Chain Transfer Constants Research Articles

Transformation from xanthate-type cationogen mediated metal-free RAFT cationic polymerization with “HCl·Et2O” into RAFT radical polymerization to form poly(alkyl vinyl ether)-b-polyvinyl alcohol amphiphiles

To elucidate the applicable range of metal-free RAFT cationic polymerization (MRCP) with “HCl·Et2O”, the effects of the monomer structure on the transformation from MRCP to RAFT radical polymerization were investigated. The MRCP with HCl·Et2O was conducted using the xanthate-type cationogen, O-ethyl S-(1-ethoxyethyl) carbonodithioate (EVEX) at 0 °C for alkyl vinyl ethers (ALVE) such as n-butyl (NBVE), isobutyl (IBVE), isopropyl (IPVE), and tert-butyl vinyl ethers (TBVE). It was demonstrated that EVEX acted efficiently as a RAFT cationogen for the cationic polymerization initiated by HCl·Et2O with good control over the molecular weight, polydispersity, and chain ends of the resulting poly(ALVE), regardless of the monomer structure of ALVE. The resulting chain-transfer constants indicate that EVEX is a substantially effective RAFT cationogen for MRCP of ALVE with HCl·Et2O. The resulting poly(ALVE) was utilized as a macromolecular chain transfer agent (macro-CTA) for RAFT radical polymerization since it had 0.72–0.76 of ω-end functionality for the xanthate group [–S–C(=S)OC2H5], as determined from 1H NMR and MALDI-TOF-MS spectra under the optimal conditions. However, when the resulting poly(TBVE) was employed for subsequent RAFT radical polymerization, no block copolymerization proceeded due to the poor stability of the vinyl ether radical. Thus, poly(ALVE) but not poly(TBVE) obtained by MRCP was available as a macro-CTA for RAFT radical polymerization to synthesize novel block copolymers such as poly(IPVE)-b-poly(vinyl acetate). In addition, the selectively saponified block copolymer, poly(IPVE)-b-polyvinyl alcohol, formed spherical micelles in water, demonstrating the successful results of the one-pot transformation from MRCP to RAFT radical polymerization.

The Chain Length Distribution of an Ideal Reversible Deactivation Radical Polymerization.

The chain length distribution (CLD) of a reversible deactivation radical polymerization at full conversion is shown to be a negative binomial distribution with parameters that are simple functions of the number-average degree of polymerization and either the chain transfer constant (in the case of polymerizations that incorporate a reversible chain transfer step) or the concentrations of dormant polymer chains and deactivating agent and the rate constants of propagation and deactivation (other types of RDRP). Expressions for the CLD at intermediate conversions are also derived, and shown to be consistent with known expressions for the number-average degree of polymerization and dispersity. It is further demonstrated that these CLDs are well-approximated by negative binomial distributions with appropriate choice of parameters. The negative binomial distribution is thus a useful model for CLDs of reversible deactivation radical polymerizations.

Radical Polymerization of Protonated Diallylammonium Monomers in Bidistilled Aqueous Solution: Kinetic Study

The kinetics of the radical polymerization of protonated monomers of the diallylammonium series (diallyl- and diallylmethylammonium trifluoroacetates) in bidistilled aqueous solution (quartz bidistiller) is studied in situ using 1Н NMR spectroscopy. The rates of monomer consumption and polymer accumulation in the range of 30–50°С are determined. For diallylammonium trifluoroacetate, the effective activation energy of polymerization and the constant of chain transfer to the monomer (30°С) are estimated. It is found that the initial rates of polymerization are comparable with the rates of polymerization of quaternized analogs and the constant of chain transfer to the monomer and the activation energy of polymerization are close to the analogous characteristics of polymerization in the case of quaternized diallyldimethylammonium chloride. It is shown that for polymerization in bidistilled solution, the constant of chain transfer to the monomer (30°С, 3.8 × 10–3) is more than three times lower than that for polymerization in monodistillate (30°С, 12.2 × 10–3) and the ММ of the polymers is ~2.4 times higher than the ММ of the samples synthesized in monodistillate under the same conditions. It is ascertained that standard electrolyte admixtures in distilled aqueous solution considerably affect radical chemical reactions involving protonated forms.

RAFT Polymerization of Tert-Butyldimethylsilyl Methacrylate: Kinetic Study and Determination of Rate Coefficients.

Well-defined poly(tert-butyldimethylsilyl methacrylate)s (TBDMSMA) were prepared by the reversible addition-fragmentation chain transfer (RAFT) process using cyanoisopropyl dithiobenzoate (CPDB) as chain-transfer agents (CTA). The experimentally obtained molecular weight distributions are narrow and shift linearly with monomer conversion. Propagation rate coefficients (kp) and termination rate coefficients (kt) for free radical polymerization of TBDMSMA have been determined for a range of temperature between 50 and 80 °C using the pulsed laser polymerization-size-exclusion chromatography (PLP-SEC) method and the kinetic method via steady-state rate measurement, respectively. The CPDB-mediated RAFT polymerization of TBDMSMA has been subjected to a combined experimental and PREDICI modeling study at 70 °C. The rate coefficient for the addition reaction to RAFT agent (kβ1, kβ2) and to polymeric RAFT agent (kβ) is estimated to be approximately 1.8 × 104 L·mol−1·s−1 and for the fragmentation reaction of intermediate RAFT radicals in the pre-equilibrium (k-β1, k-β2) and main equilibrium (k-β) is close to 2.0 × 10−2 s−1. The transfer rate coefficient (ktr) to cyanoisopropyl dithiobenzoate is found to be close to 9.0 × 103 L·mol−1·s−1 and the chain-transfer constant (Ctr) for CPDB-mediated RAFT polymerization of TBDMSMA is about 9.3.

Free Radical Polymerization Behavior of the Vinyl Monomers from Plant Oil Triglycerides

A one-step method of plant oil direct transesterification was used to synthesize new vinyl monomers from sunflower (SFM), linseed (LSM), soybean (SBM), and olive (OVM) oils. The degree of unsaturation in plant oil fatty acids was used as a criterion to compare the free radical polymerization behavior of new monomers. The number-average molecular weight of plant oil-based homopolymers synthesized in toluene in the presence of AIBN at 75 °C varies at 11 000–25 000 and decreases as follows: poly(OVM) > poly(SFM) > poly(SBM) > poly(LSM), corresponding to increasing degree of unsaturation in the monomers. Rate of polymerization depends noticeably on the degree of unsaturation in monomers. Due to the allylic termination, chain propagation coexists with effective chain transfer during polymerization. The obtained values of CM (ratio of chain transfer and propagation rate constants) depends on monomer structure as follows: CM(LSM) > CM(SBM) > CM(SFM) > CM(OVM). 1H NMR spectroscopy shows that the fraction of the r...

Polymerization of mono‐, Di‐, and trichloroethyl methacrylates: A study in chain transfer

ABSTRACTBulk free radical polymerization of the monomer series CH2 = C(CH3)C(O)OCH2CH3‐nCln, n = 1, 2, 3, yields an unexpectedly crosslinked product with a crosslink density that increases with decreasing chlorine content of the respective monomer (n = 3 < n = 2 < n = 1). This chlorine substituent effect is investigated by correlation with chain transfer constant measurements for four homologous series of chloroalkyl compounds (chloroethyl acetates (CH3C(O)OCH2CH3‐nCln, n = 1,2,3); chloromethanes (CH4‐nCln, n = 2,3,4) and CD2Cl2 and CDCl3 analogs; butyl chloride isomers (n‐, iso‐, sec‐, tert‐) and tert‐C4D9Cl analog; and nine chloroethanes (C2Hn−6Cln, n = 1–6)) in a methyl methacrylate polymerization. The pattern conveyed by the magnitude of chain transfer constants and deuterium isotope effects is consistent with a vicinal chlorine effect (i.e., chlorine activation of a vicinal hydrogen for abstraction) to account for the relative activities of the four series of model compounds and for the propensity of the chloroethyl methacrylates to crosslink in a bulk free radical polymerization. The chloroalkyl moiety's contribution to chain transfer is relatively modest (≤10−4), but, when incorporated as a monomer pendant group in free radical polymerizations, it is effective in broadening molecular weight to the extent of resulting in a crosslinked polymer. Published 2016.† J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 93–106

A high molecular weight acrylonitrile copolymer prepared by mixed solvents polymerization: II. effect of DMSO/water ratios on polymerization and stabilization

A bifunctional comonomer β-methylhydrogen itaconate was synthesized to prepare high molecular weight poly [acrylonitrile-co-(β-methylhydrogen itaconate)] [P (AN-co-MHI)] by mixed solvents polymerization, which was used as carbon fiber precursor instead of acrylonitrile terpolymers. The effect of dimethyl sulfoxide (DMSO)/deionized water ratios on the polymerization, structure and stabilization of P (AN-co-MHI) was studied by elemental analysis, UV-Visible Spectroscopy, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The highest viscosity-average molecular weight (76.72 × 104 g/mol) of P(AN-co-MHI) was obtained in the mixed solvents of DMSO/deionized water = 10/90 (wt/wt) due to the zero chain transfer constant of deionized water for radical ~ ~ ~AN·, which is 10 times larger than that of P(AN-co-MHI) copolymers prepared in DMSO solution polymerization under the same conditions and is beneficial to improving the tensile strength of resulting carbon fiber. The composition of P(AN-co-MHI) was controlled by the ratio of DMSO/deionized water in the mixed solvents, it is attributed to the changes of AN/MHI ratio taking part in the polymerization reactions, which is caused by the different solubility of AN in the mixed solvents. From elemental analysis and FTIR studies, it can be found out that the content of MHI in P(AN-co-MHI) copolymer becomes larger with the increase of DMSO content in the mixed solvents. The FTIR, XRD and DSC results show that the stabilization of P(AN-co-MHI) copolymer was significantly improved by MHI compared with PAN homopolymer and poly (acrlonitrile-methyl acrylate-acrylic acid) terpolymer, such as larger extent of stabilization, lower initiation temperature and smaller Ea of cyclization, which is beneficial to preparing high performance carbon fiber.

Thiol–ene grafting from polylactic acid, polycaprolactone, and polyhydroxybutyrate

Thiol–ene additions of different monomers from multi-thiol functionalized biodegradable polymers are analyzed in this study. These monomers include quaternary ammonium groups known for their biological activities; and also methyl methacrylate (MMA) and hydroxyethyl methacrylate (HEMA), which are used to control the hydrophilic–hydrophobic balance in the issued copolymers. Monomer conversion and the resulting polymer structures are confirmed principally by 1H nuclear magnetic resonance (NMR) spectra. Model reactions are first conducted with thiophenol, and then polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxybutyrate (PHB) multi-thiol functionalized polymers are successfully used. The structures of the obtained products are analyzed by 1H NMR spectra: all the reactions are kinetically controlled and monomer additions are controllable. Chain transfer constants of the used monomers to the multi-thiol functionalized PLA are between 1.4 and 1.9. The obtained products were also characterized by size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA).

One-step synthesis of poly(lactic-co-glycolic acid)-g-poly-1-vinylpyrrolidin-2-one copolymers

The radical polymerization of 1-vinylpyrrolidin-2-one (NVP) in poly(lactic-co-glycolic acid) (PLGA) 50:50 at 100 °C leads to amphiphilic PLGA-g-PVP copolymers. Their composition is determined by FT-IR spectroscopy. Thermogravimetric analyses agree with FT-IR determinations. Saponification of the PLGA-g-PVP polyester portion allows isolating the PVP side chains and measuring their molecular weight, from which the average chain transfer constant (CT) of the PLGA units is estimated. The MALDI-TOF spectra of PVP reveal the presence at one chain end of residues of either glycolic acid- or lactic acid- or lactic/glycolic acid dimers, trimers and one tetramer, the other terminal being hydrogen. This unequivocally demonstrates that grafting occurred. Accordingly, the orthogonal solvent pair ethyl acetate—methanol, while separating the components of PLGA/PVP intimate mixtures, fails to separate pure PVP or PLGA from the reaction products. All PLGA-g-PVP and PLGA/PLGA-g-PVP blends, but not PLGA/PVP blends, give long-time stable dispersions in water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1919–1928

The potential of 1H NMR spectroscopy for studying the kinetics and mechanism of controlled radical polymerization with reversible chain transfer

The potential of 1H NMR spectroscopy for determining the constants of chain transfer to a symmetric bifunctional agent of reversible chain transfer and for studying the changes in the current concentrations of the initial and final agents formed during the replacement of one leaving group with a polymer (oligomeric) radical of the agents of reversible chain transfer during the homopolymerization of N-vinyl succinimide, the homopolymerization of vinyl acetate, and the copolymerization of 4-vinylpyridine and tert-butyl acrylate in the presence S,S-dibenzyltrithiocarbonate is studied. The correct calculation of the constants of chain transfer is shown to be possible only during agreement of the studied system with the taken scheme of polymerization with reversible chain transfer, a minimum contribution of side reactions, and signal separation that is sufficient for the quantitative analysis of initial and polymer (monosubstituted) agents of reversible chain transfer in the 1H NMR spectra. The lower limit of the constants of transfer to the polymer agents of reversible chain transfer is estimated, and the great efficiency of these agents in comparison to that of the initial low-molecular-mass ones is directly confirmed. A complex of necessary investigations to study any new polymerization system where the controlled radical homoand copolymerization with reversible chain transfer in the presence of symmetric trithiocarbonates occurs is performed.

Methyl methacrylate polymerization involving a cobalt ortho-iminobenzosemiquinone complex: Determination of the chain transfer constant

We studied the effect of bis[4,6-di-tert-butyl-N-(2,6-dimethylphenyl)-ortho-iminobenzosemi-quinono]cobalt(II) on the kinetics of the bulk polymerization of methyl methacrylate at 70°C and on the molecular-weight characteristics of the polymer synthesized. The effective chain transfer constant in the polymerization of methyl methacrylate in the presence of the complex in benzene at 70°C was determined by the Mayo method and by linearizing the macromolecule chain length distribution. The constants obtained were compared with the same parameters available from the literature for a number of known chain-transfer agents, viz., dodecyl mercaptan and cobalt porphyrin and oxime complexes.

Well-Defined High Molecular Weight Polystyrene with High Rates and High Livingness Synthesized via Two-Stage RAFT Emulsion Polymerization.

A highly living polymer with over 100 kg mol(-1) molecular weight is very difficult to achieve by controlled radical polymerization since the unavoidable side reactions of irreversible radical termination and radical chain transfer to monomer reaction become significant. It is reported that over 500 kg mol(-1) polystyrene with high livingness and low dispersity could be synthesized by a facile two-stage reversible addition-fragmentation transfer emulsion polymerization. The monomer conversion reaches 90% within 10 h. High livingness of the product is ascribed to the extremely low initiator concentration and the chain transfer constant for monomer unexpectedly much lower than the well-accepted values in the conventional radical polymerization. The two-stage monomer feeding policy much decreases the dispersity of the product.

Mangiferin as chain transfer agent: effect on the molecular weight of poly(methyl methacrylate) and polystyrene

Free radical polymerization of methyl methacrylate (MMA) and styrene (St) has been performed in N,N-dimethylformamide (DMF) at 70 °C in the presence of varying concentration of mangiferin as chain transfer agent using 2,2′-azobisisobutyronitrile (AIBN) as initiator. With increase in mangiferin concentration, molecular weight of the obtained polySt gradually decreases as expected due to the chain transfer phenomenon, but that of polyMMA interestingly increases possibly due to the preferential auto-acceleration phenomenon during MMA polymerization in the presence of higher concentration of mangiferin. The observed chain transfer constant of mangiferin for styrene polymerization is 0.14. The incorporation of mangiferin in the resultant polymers is confirmed by FTIR and UV–Vis studies.

Facile Synthesis of Well-Defined MDMO-PPV Containing (Tri)Block—Copolymers via Controlled Radical Polymerization and CuAAC Conjugation

A systematic investigation into the chain transfer polymerization of the so-called radical precursor polymerization of poly(p-phenylene vinylene) (PPV) materials is presented. Polymerizations are characterized by systematic variation of chain transfer agent (CTA) concentration and reaction temperature. For the chain transfer constant, a negative activation energy of −12.8 kJ·mol−1 was deduced. Good control over molecular weight is achieved for both the sulfinyl and the dithiocarbamate route (DTC). PPVs with molecular weights ranging from thousands to ten thousands g·mol−1 were obtained. To allow for a meaningful analysis of the CTA influence, Mark–Houwink–Kuhn–Sakurada (MHKS) parameters were determined for conjugated MDMO-PPV ([2-methoxy-5-(3',7'-dimethyloctyloxy)]-1,4-phenylenevinylene) to α = 0.809 and k = 0.00002 mL·g−1. Further, high-endgroup fidelity of the CBr4-derived PPVs was proven via chain extension experiments. MDMO-PPV-Br was successfully used as macroinitiator in atom transfer radical polymerization (ATRP) with acrylates and styrene. A more polar PPV counterpart was chain extended by an acrylate in single-electron transfer living radical polymerization (SET-LRP). In a last step, copper-catalyzed azide alkyne cycloaddition (CuAAC) was used to synthesize block copolymer structures. Direct azidation followed by macromolecular conjugation showed only partial success, while the successive chain extension via ATRP followed by CuAAC afforded triblock copolymers of the poly(p-phenylene vinylene)-block-poly(tert-butyl acrylate)-block-poly(ethylene glycol) (PPV-b-PtBuA-b-PEG).

Kinetics study of living microemulsion polymerization mediated by reversible addition-fragmentation chain transfer

Reversible addition-fragmentation chain transfer (RAFT) polymerization is usually carried out in emulsion or miniemulsion, often encounters problems of rate retardation, phase separation, and loss of activity in these systems. Compared with emulsion or miniemulsion, microemulsion remains stable during polymerization because of presence of large amount surfactant that promotes formation of large number of monomer swollen micelles. Therefore, microemulsion typically shows fast polymerization rate and produces latex nanoparticles composed of high molecular weights polymers. Until now, only few RAFT polymerizations have been successfully conducted in microemulsion and related kinetics studies are very limited. Here, kinetics studies on RAFT microemulsion polymerization were carried out and the factors that affected kinetics were detailedly investigated. Kinetic parameters, theoretical molecular weights, chain transfer constant, propagate rate constant, half reaction time and polymerization rate constant were all calculated. Experimental results indicated temperature and concentration of chain transfer agent were important factors which influenced polymerization kinetics. In addition, the chemical structure of chain transfer agent, molecular weights and its distribution, and the morphologies structure of polymers were characterized by 1H NMR, FT-IR, GPC and TEM, respectively.

Theoretical study of chain transfer to solvent reactions of alkyl acrylates.

This computational and theoretical study deals with chain transfer to solvent (CTS) reactions of methyl acrylate (MA), ethyl acrylate (EA), and n-butyl acrylate (n-BA) self-initiated homopolymerization in solvents such as butanol (polar, protic), methyl ethyl ketone (MEK) (polar, aprotic), and p-xylene (nonpolar). The results indicate that abstraction of a hydrogen atom from the methylene group next to the oxygen atom in n-butanol, from the methylene group in MEK, and from a methyl group in p-xylene by a live polymer chain are the most likely mechanisms of CTS reactions in MA, EA, and n-BA. Energy barriers and molecular geometries of reactants, products, and transition states are predicted. The sensitivity of the predictions to three hybrid functionals (B3LYP, X3LYP, and M06-2X) and three different basis sets (6-31G(d,p), 6-311G(d), and 6-311G(d,p)) is investigated. Among n-butanol, sec-butanol, and tert-butanol, tert-butanol has the highest CTS energy barrier and the lowest rate constant. Although the application of the conductor-like screening model (COSMO) does not affect the predicted CTS kinetic parameter values, the application of the polarizable continuum model (PCM) results in higher CTS energy barriers. This increase in the predicted CTS energy barriers is larger for butanol and MEK than for p-xylene. The higher rate constants of chain transfer to n-butanol reactions compared to those of chain transfer to MEK and p-xylene reactions suggest the higher CTS reactivity of n-butanol.

Kinetic Features of Hexene-1 Polymerization over Supported Titanium-Magnesium Catalyst

The data on the effect of cocatalyst composition and polymerization conditions on activity and MWD of polyhexene (PH) produced over a high-activity titanium-magnesium catalyst are obtained. The cocatalyst has an extremely strong effect on the MWD of polyhexene. When triisobutylaluminum is used as a cocatalyst, PH with high Mw and narrow MWD is produced. The use of TEA decreases the Mw of PH and broadens the MWD. It is found the ratio between the rate constant of chain transfer to TEA (ktrAl) and the propagation rate constant (kp) is two orders of magnitude higher than the ktrAl/kp value calculated for polymerization of ethylene and propylene. We attributed this effect to formation of polyhexene in the solution, as opposed to polymerization of ethylene and propylene in slurry polymerization. The addition of hydrogen at polymerization of hexene-1 significantly increases activity and stereospecificity.

Kinetic regularities of catalytic ethylene polymerization on single- and multi-site cobalt and vanadium bis(imino)pyridine complexes

The number of active centers Cp in the homogeneous complexes LCoCl2 and LVCl3 (L = 2,6-(2,6-R2C6H3N=CMe)2C5H3N; R = Me, Et, tBu) and the propagation rate constants kp have been determined by the radioactive 14CO quenching of ethylene polymerization on these complexes in the presence of the methylaluminoxane (MAO) activator. For the systems studied, a significant portion of the initial complex (up to 70%) transforms into polymerization-active centers. The catalysts based on the cobalt complexes are single-site, and the constant kp in these systems is independent of the volume of substituent R in the ligand, being (2.4−3.5) × 103 L mol−1 s−1 at 35°C. The much larger molecular weight of the polymer formed on the complex with the tert-butyl substituent in the aryl rings of the ligand compared to the product formed on the complex with the methyl substituent is due to the substantial (∼11-fold) decrease in the rate constant of chain transfer to the monomer. At the early stages of the reaction (before 5 min), the vanadium complexes contain active centers of one type only, for which kp = 2.6 × 103 L mol−1 s−1 at 35°C. An increase in the polymerization time to 20 min results in the appearance, in the vanadium systems, of new, substantially less reactive centers on which high-molecular-weight polyethylene forms. The number of active centers Cp in the 2,5-tBu2LCoCl2 and 2,6-Et2LVCl3 systems with the MAO activator increases as the polymerization temperature is raised from 25 to 60°C. The activation energies of the chain propagation reaction (Ep) have been calculated. The value of Ep for complex 2,5-tBu2LCoCl2 is 4.5 kcal/mol. It is assumed that the so-called “dormant” centers form in ethylene polymerization on the 2,6-Et2LVCl3 complex, and their proportion increases with a decrease in the polymerization temperature. Probably, the anomalously high value Ep = 14.2 kcal/mol for the vanadium system is explained by the formation of these “dormant” centers.

Branching generation during the free radical copolymerization of p-vinyl benzene sulfonyl chloride with styrene

The branching generation during the free radical copolymerization of chain transfer monomer p-vinyl benzene sulfonyl chloride (VBSC) with styrene was investigated by a simple mathematic model. Chain transfer constant of VBSC was determined to be around 0.3 by fitting the 1H-NMR monitored experimental results with a mathematic model. According to the theoretical analysis, the obtained poly(VBSC) and its copolymers were substantiated to have a grafting-like main chain with residual pendent sulfonyl chloride groups after consuming most of the vinyl groups. The copolymerization results of VBSC with styrene at varied feed ratios demonstrated that conversion of sulfonyl chloride groups was lower than that of the monomer, which was in agreement with the theoretical results. The glass transition temperature, number average molecular weight and distribution of those obtained polymers were primarily investigated. Comparing with other chain transfer monomers, VBSC has a chain transfer constant much closer to unity therefore a more branched polymer is expected. Additionally, the branched polystyrene with residual sulfonyl chloride groups is hopefully to be further used as ATRP macroinitiators or reactive intermediates to synthesize functional polymers with complex structure.

RAFT Polymerization of Monomers with Highly Disparate Reactivities: Use of a Single RAFT Agent and the Synthesis of Poly(styrene-block-vinyl acetate)

A single reversible addition–fragmentation chain transfer (RAFT) agent, malonate N,N-diphenyldithiocarbamate (MDP-DTC) is shown to successfully mediate the polymerization of several monomers with greatly differing reactivities in radical/RAFT polymerizations, including both vinyl acetate and styrene. The chain transfer constants (Ctr) for MDP-DTC for both these monomers were evaluated; these were found to be ~2.7 in styrene and ~26 in vinyl acetate, indicating moderate control over styrene polymerization and good control of vinyl acetate polymerization. In particular, the MDP-DTC RAFT agent allowed for the synthesis of block copolymers of these two monomers without the need for protonation/deprotonation switching, as has been previously developed with N-(4-pyridinyl)-N-methyldithiocarbamate RAFT agents, or other end-group transformations. The thermal properties of the block copolymers were studied using differential scanning calorimetry, and those with sufficiently high molecular weight and styrene composition appear to undergo phase separation. Thus, MDP-DTC may be useful for the production of other block copolymers consisting of monomers with highly dissimilar reactivities.