Grafting acrylic polymers from flat nickel and copper surfaces by surface-initiated atom transfer radical polymerization

Acrylic polymers, including poly(methyl methacrylate), poly(2,2,2-trifluoroethyl methacrylate), poly( N,N'-dimethyaminoethyl methacrylate), and poly(2-hydroxyethyl methacrylate) were grafted from flat nickel and copper surfaces through surface-initiated atom transfer radical polymerization (ATRP). For the nickel system, there was a linear relationship between polymer layer thickness and monomer conversion or molecular weight of "free" polymers. The thickness of the polymer brush films was greater than 80 nm after 6 h of reaction time. The grafting density was estimated to be 0.40 chains/nm2. The "living" chain ends of grafted polymers were still active and initiated the growth of a second block of polymer. Block copolymer brushes with different block sequences were successfully prepared. The experimental surface chemical compositions as measured by X-ray photoelectron spectroscopy agreed very well with their theoretical values. Water contact angle measurements further confirmed the successful grafting of polymers from nickel and copper surfaces. The surface morphologies of all samples were studied by atomic force microscopy. This study provided a novel approach to prepare stable functional polymer coatings on reactive metal surfaces.     

Use of a trichloromethyl-terminated azo initiator to synthesize block copolymers by consecutive conventional radical polymerization and ATRP

A new two-step procedure for the preparation of block copolymers by a free radical process is proposed. A trichloromethyl-terminated azo initiator is synthesized and subsequently used to polymerize a first monomer, leading to a trichloromethyl-functionalized polymer. Secondly, the preformed polymer is used as a macroinitiator to initiate the atom transfer radical polymerization (ATRP) of a second monomer, to generate a block copolymer. The principle of this method is illustrated with butyl acrylate as the first monomer, and styrene for the ATRP step.     

Novel Reactive Polymers Containing Hemiacetal Ester and Vinyl Moieties: Synthesis and Selective Polymerization of 1‐Methoxyallyl Methacrylate Derived from Methacrylic Acid and Methoxyallene

A novel functional monomer, 1‐methoxyallyl methacrylate (MOAMA), was prepared and its polymerization behavior was investigated. The radical polymerization of MOAMA led to a polymeric network due to the participation of the allyl group in the reaction. Contrarily, anionic polymerization proceeded in a living fashion to yield linear poly(MOAMA) without gelation. Since both the network‐type and linear polymers possess hemiacetal ester and vinyl moieties, the two‐fold polymerization behavior of MOAMA represents a new pathway towards reactive polymers.     

Complexation du chlorure de vinyle par le tetrahydrofuranne et le n-butyraldéhyde: Étude par résonance magnétique nucléaire haute résolution

Examination of the HR-NMR spectra of vinyl chloride in the presence of tetrahydrofuran and n-butyraldehyde suggests the formation of donor-acceptor type complexes. The equilibrium quotients and NMR constants were estimated by using the Benesi-Hildebrand method. The existence of these complexes would explain the anomalies observed: first, in the anionic polymerization of vinyl chloride initiated by tert-butylmagnesium chloride is tetrahydrofuran. The initiation step seems to be governed by this complexation phenomenon; second, in the radical polymerization of the same monomer in n-butylaldehyde the obtained poly(vinyl chloride) is more syndiotactic than the radical polymer prepared in bulk by the usual methods.     

手性化合物环境下制备甲壳型液晶高分子

甲壳型液晶高分子的研究是我国独创[1 ,2 ] ,已产生了积极的科学影响 .虽然它们在化学结构上属于侧链型 ,但在分子形态上更接近于主链型液晶高分子[3] .由于庞大的液晶基元对空间的要求 ,液晶高分子主链被迫采取尽可能伸展的构象[4,5] .然而 ,至今尚不清楚主链与液晶基元之间是怎样协同作用以形成有序结构 .本文探索了在不同手性化合物环境下制备单手螺旋链甲壳型液晶高分子的可能性 .尽管最后并未获得螺旋链高分子 ,但仍取得了一些有价值的结果 .手性化合物环境分别是 ( )薄荷醇 ( 1 )作为反应溶剂、( )过氧化 二 (碳酸薄荷醇酯 ( 2 )作…     

含糖聚合物的合成

综述了含糖聚合物合成的研究发展，介绍了化学和酶催化合成不饱合含糖单体的方法，以及含糖聚合物通过自由基、阳离子、阴离子聚合和高分子改性等四种方法制备途径，同时也探讨了这些含糖聚合物在医药、生物材料、水凝胶等领域中的应用。     

Synthesis of PMMA‐b‐PBA block copolymer in homogeneous and miniemulsion systems by DPE controlled radical polymerization

In this research, poly(methyl methacrylate)‐b‐poly(butyl acrylate) (PMMA‐b‐PBA) block copolymers were prepared by 1,1‐diphenylethene (DPE) controlled radical polymerization in homogeneous and miniemulsion systems. First, monomer methyl methacrylate (MMA), initiator 2,2′‐azobisisobutyronitrile (AIBN) and a control agent DPE were bulk polymerized to form the DPE‐containing PMMA macroinitiator. Then the DPE‐containing PMMA was heated in the presence of a second monomer BA, the block copolymer was synthesized successfully. The effects of solvent and polymerization methods (homogeneous polymerization or miniemulsion polymerization) on the reaction rate, controlled living character, molecular weight (M_n) and molecular weight distribution (PDI) of polymers throughout the polymerization were studied and discussed. The results showed that, increasing the amounts of solvent reduced the reaction rate and viscosity of the polymerization system. It allowed more activation–deactivation cycles to occur at a given conversion thus better controlled living character and narrower molecular weight distribution of polymers were demonstrated throughout the polymerization. Furthermore, the polymerization carried out in miniemulsion system exhibited higher reaction rate and better controlled living character than those in homogeneous system. It was attributed to the compartmentalization of growing radicals and the enhanced deactivation reaction of DPE controlled radical polymerization in miniemulsified droplets. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4435–4445, 2009     

Synthesis of heteroarm star polymers comprising poly(4-methylphenyl vinyl sulfoxide) segment by living anionic polymerization

<正>A series of 3-arm ABC and AA'B and 4-arm ABCD,AA'BC and AA′A″B heteroarm star polymers comprising one poly(4-methylphenyl vinyl sulfoxide) segment and other segments such as polystyrene,poly(α-methylstyrene), poly(4-methoxystyrene) and poly(4-trimethylsilylstyrene) were synthesized by living anionic polymerization based on diphenylethylene(DPE) chemistry.The DPE-functionalized polymers were synthesized by iterative methodology,and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers.The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide(MePVSO) initiated from the in situ formed polymer anion with two or three polymer segments.The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well.Both approaches could afford the target heteroarm star polymers with predetermined molecular weight,narrow molecular weight distribution (M_w/M_n1.03) and desired composition,evidenced by SEC,~1H-NMR and SLS analyses.These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.     

Two-Dimensional Chromatographic Analysis of Polystyrene-block-poly(methyl methacrylate) Copolymers Synthesized by Selective Oxidation of Polystrene-9-borabicyclo[3.3.1]nonane

Summary: The preparation of polystyrene block methyl methacrylate copolymers (PS-b-PMMA) is described. The polystyrene segment was prepared by anionic polymerization and the methylmethacrylate segment was prepared via free radical autoxidation of a borane agent attached to the styrene chain. 1 The chemistry involves a transformation of the anionic polymerization process to borane chemistry by firstly producing polystyrene with chain end unsaturated alkyl functional groups prepared using a n-butyllithium initiator and termination with allylchlorodimethylsilane. Secondly, the unsaturated macroinitiator end was hydroborated by 9-borabicyclo[3.3.1]nonane (9-BBN) to produce a borane terminated PS. Thirdly, the borane group at the chain end was selectively oxidized and converted to polymeric radicals in the presence of methyl methacrylate which then initiated radical polymerization to produce block copolymers. The polymer obtained was characterized using several chromatographic techniques including LC-CC (liquid chromatography under critical conditions) for the polystyrene segments and two-dimensional chromatography with LC-CC in the first dimension and SEC in the second. The results show that block formation was successful although significant homopolymerization of methyl methacrylate is also obtained.     

Copolymerization in N-vinylcaprolactam-N-vinylpyrrolidone and N,N-diethylacrylamide-N,N-dimethylacrylamide systems: The effect of composition and spatial structure of copolymers on their thermal sensitivity

Factors that affect the temperature-responsive properties of water-soluble polymers were revealed by studying the copolymerization of two pairs of monomers: N-vinylcaprolactam-N-vinylpyrrolidone and N,N-diethylacrylamide-N,N-dimethylacrylamide. In each pair, the first monomer forms a temperature-responsive polymer and the second gives a polymer soluble in water up to the boiling point. It was found that in all cases, the addition of the second (more hydrophilic) monomer resulted in a monotonous increase in the phase separation temperature in an aqueous copolymer solution, with the temperature rise being comparatively slow in the initial stage and sharply accelerating after the addition of more than 40–50 mol % second monomer. The phase-separation temperature versus copolymer composition curves for N,N-diethylacrylamide-N,N-dimethylacrylamide copolymers of iso-and heterotactic structure synthesized via anionic polymerization are rather similar. At the same time, the copolymers of both types prepared via radical polymerization are characterized by steeper curves, a pattern that may be due to a high content of the syndiotactic structure, however, changes in the copolymer spatial structure have a lesser effect on the phase separation temperature than the presence of units of a more hydrophilic monomer. The addition of a relatively low amount (20–25 mol %) of a less hydrophilic monomer imparts temperature sensitivity to polymers, such as polyvinylpyrrolidone or polydimethylacrylamide, which do not possess this property in the pure form.     

RAFT聚合合成一种即含甲酰基又含手性β-蒎烯单元聚合物

设计并合成了一种新型含甲酰基同时又含β-蒎烯单元的新单体2-β-蒎氧基-5-乙烯基苯甲醛(POVB),选择苯基双硫代乙酸1-苯基乙酯(PEPDA)为RAFT试剂、以AIBN为引发剂、在60℃下THF中实现了POVB的"活性"/可控RAFT自由基聚合.单体浓度半对数ln([M]0/[M])与聚合时间符合线性关系,聚合过程呈现一级动力学特征;聚合物分子量(Mn)随单体转化率几乎线性增加,而且整个反应过程中分子量分布(Mw/Mn1.2)保持在较窄的范围.1H-NMR的分析进一步证实了聚合物链的末端精细结构.此外,CD谱结果表明手性单元β-蒎烯基能赋予聚合物以光学活性.     

The preparation of poly(N-acetyl-α-amino acrylic acid) [poly(N-acetyl dehydroalanine)] and poly(α-amino acrylic acid) (polydehydroalanine)

Poly(N-acetyl-α-amino acrylic acid) was prepared by a free radical polymerization reaction. Mild alkaline hydrolysis of the polymer product yielded a second polymer poly(α-amino acrylic acid) (polydehydroalanine). Both polymers exhibited certain polyelectrolyte behavior, although the latter did not behave as expected for an amphoteric polyelectrolyte.     

Synthesis of block‐graft polymers by anionic polymerizations

Two poly(4‐methylstyrene) (P4MS)‐block‐polystyrene (PS)‐block‐P4MS triblock copolymers were prepared by successive anionic addition of styrene and 4‐methylstyrene monomers as the core backbone ( CB ) for the architecture of block‐graft polymers. Both terminal 4‐methylstyrene blocks of CB were metalated with a sec‐butyllithium (sec‐BuLi)/tetramethylethylenediamine (TMEDA) complex in cyclohexane. The first‐generation block‐graft polymer ( 1BG ) was prepared by anionic polymerization of α‐methylstyrene by the lithiated CB in tetrahydrofuran (THF) at –78°C and subsequently the terminal graft ends were capped with a small amount of 4‐methylstyrene. The characterization of those block‐graft polymers was carried out in detail.     

Anionic synthesis of well-defined polymer blends by controlled chain-transfer reactions

The scope and limitations of controlled chain transfer reactions in living anionic polymerization have been investigated. In contrast to the random nature of normal chain transfer reactions, this procedure first effects controlled living anionic polymerization followed by addition of a stoichiometric amount of suitable chain transfer agent when the monomer has been completely consumed. The resulting anionic species is then used to initiated polymerization of a second monomer charge with the same monomer or with a different monomer. A variety of hydrocarbon acids and amine compounds with pKa values in the range of 30–40 have been evaluated as chain transfer agents in the presence and absence of coordinating ligands. Efficient chain transfer to poly(styryl)lithium has been observed using 1,1-diphenylpropane. Reinitiation efficiency to both styrene and butadiene monomer was quantitative and controlled blends of different molecular weight polystyrenes or blends of polystyrene with polybutadiene have been prepared. The use of these chain transfer reactions to prepare functionalized polymers has also been investigated.     

Polymerization of oligo(ethylene glycol) (meth)acrylates: Toward new generations of smart biocompatible materials

Monomers composed of a (meth)acrylate moiety connected to a short poly(ethylene)glycol (PEG) chain are versatile building‐blocks for the preparation of “smart” biorelevant materials. Many of these monomers are commercial and can be easily polymerized by either anionic, free‐radical, or controlled radical polymerization. The latter approach allows synthesis of well‐defined PEG‐based macromolecular architectures such as amphiphilic block copolymers, dense polymer brushes, or biohybrids. Furthermore, the resulting polymers exhibit fascinating solution properties in aqueous medium. Depending on the molecular structure of their monomer units, non linear PEG analogues can be either insoluble in water, readily soluble up to 100 °C, or thermoresponsive. Thus, these polymers can be used for building a wide variety of modern materials such as biosensors, artificial tissues, smart gels for chromatography, and drug carriers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3459–3470, 2008     

A versatile approach for the preparation of end‐functional polymers and block copolymers by stable radical exchange reactions

A versatile strategy for the preparation of end‐functional polymers and block copolymers by radical exchange reactions is described. For this purpose, first polystyrene with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl end group (PS‐TEMPO) is prepared by nitroxide‐mediated radical polymerization (NMRP). In the subsequent step, these polymers are heated to 130 °C in the presence of independently prepared TEMPO derivatives bearing hydroxyl, azide and carboxylic acid functionalities, and polymers such as poly(ethylene glycol) (TEMPO‐PEG) and poly(ε‐caprolactone) (TEMPO‐PCL). Due to the simultaneous radical generation and reversible termination of the polymer radical, TEMPO moiety on polystyrene is replaced to form the corresponding end‐functional polymers and block copolymers. The intermediates and final polymers are characterized by ¹H NMR, UV, IR, and GPC measurements. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2387–2395     

SYNTHESIS AND CHARACTERIZATION OF WELL-DEFINED BLOCK COPOLYMERS CONTAINING PENDANT, SELF-COMPLEMENTARY QUADRUPLE HYDROGEN BONDING SITES

The title block copolymer (defined as PSUEA) containing pendant,self-complementary quadruple hydrogen bonding sites has been prepared successfully by three steps.First,poly(styrene-b-2-hydroxyethyl acrylate) (defined as PSHEA) was prepared by living radical polymerizing 2-hydroxyethyl acrylate (HEA) initiated by polystyrene (PSt) macro- initiator,which was prepared via nitroxide-mediated polymerization (NMP) technique.After treated by excessive 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPD...     

Encapsulation and dispersion of carbon black by an in situ controlling radical polymerization of AA/BA/St with DPE as a control agent

In this paper, a new strategy to encapsulate and disperse carbon black by an in situ controlling free radical polymerization of 1,1-Diphenylenthyene (DPE) method was developed. Firstly, a living amphipathic precursor polymer of P (AA-BA) containing DPE unit was synthesized. This precursor could be grafted or absorbed on the surface of small carbon black particles to prevent further aggregation of carbon black. And the DPE unit in the living amphipathic precursor could initiate following monomer to form polymer shell via in situ polymerization. Carbon black/polymer core-shell composite particles with 69.6 wt.% polymer shell were prepared. The encapsulated carbon black had a small particle size and high performance on dispersibility and stability. Encapsulation mechanism of this method was confirmed by analyses of TEM, UV–vis, ¹H NMR, ¹³C NMR, TGA, and other instruments.     

Chain-growth polycondensation for well-defined condensation polymers and polymer architecture

The historical development of our research on polycondensation that proceeds in a chain-growth polymerization manner ("chain-growth polycondensation") for well-defined condensation polymers is described. We first studied polycondensation in which change of the substituent effect induced by bond formation drove the reactivity of the polymer end group higher than that of the monomer. In this approach, well-defined aromatic polyamides, polyesters, polyethers, and poly(ether sulfone)s were obtained. The second approach was the study of the phase-transfer polymerization of a solid monomer dispersed in an organic solvent. In this type of polymerization, the solid monomer was physically unable to react with another monomer and was carried with the phase transfer catalyst into the solution phase where it reacted with an initiator and the polymer end group in the solvent in a chain polymerization manner. We also found catalyst-transfer polycondensation as a third approach to chain-growth polycondensation. In the Ni-catalyzed polycondensation of 2-bromo-5-chloromagnesiothiophenes, the Ni catalyst transferred to the polymer end group, and a coupling reaction occurred there to yield a well-defined polythiophene. This chain-growth polycondensation was applied to the synthesis of condensation polymer architectures such as block copolymers, star polymers, graft copolymers, and so on.     

Synthesis of Vinyl Polymer—Poly (α-Amino Acid) Block Copolymers by End-Reactive Oligomers

In order to synthesize block copolymers consisting of segments having dissimilar properties, vinyl polymer - poly (α-amino acid) block copolymers were synthesized by two different methods. In the first method, the terminal amino groups of polysarcosine, poly(γ-benzyl L-glutamate), and poly(γ-benzyloxycarbonyl-L-lysine) were haloacetylated. The mixture of the terminally haloacetylated poly (α-amino acid) and styrene or methyl methacrylate was photoirradiated in the presence of Mo (CO)₆ or heated with Mo(CO)₆, yielding A-B-A-type block copolymers consisting of poly(α-amino cid) (the A component) and vinyl polymer(the B component). The characterization of block copolymers revealed that the thermally initiated polymerization of vinyl compounds by the trichloroacetyl poly(α-amino acid)/Mo(CO)₆ system was most suitable for the synthesis of vinyl polymer - poly-(α-amino acid) block copolymers. In the second method, poly (methyl methacrylate) and polystyrene having a terminal amino group were synthesized by the radical polymerization in the presence of 2-mercaptoethylammonium chloride. Using these polymers having a terminal amino group as an initiator, the block polymerizations of γ-benzyl L-glutamate NCA and e-benzyloxycarbonyl-L-lysine NCA were carried out, yielding A-B-type block copolymer. By eliminating the protecting groups of the side chains of poly(α-amino acid) segment, block copolymers such as poly(methyl methacrylate) with poly(L-glutamic acid) or poly(L-lysine) and polystyrene with poly(L-glutamic acid) and poly(L-lysine) were successfully synthesized.