Asymmetric Polymerization of Menthyl Methacrylate by Anionic Catalysts

In this paper,(-) menthyl methacrylate(-) MnMA) was polymerized at -78℃ in toluene with three types of anionic catalysts, which were complexes of fluorenyllithium with (-) sparteine-((-)-Sp),(S,S)-( )-2,3-dimethoxy-1,4-bis(dimethylamino) butane( )DDB) and N,N,N,N′-tetra-methylethylenediamine(TMEDA), and the chiral optical property of the obtained polymer was studied. The circular dichroism (CD) spectrum of the polymer showed negative Cotton effect.     

Polymerization of 4—Vinylpyridine by Lanthanide Coordination Catalyst

Polyvinylpyridines are an important class of polymers that exhibit interesting properties due to the presence of the nitrogen atom in the pyridine ring. The weakly basic nitrogen atom makes possible a variety of reactions on vinylpyridine polymers, e.g. reaction with acids, quaternization and complexation of metals. In addition, these polymers are mainly attractive in applications as polyelectrolytes, polymeric reagents etc. Few papers about polymerization of 4-vinylpyridine (4-Vpy) with co…     

Evaluation of Transient Absorption Spectra of N,N,N’,N’—Tetra—（p—methylphenyl）

Photoinduced electron transfer processes between fullerenes(C60/C70)and N,N,N’,N’-tetra-(p-methylphenyl-4,4’-diamino-1,1’-diphenyl ether(TPDAE)have been studied by nanosecond laser flash photolysis.Quantum yields and rate constants of electron trasfer from TPDAE to excited triplet state of fullerenes(C60/C70)in benzonitrile have been evaluated by observing the trasient absorption bands in the near-IR region where the excited triplet state.radical anion of fullerenes(C60/C70)and radical cations of TPDAE appear.     

Dendritic Macroinitiator for the Ring—Opening Polymerization of γ—Benzyl L—Glutamate N—Carboxyanhydride

Much effort has been dedicated to the molecular design and synthesis of model proteins to define protein folding interactions and to develop protein-based materials. Among them, the ring-opening polymerization of -amino acid-N-carboxyanhy- drides (NCAs) has drawn much attention because the resulting artificial polypeptides have wide applications in biotechnology, biomineralization and diagnostics1, 2. It is well known that dendrimers are hyperbranched macromolecules possessing a very high co…     

Copolymerization of Styrene with N—phenylmaleimide by Rare Earth Coordination Catalysts

Copolymerization of styrene (St) with N-phenylmaleimide(NPMI) was studied with rare earth coordination catalyst Nd(naph)3-AlEts in toluene. Characterization of the copolymers showed that the copolymers possess an alternating structure.     

分子筛选择催化合成N，N—二甲基苯胺（DMA）

本文报道在改性的ZSM－5分子筛催化剂上，苯胺和甲醇的气相甲基化反主尖，研究发现，在300℃和常压下，液时空速为1.0h^-1和苯胺／甲醇摩尔比为1／3的条件下，改性的ZSM－5催化剂对DMA贩选择率为88.5％，苯胺转化率为97.8％，此结果有明显的应用前景。     

(甲基)丙烯酸氟烷基酯的“活性”/可控聚合

带氟烷基侧链的(甲基)丙烯酸氟烷基酯聚合物是一类具有独特表面性能和光学特性的氟聚合物,传统的自由基共聚合由于无法调节聚合物的微细结构和氟原子的分布,限制了该类聚合物在更广领域的应用.活性聚合为聚合物分子设计和合成提供了一个有效方法,利用活性聚合方法可以获得预期结构和性能的含氟嵌段聚合物材料.由于引入了氟烷基侧链,(甲基)丙烯酸氟烷基酯的活性聚合又有其特殊性,本文针对它的活性阴离子聚合、基因转移聚合、活性自由基聚合等方面作一综述.     

Synthesis of (meth)acrylate Block Copolymers by Ligated Anionic Polymerization

Synthetic potential of the ligated anionic polymerization (LAP) of acrylic and metacrylic esters initiated with methyl 2-lithioisobutyrate (MIB-Li) in the presence of an excess of alkali metal tert-alkoxides (prevailingly Li tert-butoxide) is presented. tert-Alkoxides form with ester-enolates, like MIB-Li, cross-aggregates of various composition, which tailor the environment of growing chain-ends, lower their nucleophilicity and restrict in this way the extent of side reactions, in particular self-termination of growing macroanions by back-biting reaction. Thus, stability of polymethacrylate living chains is sufficiently high for methacrylate and acrylate block copolymers to be synthesized. In the case of acrylate polymerization, reaction conditions must be optimized due to their high tendency to self-termination.     

采用阴离子、基团转移及自由基聚合方法合成旋光性聚甲基丙烯酸薄荷酯

近年来, 旋光性高分子的广泛应用及其特有的功能已引起了广泛关注, 尤其在手性记忆功能材料[1～3]、液晶及手性催化等方面[4～6]皆表现出良好的应用前景. 用旋光性单体合成旋光性聚合物是最常用的方法之一. 早在20世纪70年代, 就有关于聚甲基丙烯酸薄荷酯(PMnMA)的研究[7], 但有关配体参与的阴离子聚合, 基团转移聚合(GTP)及其立构规整性的研究还未见报道.     

Controlled Synthesis and Degradation of Poly(N‐(isobutoxymethyl) acrylamide) Homopolymers and Block Copolymers

The homopolymerization of the water‐insoluble N‐(isobutoxymethyl)acrylamide (IBMA) is investigated for the first time by nitroxide‐mediated polymerization. The homopolymerization is characterized by a linear increase in number average molecular weight (M_n) versus conversion (X) to X > 0.80 while maintaining dispersities of M_w/M_n < 1.30. A strong Arrhenius relationship correlates the apparent rate constants and the homopolymerization temperatures between 105 and 120 °C. All poly(IBMA) homopolymers are then successfully chain‐extended with styrene (S) to form well‐defined block copolymers of poly(IBMA)‐b‐poly(S) suggesting a high degree of livingness of the poly(IBMA) macroinitiators. Thermogravimetric analysis and differential scanning calorimetry are both used to characterize the thermal properties of the homopolymers and block copolymers and identify possible unique degradation of the poly(IBMA) block through imide formation at elevated temperatures.

     

Effect of acrylamide concentration on the kinetics of oxidation of tartaric acid by cerium(IV) in sulfuric-perchloric acid media

The kinetics of oxidation of tartaric acid by Ce(IV) in the absence and presence of acrylamide has been investigated spectrophotometrically in aqueous H₂SO₄–HClO₄ media at a constant ionic strength 2.0M and 25°C. Oxidation of tartaric acid in both cases was first order with respect to Ce(IV). Kinetic data showed that the reaction involves the formation of an unstable complex and an intermediate free radical. The activation parameters were calculated to be E _a =91.3±0.4 kJ-mol^–1, S=20.2±1.0 J-mol^–1-K^–1, H=88.8±0.4 kJ-mol^–1. A polymerization mechanism is discussed.     

Chirality Transfer in the Formation of Poly(oxymethylene) Helices by Anionic Polymerization

In this article, we present the synthesis of a series of oligo(oxymethylenes) capped with 1‐phenylethanol and MeOH. The anionic condition affords enantiomerically pure oligo(oxymethylene) oligomers, while the cationic oligomerization leads to a racemic mixture of the oligo(oxymethylene) chain.     

Synthesis of poly(N‐[tris(hydroxymethyl)methyl]acrylamide) functionalized porous silica for application in hydrophilic interaction chromatography

Porous silica coated by a highly hydrophilic and nonionic tentacle‐type polymeric layer was synthesized by free radical “grafting from” polymerization of N‐[2‐hydroxy‐1,1‐bis(hydroxymethyl)ethyl]‐2‐propenamide (TRIS‐acrylamide) in partly aqueous solutions. The radical initiator sites were incorporated on the silica surfaces via a two‐step reaction comprising thionyl chloride activation and subsequent reaction with tert‐butyl hydroperoxide. The surface‐bound tert‐butylperoxy groups were then used as thermally triggered initiators for graft polymerization of TRIS‐acrylamide. The synthesized materials were characterized by diffusive reflectance Fourier transform infrared specotroscopy, X‐ray photoelectron spectroscopy, and CHN elemental analysis. Photon correlation spectroscopy was used to determine changes in ζ‐potentials resulting from grafting, ²⁹Si magic angle spinning nuclear magnetic resonance spectroscopy (MAS‐NMR) spectroscopy was used to assess the ratio of silanol to siloxane groups in the substrate and the grafted material, and the changes in surface area and mesopore distribution were determined by nitrogen cryosorption. Chromatographic evaluation in hydrophilic interaction chromatography (HILIC) mode showed that the materials were suitable for use as stationary phases, featuring good separation efficiency, a comparatively high retention, and a selectivity that differed from most commercially available HILIC phases. A comparison of this neutral phase with a previously reported N‐(2‐hydroxypropyl)‐linked TRIS‐type hydrophilic tentacle phase with weak anion exchange functionality revealed substantial differences in retention patterns.     

Green Polymer Chemistry: Microwave‐Assisted Single‐Step Synthesis of Various (Meth)acrylamides and Poly(meth)acrylamides Directly from (Meth)acrylic Acid and Amines

Summary: Various (meth)acrylamides were synthesized in good yields directly from (meth)acrylic acid and an amine using microwave irradiation in a solvent‐free environment. Under the applied conditions the (meth)acrylic function is preserved. Furthermore, the addition of an initiator like 2,2′‐azoisobutyronitrile (AIBN) to the starting mixture leads directly to poly(meth)acrylamides in a single step.

General reaction scheme for the formation of poly(meth)acrylamides from the microwave‐assisted reaction of (meth)acrylic acid and various amines.     

氧阴离子引发甲基丙烯酸-2-(N,N-二甲氨基)乙酯聚合制备Y型大分子单体

氧阴离子聚合(Oxyanion－initiated Polymerization)是一类新型的聚合方法[‘,’‘．利用个乙烯基苦醇钾作为功能性引发剂,引发甲基丙烯酸－2－(NJ－二乙氨基)乙酯聚合,形成末端带可聚合官能团的大分子单体‘”“．氧阴离子引发剂通常难以引发甲基丙烯酸烷基酯单体聚合,但却能引发甲基丙烯酸氨基酯类单体发生聚合．由于氨基乙酯基7位上氮原子的供电子性,它能与钾离子形成螫合物,使氧阴离子的亲核性增加,从而更具有活性,引发单体聚合．氧阴离子聚合具有速度快、活性高、反应温度接近室温和产物的单分散性好等特点．尽管目前还不清楚这种反…