Conventional and RAFT radical copolymerizations of β‐pinene with N‐substituted maleimides

The feasibility of the radical copolymerizations of β‐pinene with three N‐substituted maleimides, i.e. N‐phenylmaleimide (PhMI), N‐methylmaleimide (MeMI), and N‐ethylmaleimide (EtMI), was clarified for the first time. The copolymerization rates decreased in the order PhMI > MeMI > EtMI. A marked penultimate effect on the activity of the N‐substituted maleimide‐terminated radicals was found in these copolymerizations. The penultimate monomer reactivity ratios evaluated by the nonlinear method were r₁ = 0.10, r′₁ = 8.30, r₂ = r′₂ = 0 for PhMI–β‐pinene, r₁ = 0.20, r′₁ = 7.09, r₂ = r′₂ = 0 for MeMI–β‐pinene, and r₁ = 0.16, r′₁ = 6.50, r₂ = r′₂ = 0 for EtMI–β‐pinene. Furthermore, the possible controlled copolymerizations of β‐pinene and N‐substituted maleimides were then attempted via the reversible addition‐fragmentation chain transfer (RAFT) technique. In the presence of RAFT agent 1‐phenylethyl phenyldithioacetate, the copolymerization of β‐pinene with MeMI or EtMI was retarded severely. However, much smaller retardation was observed in the RAFT copolymerization of β‐pinene with PhMI, and, more importantly, the copolymerization exhibited typical features of a controlled system. The solvent effect on the RAFT copolymerization of β‐pinene and PhMI was also investigated using matrix‐assisted laser desorption ionization time‐of‐fight mass spectrometry (MALDI‐TOF‐MS) analysis. The results clearly indicated that copolymerization in tetrahydrofuran suffered from competitive transfer and termination side‐reactions arising from the solvent in spite of the presence of the RAFT agent. Copyright © 2007 Society of Chemical Industry     

Synthesis and properties of gradient copolymers of butyl methacrylate and fluorinated acrylate via RAFT miniemulsion copolymerizations

A series of gradient fluorinated copolymers with a broad variation of the monomer units in the polymer chain were synthesized via semibatch CPDB‐mediated RAFT miniemulsion polymerization technique. In the presence of RAFT agent 2‐cyanoprop‐2‐yl dithiobenzoate (CPDB), the copolymerization of BMA and FMA in miniemulsion exhibited typical features of a controlled molecular weights and narrow polydispersities. The macromolecular structure and thermal behavior of the synthesized fluorinated copolymers were investigated in detail. The DSC analyses show that the gradient copolymers showed a unique thermal behavior with broad range of transition temperature. It was also confirmed that the fluorinated gradient copolymer exhibited obvious surface segregation structure and ultra‐low surface energy between 16.8 and 20.3 mN/m. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42936.     

Reversible addition fragmentation chain transfer copolymerization: influence of the RAFT process on the copolymer composition

Reversible addition fragmentation chain transfer (RAFT) mediated and conventional copolymerizations at low monomer conversions have been carried out for the systems methyl methacrylate (MMA)-styrene, methyl acrylate (MA)-styrene and methyl methacrylate-butyl acrylate (BA). The polymer samples have been analyzed via ¹H-NMR spectroscopy to obtain the copolymer composition and the terminal model reactivity ratios. In the RAFT mediated copolymerizations, the polymer mole fraction of the monomer with the larger reactivity ratio is increased compared to the conventional copolymerization. Simulations have been carried out using the program package PREDICI^® to examine possible explanations for the experimental findings. The simulations demonstrate that the RAFT process itself may alter the macroradical populations and the copolymer composition by offering additional reaction pathways. Further, the rate coefficients for the initiation reaction and the pre-equilibrium play an important role in determining the copolymer composition. The rate coefficients governing the main equilibrium of the RAFT process have only a minor impact on the copolymer composition.     

Determination of monomer reactivity ratios using in situ FTIR spectroscopy for maleic anhydride/norbornene‐free‐radical copolymerization

Monomer reactivity ratios for maleic anhydride (MAH) and norbornene (Nb) free‐radical copolymerizations were estimated by using a linear graphical method, which is based upon the terminal model developed by Mayo and Lewis. Reactions were performed by using optimized reaction conditions that were previously determined. MAH/Nb copolymerizations (3 mol % AIBN initiator, 60% solids in THF, 65°C, 24 h). Copolymerization data were collected via in situ FTIR to low degrees of conversion (～ 10%) for copolymerizations of MAH and Nb. The following five different MAH/Nb comonomer feed molar ratios were analyzed: 40/60, 45/55, 50/50, 55/45, and 60/40. Conversion data that were measured with in situ FTIR were employed in the rearranged copolymer composition equation to estimate MAH and Nb reactivity ratios. Both of the reactivity ratios were determined to be near 0 (r_MAH = 0.02, r_Nb = 0.01), which was indicative of an alternating copolymerization mechanism. The highest observed rate constant for copolymerization was obtained at an equal molar concentration of monomers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3240–3246, 2004     

Free radical copolymerization of N,N‐dimethylaminoethyl methacrylate with styrene and methyl methacrylate: monomer reactivity ratios and glass transition temperatures

BACKGROUND: The properties of copolymers depend strongly on their composition; therefore in order to tailor some for specific applications, it is necessary to control their synthesis, and, in particular, to know the reactivity ratios of their constituent monomers. Free radical copolymerizations of N,N‐dimethylaminoethyl methacrylate (DMAEM) with styrene (ST) and methyl methacrylate (MMA) in toluene solution using 1‐di(tert‐butylperoxy)‐3,3,5‐trimethylcyclohexane as initiator at 70 °C were investigated. Monomer reactivity ratios were determined for low conversions using both linear and nonlinear methods. RESULTS: For the DMAEM/ST system the average values are r₁ = 0.43 and r₂ = 1.74; for the DMAEM/MMA system the average values are r₁ = 0.85 and r₂ = 0.86. The initial copolymerization rate, R_p, for DMAEM/ST sharply decreases as the content of ST in the monomer mixture increases up to 30 mol% and then attains a steady value. For the DMAEM/MMA copolymerization system the composition of the feed does not have a significant influence on R_p. The glass transition temperatures (T_g) of the copolymers were determined calorimetrically and calculated using Johnston's sequence length method. A linear dependence of T_g on copolymer composition for both systems is observed: T_g increases with increasing ST or MMA content. CONCLUSION: Copolymerization reactivity ratios enable the design of high‐conversion processes for the production of copolymers of well‐defined properties for particular applications, such as the improvement of rheological properties of lubricating mineral oils. Copyright © 2009 Society of Chemical Industry     

Atom transfer radical homo‐ and copolymerization of styrene and methyl acrylate initiated with trichloromethyl‐ terminated poly(vinyl acetate) macroinitiator: A kinetic study

Atom transfer radical bulk copolymerization of styrene (St) and methyl acrylate (MA) initiated with trichloromethyl‐terminated poly(vinyl acetate) macroinitiator was performed in the presence of CuCl/PMDETA as a catalyst system at 90°C. Linear dependence of ln[M]₀/[M] versus time data along with narrow polydispersity of molecular weight distribution revealed that all the homo‐ and copolymerization reactions proceed according to the controlled/living characteristic. To obtain more reliable monomer reactivity ratios, the cumulative average copolymer composition at moderate to high conversion was determined by ¹H‐NMR spectroscopy. Reactivity ratios of St and MA were calculated by the extended Kelen‐Tudos (KT) and Mao‐Huglin (MH) methods to be r_St = 1.018 ± 0.060, r_MA = 0.177 ± 0.025 and r_St = 1.016 ± 0.053, r_MA = 0.179 ± 0.023, respectively, which are in a good agreement with those reported for the conventional free‐radical copolymerization of St and MA. Good agreement between the theoretical and experimental composition drifts in the comonomer mixture and copolymer as a function of the overall monomer conversion were observed, indicating that the reactivity ratios calculated by copolymer composition at the moderate to high conversion are accurate. Instantaneous copolymer composition curve and number‐average sequence length of comonomers in the copolymer indicated that the copolymerization system tends to produce a random copolymer. However, MA‐centered triad distribution results indicate that the spontaneous gradient copolymers can also be obtained when the mole fraction of MA in the initial comonomer mixture is high enough. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Homopolymerization and copolymerization of tert‐butyl methacrylate and norbornene with nickel‐based methylaluminoxane catalysts

The homopolymerization and copolymerization of tert‐butyl methacrylate (tBMA) and norbornene (NB) with nickel(II) acetylacetonate in combination with methylaluminoxane were systematically investigated. This catalytic system showed high activity toward the homopolymerization of both NB and tBMA. For these copolymerizations, activity was gradually lost with an addition of tBMA to NB or of NB to tBMA. This result was qualitatively explained with the trigger coordination mechanism. Furthermore, the determination of the reactivity ratios indicated a significantly higher reactivity for NB than for tBMA (r_NB = 4.14 and r_tBMA = 0.097), and this was interpreted by the coordination mechanism. The synthesized acrylate/NB copolymers exhibited glass‐transition temperatures of 100–250°C. The absence of crystallinity and the homogeneous repartition of the monomer units along the main chain yielded products with high transparency and high stability © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1824–1833, 2004     

Synthesis and characterization of functional copolymers of citronellol with butylmethacrylate initiated by benzoyl peroxide

Benzoyl peroxide (BPO)‐initiated free radical copolymerization of citronellol with butylmethacrylate (BMA) in xylene at 80°C ± 0.1°C under the inert atmosphere of nitrogen has been studied. The kinetics expression is R_p α [I]^0.5±0.27 [citronellol]^1.0±0.13 [BMA]^1.0±0.18. The overall activation energy has been calculated as 65 kJ/mol. Bands at 3436 and 1732 cm^?1 in the FTIR spectrum of the copolymer(s) have indicated the presence of hydroxy, ester group of citronellol and butylmethacrylate, respectively. The ¹H‐NMR spectrum shows peaks at 7.0–7.7 δ due to ? OH proton of citronellol and at 3.2–4.0 δ due to ? OCH₂ proton of butylmethacrylate. The molecular weight M_v and η_int of the copolymers have been measured with the help of gel permeation chromatography in tetrahydrofuran at 25°C to calculate Mark‐Houwink constants as K = 2.68 × 10^?4 and α = 0.34 ± 0.40. The alternating nature of the copolymer is confirmed by reactivity ratios r₁ (BMA) = 0.023 ± 0.004 and r₂ (Citronellol) = 0.0025 ± 0.22. The Alfrey‐Price Q‐e parameters for citronellol have been calculated as Q₂ = 0.13 and e₂ = –1.28. Thermal decompositions of copolymer are evaluated with the help of thermal gravimetric analysis technique. The mechanism of copolymerization has been elucidated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of methyl methacrylate/styrene hyperbranched copolymers via living radical mechanism

Free‐radical copolymerizations of N,N‐diethylaminodithiocarbamoylmethylstyrene (inimer: DTCS) with a methyl methacrylate (MMA)/zinc chloride (ZnCl₂) complex were carried out under UV light irradiation. DTCS monomers play an important role in this copolymerization system as an inimer that is capable of initiating living radical polymerization of the vinyl group. The reactivity ratios (r₁ = 0.56 and r₂ = 0.52: DTCS [M₁]; MMA [M₂]) obtained for this copolymerization system were different from a corresponding model system (alternating copolymer) of a styrene and MMA/ZnCl₂ complex (r₁ = 0.25 and r₂ = 0.056). It was found that the hyperbranched copolymers produced exhibited a random branching structure. It was found that the Lewis acid ZnCl₂ formed the complex not only with MMA but also with the carbamate group of inimer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2490–2495, 2003     

Determination of monomer reactivity ratios for copolymerizations of methacrylic acid with poly (ethylene glycol) monomethacrylate

Self-associating copolymers of methacrylic acid (MAA) with poly (ethylene glycol) monomethacrylate (PEGMA) were prepared by free radical copolymerization of MAA with PEGMA using dispersion polymerization in D₂O, or solution polymerization in a 50/50 ethanol–D₂O mixture. These copolymers have been studied as components of reversible hydrogels¹ and in medical applications.² In order to understand the relationship between the copolymer structure and its performance, it is important to determine the sequence distribution of the copolymer. The copolymer architecture is determined by the reactivity ratios and integrated instantaneous feed compositions. The reactivity ratios were determined using the first-order Markov method³ by running a series of reactions at various initial monomer ratios and determining the monomer incorporation into the copolymer as a function of time, via ¹H nuclear magnetic resonance. The reactivity ratios for dispersion copolymerizations of MAA with PEGMA in water were determined to be r₁ = 1.03 and r₂ = 1.02, whereas solution copolymerization in 50/50 EtOH–H₂O gave reactivity ratios of r₁ = 2.0 and r₂ = 3.6. These results show that the reactivity ratios and copolymer architecture are influenced by the solvent system. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1019–1025, 1998     

Monomer reactivity ratios for acrylonitrile/ammonium itaconate during aqueous‐deposited copolymerization initiated by ammonium persulfate

Monomer reactivity ratios of acrylonitrile/ammonium itaconate during aqueous‐deposited copolymerization initiated by ammonium persulfate were investigated. Kelen–Tudos method was used to examine the reactivity ratios. It was shown that the reactivity ratios were influenced by the conversions and temperatures of copolymerization. The reactivity ratios in aqueous‐deposited copolymerization system were similar to those in the solution polymerization system at polymerization conversions of less than 5% [reactivity ratio of acrylonitrile (r₁) 0.842 ± 0.02, reactivity ratio of ammonium itaconate (r₂) = 3.624 ± 0.02]. The reactivity ratio of AN rises and that of (NH₄)₂IA decreases, when the polymerization conversion increases till 13%. Aqueous‐deposited copolymerization initiated by AIBN was also studied. It was found that some polymers were formed in water phase and the monomers had different reactivity ratios by comparison with those initiated by ammonium persulfate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4645–4648, 2006     

Reactivity ratios and copolymer properties of 2‐(diisopropylamino)ethyl methacrylate with methyl methacrylate and styrene

Free radical copolymerization kinetics of 2‐(diisopropylamino)ethyl methacrylate (DPA) with styrene (ST) or methyl methacrylate (MMA) was investigated and the corresponding copolymers obtained were characterized. Polymerization was performed using tert‐butylperoxy‐2‐ethylhexanoate (0.01 mol dm^?3) as initiator, isothermally (70 °C) to low conversions (<10 wt%) in a wide range of copolymer compositions (10 mol% steps). The reactivity ratios of the monomers were calculated using linear Kelen–Tüd?s (KT) and nonlinear Tidwell–Mortimer (TM) methods. The reactivity ratios for MMA/DPA were found to be r₁ = 0.99 and r₂ = 1.00 (KT), r₁ = 0.99 and r₂ = 1.03 (TM); for the ST/DPA system r₁ = 2.74, r₂ = 0.54 (KT) and r₁ = 2.48, r₂ = 0.49 (TM). It can be concluded that copolymerization of MMA with DPA is ideal while copolymerization of ST with DPA has a small but noticeable tendency for block copolymer building. The probabilities for formations of dyad and triad monomer sequences dependent on monomer compositions were calculated from the obtained reactivity ratios. The molar mass distribution, thermal stability and glass transition temperatures of synthesized copolymers were determined. Hydrophobicity of copolymers depending on the composition was determined using contact angle measurements, decreasing from hydrophobic polystyrene and poly(methyl methacrylate) to hydrophilic DPA. Copolymerization reactivity ratios are crucial for the control of copolymer structural properties and conversion heterogeneity that greatly influence the applications of copolymers as rheology modifiers of lubricating oils or in drug delivery systems. © 2015 Society of Chemical Industry     

Radical copolymerization of maleic anhydride and substituted styrenes by reversible addition-fragmentation chain transfer (RAFT) polymerization

Reversible addition fragmentation transfer (RAFT) copolymerization with benzyl dithiobenzoate (BDTB) as chain transfer agent was used to copolymerize maleic anhydride (MA) with styrene (St) and with the substituted styrenes p-chlorostyrene (pClSt), p-methoxystyrene (pMeOSt) and p-methylstyrene (pMeSt). Kinetic studies indicated that radical copolymerizations proceeded with apparent ‘living’ character, deduced from experiments demonstrating an increase in molar mass with monomer conversion, narrow molar mass distribution and chain extension to form block copolymer. All copolymers were alternating in chain structure as confirmed by determinations of monomer reactivity ratios. The degree of control in the RAFT mechanism and the establishment of the fragmentation equilibrium incorporating MA are discussed for styrene and for p-substituted styrenes, in relation to experimental copolymerizations producing molar masses somewhat higher than expected. For copolymerizations of MA with α-methylstyrene (αMeSt), conventional rather than controlled behaviour was observed, suggesting that the fragmentation equilibrium could be shifted towards the αMeSt propagating radical.     

Metathesis copolymerization of chlorine-containing acetylenes with NBE catalyzed by MoCl5-n-Bu4Sn

Summary In the copolymerizations of 1-chloro-1-octyne (ClOc) and 1-chloro-2-phenylacetylene (ClPA) with norbornene (NBE) by MoCl₅-n-Bu₄Sn in toluene at-20°C, both comonomers were consumed simultaneously. The GPC curves of the copolymerization products were unimodal and identical irrespective of the RI and UV (290 nm) detectors. The¹³C NMR spectra of the products exhibited the presence of cross-propagating sequences. From these results, it is concluded that the copolymerization products are copolymers and not mixtures of homopolymers. The monomer reactivity ratios were: r_ClOc=0.69, r_NBE=6.4; r_ClPA=1.0, r_NBE=3.1. The more electron-donating the ring substituent of CiPA, the more reactive the ClPA in copolymerization with NBE.     

Synthesis,characterization, and reactivity ratios of copolymers derived from 4‐nitrophenyl acrylate and n‐butyl methacrylate

Free‐radical copolymerization of 4‐nitrophenyl acrylate (NPA) with n‐butyl methacrylate (BMA) was carried out using benzoyl peroxide as an initiator. Seven different mole ratios of NPA and BMA were chosen for this study. The copolymers were characterized by IR, ¹H‐NMR, and ¹³C‐NMR spectral studies. The molecular weights of the copolymers were determined by gel permeation chromatography and the weight‐average (M _w) and the number‐average (M _n) molecular weights of these systems lie in the range of 4.3–5.3 × 10⁴ and 2.6–3.0 × 10⁴, respectively. The reactivity ratios of the monomers in the copolymer were evaluated by Fineman–Ross, Kelen–Tudos, and extended Kelen–Tudos methods. The product of r₁, r₂ lies in the range of 0.734–0.800, which suggests a random arrangement of monomers in the copolymer chain. Thermal decomposition of the polymers occurred in two stages in the temperature range of 165–505°C and the glass transition temperature (T_g) of one of the systems was 97.2°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1817–1824, 2003     

Monomer apparent reactivity ratios for acrylonitrile/ammonium itaconate radical copolymerization systems

Ammonium itaconate was first used to copolymerize with acrylonitrile. This was achieved by using azobisisobutyronitrile as the initiator and dimethyl sulfoxide as the solvent. Effects of copolymerization systems on monomer apparent reactivity ratios for acrylonitrile/ammonium itaconate copolymers were studied. The values of monomer apparent reactivity ratios were calculated by Kelen‐Tudos method. The apparent reactivity ratios in the aqueous suspension polymerization system are similar to those in the solution polymerization system at polymerization conversions of less than 18% [reactivity ratio of acrylonitrile (r_AN) = 0.47 ± 0.01, reactivity ratio of ammonium itaconate (r_AIA) = 3.08 ± 0.01]. At conversions of more than 50%, the changes of monomer apparent reactivity ratios become less prominent (r_AN = 0.68 ± 0.01, r_AIA = 2.47 ± 0.01). In water‐rich reaction medium [(H₂O/dimethylsulfoxide (DMSO) > 80/20)], the monomer apparent reactivity ratios are approximately equivalent to those in the aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H₂O > 80/20), the apparent reactivity ratios are similar to those in the solution polymerization system. With an increase in the polarity of the solvent, the values of apparent reaction ratios both decrease. The values of apparent reaction ratios gradually tend to 1 with increasing the copolymerization temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3920–3923, 2007     

Batch and semicontinuous emulsion copolymerization of vinylidene chloride and butyl methacrylate. I. Kinetics in VDC–BMA emulsion polymerization and surface and colloidal properties of VDC–BMA latexes

Vinylidene chloride (VDC)—butyl methacrylate (BMA) comonomer mixtures with various composition (83 : 17, 60 : 40, 33 : 67 in mol %) were polymerized at 25°C using redox catalyst by batch and seeded semicontinuous emulsion copolymerization. The reactivity ratios determined in VDC (M₁)—BMA (M₂) emulsion copolymerization system were r₁ = 0.22 and r₂ = 2.41. Seven 35% solids (83 : 17 mol %) VDC–BMA copolymer latexes were prepared: one batch (G), one seeded batch (F), and 5 seeded semicontinuous polymerizations of 5 different monomer feed rates ranging from 0.27 (A) to 1.10 wt %/min (E). The kinetic studies of seeded semicontinuous polymerizations A-E showed that the rates of polymerizations (R_p) were controlled by the monomer addition rates (R_a). The conversion versus time curves for the polymerizations of 0 : 100–100 : 0 VDC–BMA mixtures by batch polymerization showed that the rate of polymerization (R_p) was a function of the number of particles, and that the rate of polymerization in a latex particle (R_pp) increased with increasing proportions of butyl methacrylate in the monomer mixture. All of the latexes had narrow particle size distributions. The greater particle number density in VDC polymerization and the greater water solubility of VDC suggest that the homogeneous nucleation mechanism is operative in VDC–BMA copolymerizations. The latex copolymers prepared by semicontinuous polymerization had lower number-and weight-average molecular weights than those of the corresponding batch copolymers, resulting from the monomer starvation occurring during the semicontinuous polymerization. The surface characterization study of the cleaned latexes showed that for the latexes by batch process, the surface charge density derived from strong-acid groups decreased with increasing proportion of VDC in the monomer mixture. On the other hand, for the latexes prepared by semicontinuous polymerization, the surface charge density derived from strong-acid groups did not depend on the monomer composition of the copolymers.     

Effect of medium pH on the reactivity ratios in acrylamide acrylic acid copolymerization

The copolymerization reactivity ratios of acrylic acid and acrylamide are found at pH 5 and pH 2. Automatic continuous online monitoring of polymerization reactions (ACOMP) has been used for the first time to monitor the synthesis of polyelectrolytic copolymers. The composition drift during the reactions revealed that at pH 5, the acrylamide participates more in the copolymer, and at pH 2, the acrylic acid incorporates in the system at a higher ratio. The copolymerization data were analyzed by a recent error in variables (EVM) type calculation method developed for obtaining the reactivity ratios by on‐line monitoring and gave at pH 5 reactivity ratios r_Aam = 1.88 ± 0.17, r_Aac = 0.80 ± 0.07 and at pH 2 r_Aam = 0.16 ± 0.04, r_Aac = 0.88 ± 0.08. The results show that the reactivity ratios depend strongly on the pH of the medium. The effect of polyelectrolytic interactions on the reactivity ratios is discussed in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 968–974, 2007     

Determination of reactivity ratios for the copolymerization of poly(acrylic acid‐co‐itaconic acid)

Monomer reactivity ratios are important parameters used in copolymerization kinetics to predict the rate of polymerization, copolymer composition and monomer sequence length, and by extension, molecular weight and distribution of the final product. Batch aqueous solution copolymerizations of acrylic acid (AA) and itaconic acid (IA) are performed at various feed compositions. Polymerizations are categorized into low (<11 wt %) conversion and higher (< 30 wt %) conversion data sets for analysis. Due to the limited solubility of IA in the reaction mixture, the feed composition of IA in all polymerizations is constrained to lower than 25 mol %. Conversion is determined by gravimetric methods, and copolymer composition via ¹H‐NMR spectroscopy. All data are analyzed using the error‐in‐variables model (EVM) method. Two analyses are used, one with the EVM approach and another with a novel Direct Numerical Integration (DNI) coupled with the EVM method. The DNI/EVM approach yields values of r_AA = 0.36 and r_IA = 1.62 for the reactivity ratios. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44014.     

Relative reactivities and graft distributions of polystyrene Macromers® in vinyl chloride copolymerization

Polystyrene macromonomers terminated with methacrylate, vinyl ether, or maleic half ester functionalities were evaluated in free radical initiated copolymerizations with vinyl chloride in aqueous suspension polymerization. Macromers® (M₁) terminated with methacrylate disappeared very rapidly in copolymerization with vinyl chloride (M₂). The relative reactivity ratio, r₂, was determined to be 0.05 in good agreement with literature values of about 0.04. Vinyl ether-terminated Macromers® had unexpectedly uniform reactivity with vinyl chloride in early conversion samples, but macromonomer conversion was incomplete. Macromers® having maleic half ester functionality were incorporated rapidly in vinyl chloride copolymerization at pH 2.5 (r₂ = 0.13). However, at pH 10 these Macromers® had reduced reactivity (r₂ = 0.34), which improved graft polymer uniformity. These Macromer® copolymerization relative reactivities are shown to be useful in predicting and controlling graft densities and graft polymer heterogeneity which influence morphology, processing, and mechanical properties.