Studies on the Self-condensing Vinyl Polymerization of a Novel Maleimide Inimer

The self-condensing vinyl polymerization(SCVP) of a novel maleimide inimer(initiator-monomer) 1, N-(4-α-bromobutyryloxy phenyl) maleimide with the complex of CuBr/Bipy(2, 2′-bipyridine) as the catalyst was studied. GPC was used to determine the molecular weight and the results show that the molecular weight increases exponentially with polymerization time during the first hour, and then the rate of increase molecular weight slows down. The molecular weight also increases with increasing dosage of the catalyst. The coincidence of the molecular weights determined by 1H NMR and GPC proves that the polymer obtained from the SCVP of inimer 1 has a linear structure, which is further verified by 13C NMR spectrum. A hyperbranched polymer was obtained by the copolymerization of inimer 1 and styrene.

Statistical and thermodynamic properties of binary self-condensing vinyl polymerization

The thermodynamic properties of a binary self-condensing vinyl polymerization system consisting of monomers and inimers are investigated by the principle of statistical mechanics.In detail,in terms of two types of canonical partition functions constructed from different viewpoints,the equilibrium free energy,the law of mass action and the size distribution of hyperbranched polymers are obtained.As an application,the specific heat,equation of state and isothermal compressibility concerning the polymerization are given as well.To study the dimension of hyperbranched polymers in the system,a recursion formula satisfied by the(k+1)-th and k-th mean square radius of gyration is derived,and then the first,second and third radius of gyration under different solvent conditions are presented.The influences of the fraction of inimers,the conversion of vinyl groups and the solvent effect on the average dimension of hyperbranched polymers are discussed.

A SYNTHETIC APPROACH FOR WATER SOLUBLE HYPERBRANCHED POLY(N,N-ETHYLIDENEBIS(N-2-CHLOROACETYL ACRYLAMIDE)) WITH HIGH DEGREE OF BRANCHING VIA ATOM TRANSFER RADICAL POLYMERIZATION/SELF-CONDENSING VINYL POLYMERIZATION

A novel acrylamide A2B2＊ （A = alkene, B＊ = alkyl chlorine） type inimer was obtained from commercially available 1,2-ethylenediamine, chloroacetyl chloride and acryloyl chloride. The as-prepared monomer can form water-soluble hyperbranched poly（N,N-ethylidene bis（N-2-chloroacetyl acrylamide））s （HPECA） through atom transfer radical polymerization/self-condensing vinyl polymerization method in the presence alkyl chlorine/CuCl/2,2-bipyridine activation system which can effectively suppress the gelation formation.1H-NMR spectra and dual detector size exclusion chromatography proved the hyperbranched structure indisputably, and the degree of branching was determined by the detailed analyses of 1H-NMR spectra. The trend of the degree of branching was in consistent with the result of Mark- Houwink exponent a. The experiment results suggested that the conversion was 67%, Mw = 13.2 x 104, Mark-Houwink a = 0.282 and the degree of branching = 64% when the reaction temperature was 120 ℃, reaction time = 168 h and N,N- ethylidene bis（N-2-chloroacetyl acrylamide）：Cu（I） = 50：0.62.

Studies on the Self-condensing Vinyl Living Radical Polymerization of a Novel Acrylate Inimer

A novel acrylate inimer, 2-（2-chloroacetyloxy） ethyl acrylate, was prepared by the reaction of 2-hydroxyethyl acrylate with chloroacetyl chloride in the presence of triethylamine. The self-condensing vinyl living radical polymerization of the inimer was studied and the hyperbranched macromolecules containing ester linkages on their backbone were prepared. All the polymerization products were characterized by 1H NMR. The polymerization degree and the branching parameter were calculated based on the 1H NMR spectra. It has been shown that this inimer exhibits a very distinctive polymerization behavior. Similar to step-growth polymerization, the polymerization degree of the products formed increased exponentially during the early stage of the polymerization, and then the increasing rate slowed down. However, the inimer remained present throughout the polymerization consistent with conventional free radical polymerization. Also, if much longer polymerization time was used, the polymerization system would become gel due to the crosslinking reaction derived from radical-radical recombination. As a result of the unequal reactivity of -CH2Cl and >CHCl, an almost linear product was obtained at a molar ratio of bipy to inimer=0.05, while a relatively high ratio of bipy to inimer 1 favored the formation of the branched structure. The macromolecules formed at a high ratio of bipy to inimer 1 exhibited an excellent solubility in organic solvents such as acetone.

A Unified Theoretical Treatment on Statistical Properties of the Semi-batch Self-condensing Vinyl Polymerization System

We present a novel generating function(GF)method for the self-condensing vinyl polymerization(SCVP)system with any initial distribution of preexisted polymers.Such a method was proven to be especially useful to investigate the semi-batch SCVP system allowing a sequence of feeding operations during the polymerization.Consequently,the number-,weight-,and z-average molecular weights as well as dispersity index of hyperbranched polymers can be explicitly given,which are determined by predetermined feeding details and conversions in each polymerization step.These analytical results are further confirmed by the corresponding Monte Carlo simulations.Therefore,the present GF method has provided a unified treatment to the semi-batch SCVP system.Accordingly,hyperbranched polymers with desired properties can be prepared by designing feeding details and presetting conversions at each step based on the present GF method.

Kinetic theory of self-condensing vinyl polymerization

This review introduces the kinetic theory of self-condensing vinyl polymerization (SCVP),including the SCVP of AB inimers,the SCVP with non-equal reactivity between A and B groups,the SCVP in the presence of a small amount of multifunctional initiators,also the SCVP of both inimers and comonomers.The analytical expressions of various molecular parameters for the resulting hyperbranched polymers,such as the molecular size distribution function,the average molecular weight,the polydispersity index and the degree of branching,are reviewed systematically.

Synthesis of Highly Branched Poly(ε-caprolactone) by Self-condensing Atom Transfer Radical Polymerization of Macroinimers

Branched poly（ε-capmlactone） was synthesized by self-condensing atom transfer radical polymerization of macroinimer, α-acryloyoxy-ω-2-bromopropionyloxy poly（ε-caprolactone）, which was prepared by enzyme-catalyzed ring-opening polymerization of ε-caprolactone with 2-hydroxylethyl acrylate as initiator and esterification of the ω-hydroxyl group of the obtained poly（ε-caprolactone） by 2-bromopropionyl bromide.

PARTICLE MORPHOLOGY OF POLY(VINYL CHLORIDE)RESIN PREPARED BY SUSPENDED EMULSION POLYMERIZATION

Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases anddisappears at conversions greater than 30%. Scanning electron micrographs show that PVC grains are composed of looselycoalesced primary particles, especially for PVC resins prepared in the presence of poly(vinyl alcohol) dispersant. The size ofprimary particles increases and porosity decreases with the increase of conversion. In view of the particle features of PVCresin, a particle formation mechanism including the formation of primary particles and grains is proposed. The formationprocess of primary particles includes the formation of particle nuclei, coalescence of particle nuclei to form primary particles,and growth of primary particles. PVC grains are formed by the coagulation of primary particles. The loose coalescence ofprimary particles is caused by the colloidal stability of primary particles and the low swelling degree of vinyl chloride in the primary particles.

Influence of Suspended Emulsion Polymerization Conditions on Particle Characteristics of Polyvinyl Chloride Resin

Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.

Enzymatic Regioselective Synthesis of Vinyl Lactose Ester and Its Chemical Polymerization

Transesterification reaction of lactose with divinyladipate in pyridine catalyzed by an alkaline protease from Bacillus subtilis at 50C for 3 days gave 6-O-vinyladipoyl-lactose (yield 35%). Poly(6-O-vinyladipoyl-lactose) with Mn = 21,200, Mw = 32,900, Mw/Mn = 1.56 could be obtained by chemical polymerization. Poly(vinyl alcohol) containing lactose branch was biodegradable. After 6 days in aqueous buffer (PH 7), this alkaline protease could degrade the polymer to an Mn of ca. 2100, Mw/Mn = 2.56.

Graft co-polymerization of maleic acid and vinyl acetate onto poly(vinylidene fluoride) powder by pre-irradiation technique

Binary monomers of maleic acid and vinyl acetate are grafted onto poly(vinylidene fluoride) (PVDF) powder by pre-irradiation induced graft polymerization technique in emulsion solution. The co-grafting of binary monomers is successfully proved by FT-IR spectroscopy analysis. The influences of the absorbed dose, reaction temperature, reaction time, total concentration of monomers, and feed ratio of binary monomers on the degree of grafting are investigated. The thermal property of grafted PVDF powder was characterized by differential scanning calorimetry (DSC) and thermo-gravimetry analysis (TGA).

Bifurcation control and eigenstructure assignment in continuous solution polymerization of vinyl acetate

The major difficulty in achieving good performance of industrial polymerization reactors lies in the lack of understanding of their nonlinear dynamics and the lack of well-developed techniques for the control of nonlinear processes, which are usually accompanied with bifurcation phenomenon. This work aims at investigating the nonlinear behavior of the parameterized nonlinear system of vinyl acetate polymerization and further modifying the bifurcation characteristics of this process via a washout filter-aid controller, with all the original steady state equilibria preserved. Advantages and possible extensions of the proposed methodology are discussed to provide scientific guide for further controller design and operation improvement.

RADICAL DESORPTION IN EMULSION POLYMERIZATION OF VINYL ACETATE

In the present paper a model equation for calculating the radical desorption rate constant,k0,in the emulsion polymerization of vinyl acetate was suggested and the various parameters forevaluating k0 were determined.Effects of reaction temperature,emulsifier concentration,initiator con-centration,monomer conversion and phase ratio on k0 were studied.It indicates that the desorptionof radicals from latex particles to aqueous phase must be taken into account in the modelling ofemulsion polymerization for the monomers with higher hydrophilicity such as vinyl acetate.

POLYMERIZATION OF ISOBUTYL VINYL ETHER CATALYSED BY DINUCLEAR HALF-TITANOCENES

Polymerization of isobutyl vinyl ether(IBVE)has been studied with mononuclear half-titanocene,CpTiCl_3[1]and dinuclear half-titanocenes,[(C_5H_4)_2(CH_2)_n][(TiCl_3)_2][2(n=3),3(n=6)],and[(C_5H_4)_2(CH_2)_n[(TiCl_2OR_2](R=2,6- diisopropylphenoxyl)[4(n=3),5(n=6)],in the presence of methyl aluminoxanes(MAO)as cocatalyst in methylene chloride.The influences of the length of polymethylene brigde and the substitution of aryloxy group at the metal center have been investigated at three polymerization temperature(...

Preparation of Macroporous Poly (vinyl alcohol-co-triallyl isocyanurate) Beads Bearing Aminocarboxylic Acid as Functional Groups by Suspension Polymerization

Macroporous poly (vinyl acetate-co-triallyl isocyanurate) beads were prepared with suspension polymerization method. The copolymer beads were then transformed into poly (vinyl alcohol-co-triallyl isocyanurate) by ester exchange reaction. Aminocarboxylic acids were immobilized on the copolymer beads by the esterification of hydroxyl groups with diethyl-lenetriaminepentaacetic bisanhydride. The weak acid exchange capacities, specific surface areas and mean pore diameters of the resultant resin beads were measured.

VINYL POLYMERIZATION OF NORBORNENE CATALYZED BY [2-(2-BENZIMIDAZOLYL)-6-((1-ARYLIMINOETHYL)PYRIDYL)]NICKEL CHLORIDE/MAO SYSTEM

The catalytic system of[2-(2-benzimidazolyl)-6-((1-aryliminoethyl)pyridyl)]nickel chloride/MAO(methylalu- minoxane)was found to be good active for vinyl polymerization of norbornene and provided polymers with relative narrow molecular distributions.Various reaction parameters,such as the ratios of nickel precursor to MAO or monomer norbornene, and the nature of the ligands in complexes were carefully investigated to realize their effects on the catalytic activities, polymer molecular weight and molecular we...

Kinetics of Vinyl Chloride Polymerization with Mixture of Initiators

Kinetic models for the rate constants of vinyl chloride polymerization in the presence of initiator mixtures were proposed. They may be used to design the initiator recipes for the vinyl chloride polymerization with uniform rate at different temperatures at which various grades of poly(vinyl chloride) will be prepared.

RADICAL POLYMERIZATION OF VINYL MONOMER INITIATED BY CERIC ION/TARTARIC ACID

The polymerization of acrylamide and acrylonitrile using ceric ion as initiator can be promoted greatly by the tartaric acid. The kinetics of acrylamide polymerization initiated by ceric ion/tartaric acid has been studied. The presence of the species of tartaric acid in Polyacrylonitrile produced by using ceric ion/tartaric acid as niitiator has been confirmed by FT-IR analysis.

Living/controlled polymerization of vinylpyridines into sequence-regulated copolymers by Lewis pair

The poly(vinylpyridine)(PVP) based(co)polymers are of particular interest in materials science, due to their multifunctionality and diverse applications. So far, there is no report on the sequence-regulated copolymerization of vinylpyridines(VPs) and methacrylate monomer in one-step manner yet. Here we designed and synthesized a series of guanidine phosphines as Lewis base(LB), which is combined with bulky organoaluminium to construct Lewis pairs(LPs) for polymerization of VPs. The living/controlled polymerization of 4-vinylpyridine(4-VP) or 2-vinylpyridine(2-VP) can be accomplished with remarkable efficiency by such Lewis pair polymerization(LPP), furnishing polymers with high molecular weight(up to 288 kg/mol) and narrow molecular weight distribution(as low as 1.17). Mechanistic studies reveal the interaction of LPs and formation of zwitterionic intermediates, providing solid evidences to support the proposed polymerization mechanism. More importantly, by simply adjusting the LA dosage, this LPP strategy realizes the unprecedented control over the sequence regulation of 2-VP-based copolymers from gradient to block in one-step manner, regardless of the monomer ratio, which greatly expands the versatility of the LPP.