Synthesis and Characterization of Novel Methacrylic Copolymers: Determination of Monomer Reactivity Ratios

A new methacrylic monomer, 4‐nitro‐3‐methylphenyl methacrylate (NMPM) was prepared by reacting 4‐nitro‐3‐methyl phenol dissolved in methyl ethyl ketone (MEK) in the presence of triethylamine as a catalyst. Copolymerization of NMPM with methyl methacrylate (MMA) has been carried out in methyl ethyl ketone (MEK) by free radical solution polymerization at 70±1°C utilizing benzoyl peroxide (BPO) as initiator. Poly (NMPM‐co‐MMA) copolymers were characterized by FT‐IR, ¹H‐NMR and ¹³C‐NMR spectroscopy. The molecular weights (M_w and M_n) and polydispersity indices (M_w/M_n) of the polymers were determined using a gel permeation chromatograph. The glass transition temperatures (T_g) of the copolymers were determined by a differential scanning calorimeter, showing that T_g increases with MMA content in the copolymer. Thermogravimetric analysis of the polymers, performed under nitrogen, shows that the stability of the copolymer increases with an increase in NMPM content. The solubility of the polymers was tested in various polar and non‐polar solvents. Copolymer compositions were determined by ¹H‐NMR spectroscopy by comparing the integral peak heights of well separated aromatic and aliphatic proton peaks. The monomer reactivity ratios were determined by the Fineman‐Ross (r₁ =7.090:r₂=0.854), Kelen‐Tudos (r₁=7.693: r₂=0.852) and extended Kelen‐Tudos methods (r₁=7.550: r₂= 0.856).     

Analysis of the end groups of poly(methyl methacrylate)

Methyl methacrylate polymerization by potassium hydride results in macromolecules with the methyl starting group. A side-reaction occurs during the process leading to potassium methoxide. It serves as the second initiator of the polymerization and gives macromolecules with the methoxy starting group. All macromolecules possess the methine group at the chain end after protonation. Potassium alkalide K⁻, K⁺(15-crown-5)₂ produces various active centres in the initial step of the polymerization. It results in macromolecules with the methyl, ethyl, methoxy and vinyl ether starting groups. However, the majority of macromolecules are formed on the species with two active centres. The termination reaction takes place during the polymerization, therefore, not all chains have the methine end group after protonation.     

Synthesis and kinetics of polymerization of acrylic and methacrylic monomers containing 1,3-dioxane groups in their structure

(5-Ethyl-1,3-dioxane-5-yl) methyl acrylate (HEDA) and (5-ethyl-1,3-dioxane-5-yl)methyl methacrylate (HEDMA) were synthesized by reaction between acryloyl and methacryloyl chloride with 5-ethyl, 5-hydroxymethyl, 1,3-dioxane. The kinetics of the polymerization of both are studied at different temperatures in benzene solution. Dilatometric techniques and nonlinear least-squares methods were used to obtain the kinetic data and to determine the kinetic constants, respectively. The values of k_p/k^1/2_t for the acrylic and methacrylic monomers are higher than those corresponding to methyl acrylate and methyl methacrylate, respectively. Important changes in k_p/k^1/2_t with temperature occur in the polymerization of HEDA, and the corresponding Arrhenius plot gives an activation energy of 5.6 kcal mol⁻¹. On the contrary, only slight changes with temperature are observed in this ratio for HEDMA and the activation energy associated with the polymerization reaction is ca. 1.7 kcal mol⁻¹. The stereo-structure of both polymers was determined by ¹³C-NMR spectroscopy and the molar fractions of tactic dyads, triads (and in the case of the methacrylic polymer also pentads) were determined from different resonance signals. Finally, the glass transition temperatures of both PHEDA and PHEDMA are 33 and 123°C, respectively. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1125–1132, 1997     

Synthesis and properties of polydimethylsiloxane-containing block copolymers via living radical polymerization

Polydimethylsiloxane (PDMS) block copolymers were synthesized by using PDMS macroinitiators with copper-mediated living radical polymerization. Diamino PDMS led to initiators that gave ABA block copolymers, but there was low initiator efficiency and molecular weights are somewhat uncontrolled. The use of mono- and difunctional carbinol–hydroxyl functional initiators led to AB and ABA block copolymers with narrow polydispersity indices (PDIs) and controlled number-average molecular weights (M_n's). Polymerization with methyl methacrylate (MMA) and 2-dimethylaminoethyl methacrylate (DMAEMA) was discovered with a range of molecular weights produced. Polymerizations proceeded with excellent first-order kinetics indicative of living polymerization. ABA block copolymers with MMA were prepared with between 28 and 84 wt % poly(methyl methacrylate) with M_n's between 7.6 and 35 K (PDI <1.30), which show thermal transitions characteristic of block copolymers. ABA block copolymers with DMAEMA led to amphiphilic block copolymers with M_n's between 9.5 and 45.7 K (PDIs of 1.25–1.70), which formed aggregates in solution with a critical micelle concentration of 0.1 g dm⁻³ as determined by pyrene fluorimetry experiments. Monocarbinol functional PDMS gave AB block copolymers with both MMA and DMAEMA. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1833–1842, 2001     

Study on soap‐free P(MMA‐EA‐AA or MAA) latex particles with narrow size distribution

Soap‐free poly(methyl methacrylate‐ethyl acrylate‐acrylic acid or methacrylic acid) [P(MMA‐EA‐AA or MAA)] particles with narrow size distribution were synthesized by seeded emulsion polymerization of methyl methacrylate (MMA), ethyl acrylate (EA) and acrylic acid (AA) or methacrylic acid (MAA), and the influences of the mass ratio of core/shell monomers used in the two stages of polymerization ([C/S]_w) and initiator amount on polymerization, particle size and its distribution were investigated by using different monomer addition modes. Results showed that when the batch swelling method was used, the monomer conversion was more than 96.0% and particle size distribution was narrow, and the particle size increased first and then remained almost unchanged at around 600 nm with the [C/S]_w decreased. When the drop‐wise addition method was used, the monomer conversion decreased slightly with [C/S]_w decreased, and large particles more than 750 nm in diameter can be obtained; with the initiator amount increased, the particle size decreased and the monomer conversion had a trend to increase; the particle size distribution was broader and the number of new particles was more in the AA system than in the MAA system; but the AA system was more stable than the MAA system at both low and high initiator amount. Copyright © 2006 John Wiley & Sons, Ltd.     

Specific Features of <Emphasis Type="Italic">N</Emphasis>-Morpholinoethyl Methacrylate Synthesis

Methods for synthesis of N-morpholinoethyl methacrylate were compared. It was shown that the monomer produced by acylation of N-morpholinoethanol with methacrylic acid anhydride or methacryloyl chloride spontaneously polymerizes in storage. The possible reasons for the spontaneous polymerization of N-morpholinoethyl methacrylate produced by the acylation method were considered. The conditions in which a stable-in-storage monomer can be obtained in 86–88% yield by the method of re-esterification of methyl methacrylate with N-morpholinoethanol were determined.     

METHACRYLOYL DERIVITIZED HYPERBRANCHED POLYESTER. 1. SYNTHESIS,CHARACTERIZATION, AND COPOLYMERIZATION

Three hyperbranched multi-methacrylates (H20-MMA, H30-MMA and H40-MMA) have been synthesized by reacting Boltorn dendritic polyols with methacrylic anhydride and methacryloyl chloride. Their structures were characterized by FT-IR and NMR (¹H and ¹³C) and molecular weights were measured by GPC. These multi-methacrylates (H-MMAs) mixed well with a variety of monomers such as acrylic acid (AA), methacrylic acid (MA), methyl methacrylate (MMA), 2-hydroxy-ethyl methacrylate (HEMA), tri(ethylene glycol) dimethdimethacrylate (TEGDMA), and bisphenol A glycidyl dimethacrylate (BisGMA). The initial studies on thermal polymerization activities of 10% of H-MMAs with AA, MA, and MMA showed that they gave higher polymerization enthalpy than the corresponding homopolymerization. The resulting materials showed one glass transition temperature, indicating a typical single-phase resin. The H-MMAs can effectively copolymerize with AA, MA, and MMA, with essentially no homopolymers produced, as indicated by acetone extraction studies. This indicated that the hyperbranched multi-methacrylates have the potential to be used as crosslinking agents or modifiers with a number of monomers to produce new thermosets.     

Vinyl polymerization. 416. Polymerization of vinyl monomer initiated by polyethyleneglycol

The polymerization of vinyl monomer initiated by polyethyleneglycol (PEG) in aqueous solution was carried out at 85°C with shaking. Acrylonitrile (AN), methyl methacrylate (MMA), and methacrylic acid were polymerized by PEG–300 (M?_n = 300), whereas styrene was not. The effects of the amounts of monomer and PEG, the molecular weight of PEG, and the hydrophobic group at the end of PEG molecule on the polymerization were studied. The selectivity of vinyl monomer and the effect of the hydrophobic group are discussed according to “the concept of hard and soft hydrophobic areas and monomers.” The kinetics of the polymerization was investigated. The overall activation energy in the polymerization of AN was estimated as 37.9 kJ mol^?1. The polymerization was effected by a radical mechanism.     

Sulfur-Containing Vinyl Monomers. XV. Kinetic Study of Radical Polymerization of Vinyl Mercaptobenzothiazole and Its Copolymerization

A kinetic study of radical polymerization of vinyl mercaptobenzothiazole (VMBT) with α,α′-azobisisobutyonitrile (AIBN) at 60°C was carried out. The rate of polymerization (R_p) was found to be expressed by the rate equation: R_p = k[AIBN]^0.5 [VMBT]^1.0, indicating that the polymerization of this monomer proceeds via an ordinary radical mechanism. The apparent activation energy for overall polymerization was calculated to be 20.9 kcal/mole. Moreover, this monomer was copolymerized with methyl methacrylate, acrylonitrile, vinyl acetate, phenyl vinyl sulfide, maleic anhydride, and fumaronitrile at 60°C. From the results obtained, the copolymerization parameters were determined and discussed.     

Synthesis and characterization of nano-sized poly[(butyl acrylate)-co-(methyl methacrylate)-co-(methacrylic acid)] latex via differential microemulsion polymerization

Poly[(butyl acrylate)-co-(methyl methacrylate)-co-(methacrylic acid)] latex particles were synthesized via differential microemulsion polymerization. The effect of initiator type and methacrylic acid incorporation were investigated. The initiator type could significantly affect the particle size and the molecular weight of the resulting polymer and 2,2′-azobisisobutyronitrile produced the smallest particle size. The incorporation of methyl methacrylate (MAA) in the copolymer and terpolymer structures was confirmed by FTIR and NMR spectroscopy, and DSC in that the carbonyl peak of carboxylic acid at 1,700 cm^?1 in the FTIR spectrum was observed when the MAA amount was high enough, the peak areas at 0.9 ppm in the NMR spectrum confirmed the participation of MAA from the increasing proton signals and the glass transition temperature and polarity of the polymer increased when the MAA amount was increased. This supported that the MAA was incorporated into the polymer chains. MAA was found to produce a vitrification effect during the polymerization.     

Effect of valence state of vanadium on stereoblock polymerization of methyl methacrylate with VOCl3–AlEt2Br catalyst system

The polymerization of methyl methacrylate with the VOCL₃–ALEt₂Br catalyst system in n-hexane has been studied. The first-order dependence of rate of polymerization on catalyst and monomer concentrations, activation energy of 6.67 kcal/mole, and NMR spectra of polymer lend support to a coordinate anionic mechanism of polymerization. It has been shown that the vanadium in V⁺² oxidation state is less active than V⁺³ oxidation state of active complex.     

Polymerization and copolymerization of α-alkylacrylic acids and characterization of their polymers

α-Alkylacrylic acids (RAA's) bearing n-alkyl groups were found to homopolymerize with slower rates than acrylic and methacrylic acids to number-average molecular, weight (M?_n) of 10⁴ or above. When the α-substituent was a branched alkyl group, the polymerization rate and M?_n decreased further. Reactivities of RAA's in copolymerization were interpreted by steric and resonance effects of the alkyl group using Hancock's steric substituent constant. Comparison of the reactivities of RAA's with those of methyl α-alkylacrylates revealed that replacement with the smaller carboxyl group facilitates polymerization and copolymerization. Preference of co-syndiotactic propagation in the copolymerization of methacrylic acid with styrene changed to random fashion in the copolymerization of the α-higher alkyl derivatives. After methylation with diazomethane, the homopolymers were shown to be thermally less stable than poly(methyl methacrylate). T_g's of poly(methyl α-ethylacrylate) and poly(methyl α-n-propylacrylate) were 57 and 25°C, respectively.     

Polymerization of methyl methacrylate with ceric ion-methanol redox system

The polymerization of methyl methacrylate initiated by Ce⁴⁺ methanol redox system was studied in aqueous solution of nitric acid at 15°C. The polymerization was initiated by primary radicals formed from Ce⁴⁺/alcohol complex. Poly(methyl methacrylate) chains containing the alcohol residue were obtained. Variations in the temperatuare and concentration of the components of the redox system allowed the control of the rate of polymerization and molecular weight of the polymer. The concentration of the hydroxyl end groups in the poly(methyl methacrylate) of low molecular weight was determined by titration and by spectrometric method.     

Role of dimethyl sulfoxide as a solvent for vinyl polymerization

Dimethyl sulfoxide has been used as a solvent in the polymerization of methyl methacrylate and styrene. The chain-transfer coefficients of the solvent and the values of δ [i.e., (2k_t)^1/2/k_p] in solvent-monomer mixtures of various compositions were determined. δ was observed to be dependent on the solvent concentration in the case of methyl methacrylate but remained constant in case of styrene. The lowering of the values of δ with increasing solvent concentration in case of methyl methacrylate has been attributed to an interaction between the solvent and poly(methyl methacrylate) radical resulting in lower termination rate.     

Preparation and characterization of graft terpolymers with controlled molecular structure

Segmented terpolymers, poly(alkyl methacrylate)‐g‐poly(D ‐lactide)/poly(dimethylsiloxane) (PLA/PDMS), were prepared with a combination of the “grafting through” technique (macromonomer method) and controlled/living radical polymerization (atom transfer radical polymerization or reversible addition–fragmentation transfer polymerization). Two synthetic pathways were used. The first was a single‐step approach in which a low‐molecular‐weight methacrylate monomer (methyl methacrylate or butyl methacrylate) was copolymerized with a PLA macromonomer and a PDMS macromonomer. The second strategy was a two‐step approach in which a graft copolymer containing one macromonomer was chain‐extended by a copolymerization of the second macromonomer and the low‐molecular‐weight methacrylate. The kinetics of both synthetic approaches were investigated, showing that the polymerizations exhibited a controlled/living behavior. Furthermore, the molecular structure of the terpolymers (composition, molecular weight distribution, and microstructure) was investigated by two‐dimensional liquid chromatography. Well‐defined terpolymers with controlled branch distribution, composition (F_w,PMMA/F_w,PLA/F_w,PDMS ～ 50/30/20) molecular weight (M_n ～ 50,000 g · mol^?1), and a narrow molecular weight distribution (M_w/M_n ～ 1.3) were prepared via both pathways. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1939–1952, 2004     

Reverse Atom Transfer Radical Polymerization of MMA in the Presence of CaCO3/SiO2 Two-Component Composite Particles

Summary: We previously discovered that structurally well-defined polymer/inorganic composite particles, i.e., poly(methyl methacrylate) (PMMA)/CaCO₃/SiO₂ three-component composite particles, can be achieved via reverse atom transfer radical polymerization (ATRP), using 2,2′-azo-bis-isobutyronitrile as initiator and Cu^II bromide as catalyst. In the present study, the influence of the mass ratio of CaCO₃/SiO₂ two-component composite particles to methyl methacrylate (MMA) on the rate and behavior of the polymerization was studied in detail. The results illustrate that increasing the mass ratio of CaCO₃/SiO₂ two-component composite particles will decrease the overall rate of polymerization of MMA under standard reverse ATRP conditions. Thermal properties of the obtained well-defined particles were characterized and determined by thermogravimetric analysis (TGA). The results indicate that well-defined PMMA chains grafted on the surface of CaCO₃/SiO₂ particles were only degraded by random chain scission of C C linkages within the PMMA chain, which is different from the degradation of PMMA chains prepared via traditional radical polymerization. This difference is reasonably ascribed to the difference between the end groups of PMMA prepared via reverse ATRP and that via traditional radical polymerization, which has been confirmed by end group analysis measured by ¹H–NMR spectroscopy.     

Timolol maleate release from pH-sensible poly(2-hydroxyethyl methacrylate-co-methacrylic acid) hydrogels

Multifunctional polymeric materials were obtained from poly(methacrylic acid-co-2-hydroxyethyl methacrylate), to be used as a raw material in the manufacture of contact lens and as drug delivery systems. Poly(methacrylic acid-co-2-hydroxyethyl methacrylate) was prepared by free-radical polymerization in aqueous solution at 60 °C using potassium persulfate (KPS) as initiator and N,N^′-methylenebisacrylamide (BIS) as cross-linker agent. The dynamic and equilibrium swelling properties of dry glassy poly(methacrylic acid-co-2-hydroxyethyl methacrylate) polymeric networks were studied as a function of pH and methacrylic acid (MAA) content. The water content increase as MAA content and pH increase. Timolol maleate delivery from poly(MAA) and poly(2-hydroxyethyl methacrylate) (HEMA) homopolymers was studied and the results show a Fickian diffusion behavior.     

Homopolymer and copolymers of 4-nitro-3-methylphenyl methacrylate with glycidyl methacrylate: Synthesis, characterization, monomer reactivity ratios and thermal properties

The novel methacrylic monomer, 4-nitro-3-methylphenyl methacrylate (NMPM) was synthesized by reacting 4-nitro-3-methylphenol dissolved in ethyl methyl ketone (EMK) with methacryloyl chloride in the presence of triethylamine as a catalyst. The homopolymer and copolymers of NMPM with glycidyl methacrylate having different compositions were synthesized by free radical polymerization in EMK solution at 70 ± 1 °C using benzoyl peroxide as free radical initiator. The homopolymer and the copolymers were characterized by FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The solubility tests were tested in various polar and non-polar solvents. The molecular weight and polydispersity indices of the copolymers were determined using gel permeation chromatography. The glass transition temperature of the copolymers increases with increase in NMPM content. The thermogravimetric analysis of the polymers performed in air showed that the thermal stability of the copolymer increases with NMPM content. The copolymer composition was determined using ¹H NMR spectra. The monomer reactivity ratios were determined by the application of conventional linearization methods such Fineman-Ross (r₁ = 1.862, r₂ = 0.881), Kelen-Tudos (r₁ = 1.712, r₂ = 0.893) and extended Kelen-Tudos methods (r₁ = 1.889, r₂ = 0.884).     

Immobilized copper catalyst for atom transfer radical addition and polymerization

A novel multidentate amine grafted on silica gel and magnetic microsphere was prepared. Its chemical structure was confirmed by C¹³ NMR, XPS and FTIR, and the nitrogen content was determined by elemental analysis. It was also used as a ligand for CuCl and successfully catalyzed the atom transfer radical addition of both carbon tetrachloride (CCl₄) to methyl methacrylate and methyl trichloroacetate to styrene, repeatedly. The conversion and purity of the product were determined through gas chromatography and ¹H NMR, respectively. The immobilized copper catalyst complex was also used in atom transfer radical polymerization of styrene initiated by 1,1,1,3‐tetrachloro‐3‐phenylpropane and methyl methacrylate initiated by methyl 2‐methyl‐2,4,4,4‐tetrachlorobutyrate, respectively. Although the polymerization took place successfully, it did not proceed in a controlled fashion. Copyright © 2010 John Wiley & Sons, Ltd.     

Radical copolymerization of acrylic monomers. IV. Effect of substituents on the radical polymerization and copolymerization of phenyl acrylates

The kinetics of radical polymerization of phenyl, ortho-chlorophenyl, and para-chlorophenyl acrylates, as well as their copolymerization with methyl methacrylate, have been studied dilatometrically. The results obtained indicate that the overall rate of polymerization is affected by the flexibility of the growing radicals. However, the copolymerization of these monomers with methyl methacrylate gives overall rates rather similar for all three systems, being fundamentally regulated by the formation of reversible π complexes between the donor aromatic rings and the acceptor methacrylic double bonds. Dilatometric methods for the study of the copolymerization reactions have been tested and the corresponding binary bonding frequencies B_ij and conversion factors K_ij have been calculated for the copolymerization of ortho- and para-chlorophenyl acrylates with methyl methacrylate.