亚甲基环碳酸酯(TMC)或二甲基三亚甲基环碳酸酯(DTC), 可得到CL与环碳酸酯的嵌段共聚物.     

Preparation and polymerization mechanism of dihydroxy-capped PCL,poly(CL-b-PEG-b-CL) and poly(DTC-b-CL-b-DTC)

PCL possesses a wide range of medical applications, such as tissue engineering and controlled drug release, because of its good biodegradability and miscibility. In order to extend the use of PCL, researchers have been exploring its structural and chemica…     

Homopolymerization of cyclic esters initiated by lanthanide isopropoxides supported by 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenolate) ligands

Lanthanide isopropoxides supported by carbon‐bridged bisphenolate ligands of 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenoxo) {[(EDBP)Ln(μ‐OPrⁱ)(THF)₂]₂, where Ln is Nd ( 1 ), Sm ( 2 ), or Yb ( 3 ) and THF is tetrahydrofuran} were synthesized by protic exchange reactions in high yields with Cp₃Ln compounds as raw materials, and complex 1 was structurally characterized. Complexes 1 – 3 were shown to be efficient initiators for the ring‐opening polymerization of ε‐caprolactone (ε‐CL) and 2,2‐dimethyltrimethylene carbonate (DTC). Complexes 1 – 3 could initiate the controlled polymerization of ε‐CL, and the polymerization rate was first‐order with respect to the monomer. The influence of the reaction conditions on the monomer conversion, molecular weight, and molecular weight distribution of the resultant polymers was investigated. End‐group analyses of the oligomers of ε‐CL and DTC showed that the polymerization underwent a coordination–insertion mechanism. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4409–4419, 2006     

The synthesis of polymer suspension with narrow particle size distribution for immunochemical investigations

 Heterophase polymerization of styrene in the presence of di-p-tolyl-o-carbalkoxyphenylcarbinol (DTC) soluble in monomer and insoluble in water, as stabilizer, was investigated. The factors affecting polymer particle diameter, their size distribution and stability were investigated. It was suggested that polymer particles are formed from monomer droplets. The polystyrene suspension with narrow particle size distribution synthesized in the presence of DTC, was used for immunochemical research. Received: 10 March 1998 Accepted: 8 June 1998     

聚2,2-二甲基三亚甲基碳酸酯与壳寡糖的接枝共聚反应研究

用新戊二醇和三光气为原料,反应生成2,2-二甲基三亚甲基碳酸酯.再以四氢呋喃为溶剂,酶为催化剂引发聚2,2-二甲基三亚甲基碳酸酯（PDTC）与壳寡糖接枝生成接枝共聚物.研究了温度、时间、配比对接枝共聚物的产率和分子量的影响.就产率而言,最佳反应条件是60℃、-NH2/DTC的摩尔比值为1∶10、36 h、DTC/酶的质量比值为200;就重均分子量而言,最佳反应条件是60℃、-NH2/DTC摩尔比为1∶10、36 h、DTC/酶质量比值为150.对产品进行红外光谱、凝胶色谱与溶解性能测试.     

Synthesis of reactive poly(norbornene): Ring‐opening metathesis polymerization of norbornene monomer bearing cyclic dithiocarbonate moiety

A norbornene monomer bearing cyclic dithiocarbonate moiety (NB‐DTC) was successfully synthesized from the corresponding precursor having epoxy moiety by its reaction with carbon disulfide. NB‐DTC underwent the ring‐opening metathesis polymerization (ROMP) catalyzed by a ruthenium carbene complex to give the corresponding poly(norbornene). The dithiocarbonate moiety incorporated into the side chain of the obtained poly(norbornene) reacted with amine to afford the corresponding thiourethane moiety with thiol group, which underwent oxidative S‐S coupling and/or addition reaction to the C‐C double bond in the main chain, leading to formation of a cross‐linked polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Comparative Kinetic Monte Carlo study of the Sulfinyl and Dithiocarbamate Precursor Route toward Highly Regioregular MDMO‐PPV

A comparative kinetic Monte Carlo (kMC) modeling study is presented for the synthesis of poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylenevinylene) (MDMO‐PPV) via the sulfinyl and dithiocarbamate (DTC) precursor route. The sulfinyl precursor route allows a much faster polymerization toward highly regioregular and high molar mass MDMO‐PPV starting from non‐equimolar amounts of the isomeric sulfinyl premonomers. In the DTC precursor route, the polymerization can be started from a single dithiocarbamate premonomer and a higher yield can be reached. In contrast, synthesis of highly regioregular MDMO‐PPV via the sulfinyl precursor route requires separation of the isomeric premonomers after their synthesis and before polymerization.

     

Isothiourea‐based lewis pairs for homopolymerization and copolymerization of 2,2‐dimethyltrimethylene carbonate with ε‐caprolactone and ω‐pentadecalactone

In this study, the homopolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and its copolymerizations with ε‐caprolactone (CL) were carried out in detail using the isothiourea‐based Lewis pairs comprised 2,3,6,7‐tetrahydro‐5H‐thiazolo(3,2‐a)pyrimidine and magnesium halides (MgX₂) with benzyl alcohol (BnOH) as the initiator. The copolymerization of DTC and CL via one‐pot addition produced randomly sequenced copolymers. On the other hand, a well‐defined linear poly(ε‐caprolactone)–block–poly(2,2‐dimethyltrimethylene carbonate) (PCL‐b‐PDTC) diblock copolymer was prepared by simple sequential ring‐opening polymerization of CL and DTC. In addition, poly(ω‐pentadecalactone)–block–PDTC diblock copolymer was successfully prepared by the same strategy. Moreover, PDTC–poly(ethylene glycol) (PEG)–PDTC triblock copolymer was synthesized in the presence of PEG 2000. The effects of different polymerization conditions on the polymerization reactions have been systematically discussed. The resulting polymers were characterized by the ¹H and ¹³C NMR spectra, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS). The block copolyester structures were confirmed by the ¹³C NMR spectroscopy and DSC characterizations. These results indicated that the supposed mechanism was a dual catalytic mechanism. The proposed mechanism involved activation of the monomer via coordination to the MgX₂, and the initiator alcohol was deprotonated by base. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2349–2355     

Preparation and polymerization mechanism of dihydroxy-capped PCL,poly(CL-<Emphasis Type="Italic">b</Emphasis>-PEG-<Emphasis Type="Italic">b</Emphasis>-CL) and poly(DTC-<Emphasis Type="Italic">b</Emphasis>-CL-<Emphasis Type="Italic">b</Emphasis>-DTC)

The ring opening polymerization of ε-caprolactone (CL) was initiated by glycol and yttrium tri(2,6-di-tert-butyl-4-methylphenolate)s (Y(OAr)₃), preparing dihydroxy-capped poly (ε-caprolactone) (PCL) with controllable molecular weight. ¹H NMR and SEC analyses indicate that two kinds of active species and corresponding PCL with different structures exist in the system. Increasing the ratio of glycol to Y(OAr)₃ benefits the formation of monofunctional active species. However, poly(ethylene glycol) (PEG)/Y(OAr)₃ system only contains sole bifunctional active species to synthesize copolymer of CL with PEG (poly(CL-b-PEG-b-CL)). Dihydroxycapped PCL as macroinitiator can further initiate the polymerization of 2,2-dimethyltrimethylene carbonate (DTC). Thus, triblock copolymer of CL with DTC (poly(DTC-b-CL-b-DTC)) has been prepared.     

Ring-opening polymerizaion of 2,2-dimethyltrimethylene carbonate initiated by <Emphasis Type="Italic">in situ</Emphasis> generated,tetrahydrosalen stablized yttrium borohydride complex and random copolymerization with <Emphasis Type="Italic">ɛ</Emphasis>-caprolactone

The poly（2,2-dimethyltrimethylene carbonate）（PDTC）with one hydroxyl and one formate terminal functions was synthesized by in situ generated,tetrahydrosalen stabilized yttrium borohydride complex.The influences of monomer/initiator molar ratio,temperature and reaction time on polymerization of DTC were investigated.Under the condition:[DTC]/[I]=500,55℃,toluene:0.5 mL,DTC:0.6 g,PDTC with M_n=15600 and PDI=2.15 was obtained. Through ¹H-NMR and ¹³C-NMR analyses,the structure of PDTC was characterized and a coordination-insertion mechanism was proposed.In addition,the random copolymerization of DTC and caprolactone（CL）initiated by rare-earth borohydride compound was studied.The microstructure of PDTC-co-PCL includes four diads:DTC-CL,CL-CL,DTC-DTC and CL-DTC, which were determined by the specific signals in ¹H-NMR spectra.Based on the typical signals of the formate（δ= 8.08）and hydroxyl（δ=3.34）end groups of PDTC-co-PCL,a mechanism involving DTC monomer inserts before CL during the initiation process was presumed.Furthermore,the thermal properties of amorphous copolymer were characterized by differential scanning calorimetry（DSC）.The results support the random structure of PDTC-co-PCL.     

Graft Copolymerization of Methyl Methacrylate onto Chitosan Initiated by Potassium Ditelluratocuprate(III)

A novel redox system, potassium ditelluratocuprate(III) (DTC)–chitosan, was employed to initiate the graft copolymerization of methyl methacrylate (MMA) onto chitosan in alkali medium. The effects of reaction variables, such as the initiator concentration, ratio of monomer to chitosan, the pH value, as well as reaction temperature and time were investigated, and the grafting conditions were optimized. Graft copolymers with both high grafting efficiency (>90%) and percentage of grafting were obtained, and the rate of polymerization is higher, which indicated that the DTC–chitosan redox system is an efficient initiator for this graft copolymerization. The structures and the thermal property of chitosan and chitosan–g–PMMA were characterized by infrared spectroscopy (IR), X‐ray diffraction and thermogravimetric analysis (TGA). A mechanism is proposed to explain the generation of radicals and the initiation. The graft copolymer was used as the compatibilizer in blends of terpolyamide and chitosan. The scanning electron microscope (SEM) photographs indicated that the graft copolymer improved the compatibility of the blend.     

Amphiphilic Block‐Graft Copolymers Poly(ethylene glycol)‐b‐(polycarbonates‐g‐palmitate) Prepared via the Combination of Ring‐Opening Polymerization and Click Chemistry

Amphiphilic block‐graft copolymers mPEG‐b‐P(DTC‐ADTC‐g‐Pal) were synthesized by ring‐opening polymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and 2,2‐bis(azidomethyl)trimethylene carbonate (ADTC) with poly(ethylene glycol) monomethyl ether (mPEG) as an initiator, followed by the click reaction of propargyl palmitate and the pendant azido groups on the polymer chains. Stable micelle solutions of the amphiphilic block‐graft copolymers could be prepared by adding water to a THF solution of the polymer followed by the removal of the organic solvent by dialysis. Dynamic light scattering measurements showed that the micelles had a narrow size distribution. Transmission electron microscopy images displayed that the micelles were in spherical shape. The grafted structure could enhance the interaction of polymer chains with drug molecules and improve the drug‐loading capacity and entrapment efficiency. Further, the amphiphilic block‐graft copolymers mPEG‐b‐P(DTC‐ADTC‐g‐Pal) were low cytotoxic and had more sustained drug release behavior. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

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.     

Determination of disulfiram and two of its metabolites in urine by reversed-phase liquid chromatography and spectrophotometric detection after post-column complexation

A selective method was developed for the determination of disulfiram and two of its metabolites, diethyldithiocarbamate (DTC) and copper (II) diethyldithiocarbamate [Cu(DTC)2], in complex (biological) samples by reversed-phase liquid chromatography (RP-LC) with post-column derivatization. In the first step, DTC is converted into lead (II) diethyldithiocarbamate [Pb (DTC)2] by adding lead (II) acetate. Disulfiram, Pb (DTC)2 and Cu (DTC)2 can be easily pre-concentrated on C18-bonded silica. After separation by isocratic RP-LC, derivation takes place in two solid state post-column reactors packed with metallic copper and copper (II) phosphate. Disulfiram reacts with metallic copper to form Cu (DTC)2. The same product is obtained by the ligand-exchange reaction between Pb (DTC)2 and copper (II) phosphate. Cu (DTC)2 can be detected selectively at 435 nm with good sensitivity (molar absorptivity, epsilon = 13,000). The derivatization reactions proceed rapidly and quantitatively, which was confirmed by comparison of absorption spectra. The applicability of this method is demonstrated for undiluted urine samples which, apart from the addition of lead (II) acetate and pre-concentration of C18-bonded silica, require no clean-up procedure.     

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

Aliphatic polycarbonates and their copolymers have been used in drug controlled release system and other biomedical applications due to their good biocompatibility, favorable mechanical properties and some elasticity1, such as poly(1, 3-dioxan-2-one)2 and…