Micellar RAFT/MADIX Polymerization

Transcription

1 Micellar RAFT/MADIX Polymerization Cécile Barthet,, James Wilson l, Arnaud Cadix l, Mathias Destarac, Christophe Chassenieux*,, Simon Harrisson*, Laboratoire des IMRCP, Université de Toulouse, CNRS UMR 5623, Université Paul Sabatier, 118 route de Narbonne Toulouse Cedex 9, France l Solvay Novecare, Research and Innovation Centre Paris, Aubervilliers, France Le Mans Université, Institut des Molécules et Matériaux du Mans (IMMM) UMR 6283, Avenue Olivier Messiaen Le Mans Cedex 9, France 1. Materials and Methods The redox couple composed of ammonium persulfate (APS, purity 98%) and sodium formaldehyde sulfoxylate (NaFS, purity 98%) was used as initiators and were purchased from Sigma-Aldrich. Acrylamide (Am, solution at 50% in water) and 2-Acrylamido-2-methyl-1-propanesulfonic acid sodium salt solution (AMPS, solution at 50% in water) were kindly donated by Solvay. The hydrophobic monomer 4-tert butyl styrene (tbs, purity 99%) was also purchased from Sigma Aldrich. HPLC solvent was purchased from VWR (methanol as HPLC grade) and NMR solvent from Euriso-top (deuterium oxide, D 2 O for 1 H NMR). Sodium nitrate (NaNO 3, purity 99%) and sodium azide (NaN 3, purity 99%) were purchased from Sigma-Aldrich and used to prepare the eluent for Size Exclusion Chromatography (SEC). Sodium dodecyl sulfate (SDS, Rhodapon LS 94 RPB grade, 95%), Rhodixan A1 RAFT/MADIX agent (CTA) were also kindly given by Solvay. Deionized water was used in all experiments. The PAm 7 -XA1 macro-raft agent 1 was prepared using the procedure described in Read et al. paper. 2,2'-Azobis[2-methylpropionamidine], dihydrochloride (V50, purity 97%) was purchased from Wako and was used as initiator to synthesize PAm 7 -XA1 macro-cta Synthesis of PAm 7 -XA1 macro-raft agent The macro chain transfer agent (macro-cta) was prepared according to the method described by Read et al. 1. The chain transfer agent Rhodixan A1 (5.92 g, 28.35mmol) was dissolved in g of ethanol in a one-neck round-bottom flask. Then, acrylamide (28.35 g, mmol), V50 (243 mg, 0.90mmol) and distilled water (12.72 g) were added. The mixture was degassed by bubbling argon for 30 min while stirring. Then it was heated under argon atmosphere at 60 C for 3h until the completion of the reaction. The ethanol was evaporated under vacuum prior to freeze-drying the sample to give a light yellow powder. After freeze-drying, the yield was estimated by 1 H NMR to be of 100%. The calculated molar mass by 1 H NMR is 477 g/mol. The molar mass of the polymers have been compared to the theoretical number average molecular weight (Mn th ) that would be obtained in the case of a perfectly controlled polymerization. The theoretical number average molecular weight is calculated using equation (1.1): 1

2 where Mn th [M] 0 [X] 0 M MU Mn = M M X Conv.+M (1.1) Theoretical number average molecular weight Initial concentration of monomer Initial concentration of chain transfer agent Molar mass of the monomer Conv. Conversion of the monomer (yield of the reaction) M X Molar mass of the chain transfer agent 1.2. Synthesis of hydrophilic polymers via RAFT/MADIX polymerization Study of the kinetics The kinetics of the reactions has been systematically studied according to the following procedure. A stock solution containing all reagents except the initiators was first prepared and put under agitation until a transparent solution was obtained. Its ph was adjusted to 6using a solution of H 2 SO 4 at 1wt%. This stock solution was divided into three different batches (one-neck round-bottom flasks of ml) called batches A, B and C. The reaction mixtures were then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. NaFS and APS redox initiators were then injected to start the polymerization, as well as the kinetics study. The three reactions were run in parallel and staggered samples were taken so that the reproducibility of the reaction could be examined. A typical sampling was handled as depicted in table S1. Table S1 Typical sampling times made during the kinetics Batch A (time in min) Batch B (time in min) Batch C (time in min) Samples of 0.2 ml are taken from the batches at designated times (see table S1). From these samples, 0.1 g was diluted with 1 g D 2 O in order to carry out 1 H NMR analysis g was diluted in 2 g of the SEC-MALS eluent (NaNO 3 at 0.1 M and NaN 3 at 100 ppm in solution in water) and analyzed in aqueous SEC-MALS. Another 0.04 g of reactive medium are weighed and diluted in 2 g of methanol to be afterwards analyzed in HPLC and hence determine the conversion of tbs with time. 2

3 Redox initiated RAFT/MADIX micellar polymerization of P(Am 80 -co-amps 20 ) 100k A typical redox-initiated RAFT/MADIX polymerization of P(Am 80 -co-amps 20 ) was carried out as follows: g of PAm 7 -XA1 at 81wt%, deionized water (36.5 g), Am (7.25 g, as a 50wt% aqueous solution) and 6.65 g AMPS in solution at 50wt% in water were mixed together. The ph of the mixture was adjusted to 6 by adding a 1wt% solution of H 2 SO 4.The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. NaFS (7.95 mg, as a 0.5wt% aqueous solution) was injected, followed by APS (79.5 mg, as a 5wt% aqueous solution). The injection of APS marked the start of the reaction and time zero of the kinetic study. The reaction was maintained at 25 C under a stream of argon for 2 hours until completion of the reaction (conversion of hydrophilic monomers = 99.6%, Mn SEC-MALS = g/mol, Đ = 1.10, dn/dc = ml/g) Redox initiated RAFT/MADIX micellar polymerization of P(Am 80 -co-amps 20 ) 100k in presence of SDS A typical redox-initiated RAFT/MADIX polymerization of P(Am 80 -co-amps 20 ) in presence of SDS was carried out as follows: g of PAm 7 -XA1 at 86.3wt%, SDS (0.86 g, 2.97 mmol) pre-solubilized in deionized water (7.44 g), Am in solution at 50wt% in water (6.64 g, 46.7 mmol) and AMPS in solution at 50wt% in water (5.36 g, 11.7 mmol) were mixed together. The ph of the mixture was adjusted to 6 by adding a 1 wt% solution of H 2 SO 4. The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. NaFS (4.82 mg, as a 0.1wt% aqueous solution) was injected, followed by APS (24.25 mg, as a 0.5wt% aqueous solution). The injection of APS marked the start of the reaction and time zero of the kinetic study. The reaction was left at 25 C under a stream of argon for 2 hours until completion of the reaction (global conversion = 98.4%, Mn SEC-MALS = g/mol, Đ = 1.13, dn/dc = ml/g) Synthesis of associative polymers via RAFT/MADIX micellar polymerization All associative polymers used in this work were synthesized according to the micellar copolymerization method described by Candau and co-workers 2 4. In this process, the hydrophobic monomers are solubilized within surfactant micelles, while hydrophilic monomers are located in the aqueous medium. This micro-heterogeneity leads to copolymers with a largely block-like distribution of the hydrophobic units along the backbone. The length of the hydrophobic segment is assumed to be equal to the number of hydrophobic monomers per micelle Preparation of the micellar solution containing the hydrophobic monomer A micellar solution containing tbs (1.73 g, mmol) and SDS (16.01 g, mmol) dissolved in deionized water (62.40 g) was always prepared before adding the other reagents of the RAFT/MADIX micellar polymerization. The amount of tbs was determined to give a targeted concentration of hydrophobes (C H ) of 1 mol%. The tbs/sds concentration ratio was fixed at 0.11 wt%. If we assume that Nagg of SDS (62 in pure water) is unaffected by the presence of Am and AMPS, then the average number of tbs molecules per 3

4 micelle (N H ) is 12. This figure is given to facilitate comparison with other studies, but is not an experimentally determined parameter. Determination of the real N H would require a light scattering study that is beyond the scope of this article Redox initiated RAFT/MADIX micellar polymerization P(Am 80 -co-amps 20 -cotbs 1mol% ) 100k A redox initiated RAFT/MADIX micellar polymerization of P(Am-co-AMPS-co-tBS) was performed as follows: a micellar solution containing tbs (1.73 g, mmol) and SDS (16.01 g, mmol) dissolved in deionized water (62.40 g) was first prepared. PAm 7 -XA1 (0.034 g, mmol), 4.26 g of the micellar solution, Am (6.52 g, mmol), AMPS (5.26 g, mmol) and 4.41 g of deionized water were added to a one-neck round-bottomed flask containing a magnetic bar. The ph of the mixture was adjusted to 6 in the mean of a solution of H 2 SO 4 at 1wt%. The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. Once the bubbling is over, 4.75gof NaFS at 0.1wt% in water was first injected g of APS at 0.5wt% in water were afterwards injected and the reaction could start, as well as the kinetic study. The reaction was left at 25 C under a stream of argon for 24 hours until completion of the reaction (global conversion = 98.4%, tbs conversion = 96.8%, Mn SEC-MALS = g/mol, Đ = 1.38, dn/dc = ml/g) Chain extension of associative polymers with acrylamide Once again, the amount of tbs has been determined knowing that the number of hydrophobes per micelle (N H ) was fixed at 12 and the targeted concentration of hydrophobes (C H ) is 1 mol%. The aggregation number of SDS (Nagg) was taken equal to Synthesis of P(Am 80 -co-amps 20 -co-tbs 1mol% ) 10k prepolymer A redox initiated RAFT/MADIX micellar polymerization of P(Am 80 -co-amps 20 -co-tbs 1mol% ) was performed out as follows: a micellar solution containing tbs (1.73 g, mmol) and SDS (16.01 g, mmol) dissolved in deionized water (62.40 g) was first prepared. 7.6 g of acrylamide (in solution at 50% in water and copper-free), 6.2 g of an aqueous solution of AMPS (at 50% in water), 5.0 g of the micellar solution, 0.4 g of PAm 7 -XA1 at 86.3% and 4.6 g of deionized water were added to a one-neck round-bottom 60 ml flask containing a magnetic bar. The ph of the mixture was adjusted to 6 in the mean of a solution of H 2 SO 4 at 1wt%. The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. Once the bubbling is over, 5.6 g of NaFS at 0.1wt% in water was first injected. 5.6 g of APS at 0.5wt% in water were afterwards injected and the reaction could start, as well as the kinetic study. The reaction was let at 25 C under a stream of argon for 24 hours until completion of the reaction (conversion of hydrophilic monomers = 98.5%, tbs conversion = 100%, Mn SEC-MALS = g/mol, Đ = 1.08, dn/dc = ml/g). P(Am 80 -co-amps 20 -co-tbs 1mol% ) 10k copolymer is used directly as prepolymer for extension with acrylamide without purification or drying. 4

5 Chain extension of P(Am 80 -co-amps 20 -co-tbs 1mol% ) 10k to P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k -b-pam, Mn th = g/mol A redox initiated RAFT/MADIX polymerization of PAm was performed considering P(Am 80 -co-amps 20 - co-tbs 1mol% ) 10k as chain transfer agent. 8 g of acrylamide (in solution at 50% in water and copper-free), 3.2 g of P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k prepolymer (at 20wt% in solution in water, non-purified) and 5.5 g of deionized water were added to a one-neck round-bottom 60 ml flask containing a magnetic bar. The ph of the mixture was adjusted to 6 in the mean of a solution of H 2 SO 4 at 1wt%. The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. Once the bubbling is over, 1.6 g of NaFS at 0.1wt% in water was first injected. 1.6 g of APS at 0.5wt% in water were afterwards injected and the reaction could start, as well as the kinetic study. The reaction was let at 25 C under a stream of argon for 24 hours until completion of the reaction (Am conversion = 99.6%, Mn SEC-MALS = g/mol, Đ = 1.07, dn/dc = ml/g) Chain extension of P(Am 80 -co-amps 20 -co-tbs 1mol% ) 10k to P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k -b-pam, Mn th = g/mol A redox initiated RAFT/MADIX polymerization of PAm was performed considering P(Am 80 -co-amps 20 - co-tbs 1mol% ) 10k as chain transfer agent. 8 g of acrylamide (in solution at 50% in water and copper-free), 1.6 g of P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k prepolymer (at 20wt% in solution in water, used non-purified) and 7.3 g of deionized water were added to a one-neck round-bottom 60 ml flask containing a magnetic bar. The ph of the mixture was adjusted to 6 in the mean of a solution of H 2 SO 4 at 1wt%. The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. Once the bubbling is over, 1.6 g of NaFS at 0.1wt% in water was first injected. 1.6 g of APS at 0.5wt% in water were afterwards injected and the reaction could start, as well as the kinetic study. The reaction was let at 25 C under a stream of argon for 24 hours until completion of the reaction (Am conversion = 99.7%, Mn SEC-MALS = g/mol, Đ = 1.10, dn/dc = ml/g) Chain extension of P(Am 80 -co-amps 20 -co-tbs 1mol% ) 10k to P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k -b-pam, Mn th = g/mol A redox initiated RAFT/MADIX polymerization of PAm was performed considering P(Am 80 -co-amps 20 - co-tbs 1mol% ) 10k as chain transfer agent. 8 g of acrylamide (in solution at 50% in water and copper-free), 0.31 g of P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k prepolymer (at 20wt% in solution in water, used non-purified) and 8.6 g of deionized water were added to a one-neck round-bottom 60 ml flask containing a magnetic bar. The ph of the mixture was adjusted to 6 in the mean of a solution of H 2 SO 4 at 1wt%. The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. Once the bubbling is over, 1.6 g of NaFS at 0.1wt% in water was first injected. 1.6 g of APS at 0.5wt% in water were afterwards injected 5

6 and the reaction could start, as well as the kinetic study. The reaction was let at 25 C under a stream of argon for 24 hours until completion of the reaction (Am conversion = 98.6%, Mn SEC-MALS = g/mol, Đ = 1.13, dn/dc = ml/g) Chain extension of P(Am 80 -co-amps 20 -co-tbs 1mol% ) 10k to P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k -b-pam, Mn th = g/mol A redox initiated RAFT/MADIX polymerization of PAm was performed considering P(Am 80 -co-amps 20 - co-tbs 1mol% ) 10k as chain transfer agent. 8 g of acrylamide (in solution at 50% in water and copper-free), 0.17 g of P(Am 80 -co-amps 20 -cotbs 1mol% ) 10k prepolymer (at 20wt% in solution in water, non-purified) and 8.8 g of deionized water were added to a one-neck round-bottom 60 ml flask containing a magnetic bar. The ph of the mixture was adjusted to 6 in the mean of a solution of H 2 SO 4 at 1wt%. The reactive medium was then placed in a thermostated bath set at 25 C while bubbling argon for 45 minutes. Once the bubbling is over, 1.6 g of NaFS at 0.1wt% in water was first injected. 1.6 g of APS at 0.5wt% in water were afterwards injected and the reaction could start, as well as the kinetic study. The reaction was let at 25 C under a stream of argon for 24 hours until completion of the reaction (Am conversion = 95%, Mn SEC-MALS = g/mol, Đ = 1.13, dn/dc = ml/g). The polymers were all at 20% solids in water. Molecular mass values have been determined by aqueous SEC-MALS Size exclusion chromatography (SEC-MALS) The molecular weight distribution of the synthesized copolymers and associative polymers were determined by aqueous SEC-MALS (eluent: solution of NaNO 3 at 0.1 M and NaN 3 at 100 ppm in water). SEC-MALS analyses were carried out on an Agilent 1100 HLPC system including a vacuum degasser and an isocratic pump monitored by an Eclipse 2 system (Wyatt technology), a guard column ShodexSB807-G and two columns ShodexOHpak in series (two SB806M HQ (8mm*300mm, 13µm)) coupled with a refractometer (OptilabRex, Wyatt technology), a UV detector (Agilent) set at 290 nm and a multi-angle laser light scattering detector (Dawn HeleosII + QELS, 18 angles, Wyatt technology). The flow rate was 1 ml/min. Prior to injections, samples were filtered through 0.45µm PTFE filters. The refractive index increment dn/dc of each sample to its composition in AMPS was calculated with equation (1.2) where W Am and W AMPS are the mass fractions of the two monomers in the copolymer and with dn/dc Am =0.183 ml/g and dn/dc AMPS =0.113 ml/g in the corresponding eluent at T=25 C. 1 dn dc =W dn / dc +W dn dc (1.2) was taken equal to ml/g in the case of Am/AMPS ratio of 80:20, for both hydrophilic / and associative copolymers. The contribution of tbs to 6 / is neglected because its content in

7 the reactive medium is negligible compared to that of acrylamide and AMPS (Am:AMPS:tBS weight ratio is 54.5:44:1.5). Equation (1.2) has also been used to determine dn/dc of the chain extended polymers, with increasing contribution of PAm block H NMR spectroscopy All 1 H NMR spectra were recorded on a Bruker AMX 300 at 300MHz in D 2 O High pressure liquid chromatography (HPLC) The conversion of tbs during the polymerizations was determined using HPLC in methanol. The HPLC setup comprised one ZORBAX Eclipse XDB-C8 column (4.6 x 150 mm, 5µm) purchased from Agilent in series with a refractive index detector,a UV detector (Agilent) set at 252 nm (optimal wavelength of absorbance of tbs) and a light scattering detector (Mini Dawn by Wyatt Technology). The flow rate was 1.0 ml/min. Only the UV chromatograms were taken into consideration for the determination of the conversion of tbs. The conversion of tbs has been determined from the area under tbs peak (see Figure S1). The comparison of this area at a reaction time t with the initial one at t = 0 s allowed the calculation of tbs conversion. Figure S1 Determination of tbs conversion by HPLC using the UV chromatogram Rheology Oscillatory shear measurement An AR2000 rheometer purchased from TA Instruments was used in this study. The apparatus was stress-imposed with cone-plate geometry. The geometry diameter was of 20 mm with a 4 angle and a truncation of 110 µm. The temperature was controlled by a Peltier system and a water bath. To prevent evaporation during the measurements, a solvent-trap was added. 7

8 2. NUMERICAL METHODS 2.1. Jaacks method to determine the reactivity ratio Reactivity ratios are usually determined using instantaneous forms of the copolymer composition equation (Mayo-Lewis equation), in which the co-monomer concentrations are assumed to remain constant. To be valid, this equation requires polymerizations to be stopped at low conversions. However, in living polymerizations, the reactivity ratios obtained at low conversion and the one determined for conventional radical polymerizations are not comparable. The main reason for it is that at low conversion, the polymer is dominated by oligomeric species which show significant chain length dependence on the rate constants of propagation 5. Equation (2.1) is the copolymer composition equation also known as Mayo-Lewis equation. = + + (2.1) The use of a large excess of one monomer (M 1 ) allows that monomer s reactivity ratio (r 1 ) to be evaluated using a simplified form of the Mayo-Lewis equation as depicted in equation (2.2): = (2.2) in which M 1 is the monomer in excess (acrylamide or acrylamide/amps in these experiments) and M 2 the minor monomer (tbs in these experiments). This expression is equivalent to the linear expression given in equation (2.3)(the Jaacks equation): = ln (2.3) To reduce the distortion of the error structure introduced by the use of logarithms, equation (2.3) was transformed to equation (2.4) 6 : 1 = 1 (2.4) By plotting the conversion of M 2 (X 2 ) as a function of the conversion of M 1 (X 1 ) and using non-linear least squares fitting, the reactivity ratio and its corresponding 95% confidence interval can be estimated. Although both conversions are subject to error, the error in X 1 was assumed to be negligible in relation to the error in X 2, due to the large excess of M Influence of SDS on the reaction rate of P(Am 80 -co-amps 20 ) copolymer As SDS is one of the major elements of the micellar polymerization system, it is crucial to understand its impact on the RAFT/MADIX polymerization of the hydrophilic monomers. The syntheses were carried out at 25 C over two hours following the protocol of Read et al. 1. The influence of the concentration of SDS was examined and was varied from 0 to 0.1 mol/l. In order to estimate the degree of control of the polymerization, kinetic studies have been performed. Molecular mass values were determined by aqueous SEC-MALS. 8

9 The reaction rate has been determined using a non-linear fit of conversion vs. time plots as described in equation (3.1): conversion=a 1 exp b time (3.1) where b corresponds to the reaction rate (see Figure S2 as example). The error bars are estimated using the 95% confidence band. 1,2 1,0 Conversion 0,8 0,6 0,4 0,2 0,0 time vs conversion Fit : f = a*(1 - exp(-b*x)) 95% Confidence Band Time (min) Figure S2 Determination of the reaction rate of the kinetics of P(Am 80-co-AMPS 20) synthesized in presence of SDS (C SDS=0.1 M) and mediated by Rhodixan A1 using a non-linear fit. Table S2 shows the evolution of the rate of Am polymerization with increasing concentration of SDS using PAm 7 -XA1 as the chain transfer agent. The reaction rate significantly decreases with increasing concentration of SDS. Similar trends were observed for both chain transfer agents. Table S2 Reaction rates of P(Am 80-co-AMPS 20) synthesized in presence of SDS (C SDS = mol/l) using Rhodixan A1 or PAm 7-XA1 as CTA (T=25 C). C SDS mol/l Rhodixan A1 Reaction rate mol.l -1.min -1 PAm 7 -XA ± ± ± ±

10 The influence of SDS on the number-average molecular weight (M n ) is depicted in Figure S Molecular weight Mn (kg/mol) C SDS =0.1 M ; Rhodixan A1 Figure S3 Effect of 0.1 M SDS on the evolution of number-average molecular weight (M n) of P(Am 80-co-AMPS 20) with conversion of AMPS and acrylamide in the presence of Rhodixan A1 or PAm 7-XA1. Solid lines correspond to linear fits of the data. 4. Determination of the reactivity ratio of P(Am 80 -co-amps 20 -co-tbs) copolymer The reactivity ratio determined was that of the monomer in large excess, i.e. the hydrophilic monomer, using the Jaacks method. In our case, the copolymerization contains both acrylamide and AMPS. Acrylamide and AMPS are near their azeotropic composition (r Am = 0.85, r AMPS = 0.18, f AMPS = at the azeotrope) and are consumed at approximately equal rates. Hence the composition of Am/AMPS doesn t change during the reaction and the acrylamide/amps mixture could be treated as a single monomer. An average reactivity ratio can be derived for the incorporation of tbs along the hydrophilic backbone. At high conversion, complete conversion of the hydrophobic monomer was observed, indicating its complete incorporation into the hydrophilic backbone. The Jaacks plot obtained for P(Am 80 -co-amps 20 -co-tbs) targeting 100 kg/mol is shown Figure S4 and gives a reactivity ratio r Am/AMPS equal to 1.1. In this case, addition of hydrophilic or hydrophobic monomers occurs with little selectivity. 0 0,0 0,2 0,4 0,6 0,8 1,0 Conversion 10

11 1,0 0,8 tbs conversion 0,6 0,4 0,2 0,0 0,0 0,2 0,4 0,6 0,8 1,0 global conversion Figure S4 Conversion of tbs as a function of global conversion. Solid line shows fit to data assuming r Am/AMPS of 1.1. Dashed lines show 95% confidence interval 0.8 <r Am< 1.4. The evolution of the conversion of hydrophilic and hydrophobic monomers with time for P(Am 79 -co- AMPS 20 -co-tbs 1 ) is shown in Figure S5. 1,0 0,8 Conversion 0,6 0,4 0,2 0, Time (min) Am/AMPS tbs Figure S5 Evolution of the conversion of Am/AMPS and tbs with time for P(Am 79-co-AMPS 20-co-tBS 1) associative copolymer with M n,th=100 kg/mol at 25 C. 11

12 The influence of tbs on the number-average molecular weight (M n ) targeting 10 and 100 kg/mol is depicted in Figure S Molecular weight (kg/mol) ,0 0,2 0,4 0,6 0,8 1,0 Conversion Figure S6 Evolution of the number-average molecular weight M n of P(Am 80-co-AMPS 20-co-tBS), P(Am 80-co- AMPS 20) for M n,th=100 kg/mol and P(Am 80-co-AMPS 20-co-tBS) for M n,th=10 kg/mol with the conversion of hydrophilic monomers using PAm 7-XA1 as chain transfer agent. Solid lines correspond to linear fits of the data. 12

13 5. LITERATURE (1) Read, E.; Guinaudeau, A.; James Wilson, D.; Cadix, A.; Violleau, F.; Destarac, M. Low Temperature RAFT/MADIX Gel Polymerisation: Access To Controlled Ultra-high Molar Mass Polyacrylamides. Polym. Chem. 2014, 5, (2) Candau, F.; Selb, J. Hydrophobically-modified Polyacrylamides Prepared By Micellar Polymerization. Adv. Colloid Interface Sci. 1999, 79, (3) Kujawa, P.; Audibert-Hayet, A.; Selb, J.; Candau, F. Effect Of Ionic Strength On The Rheological Properties Of Multisticker Associative Polyelectrolytes. Macromolecules. 2006, 39, (4) Kujawa, P.; Audibert-Hayet, A.; Selb, J.; Candau, F. Compositional Heterogeneity Effects In Multisticker Associative Polyelectrolytes Prepared By Micellar Polymerization. J. Polym. Sci. Part A Polym. Chem. 2003, 41, (5) Lad, J.; Harrisson, S.; Mantovani, G.; Haddleton, D. M. Copper Mediated Living Radical Polymerisation: Interactions Between Monomer And Catalyst. Dalt. Trans. 2003, 6, (6) Jaacks, V. A Novel Method Of Determination Of Reactivity Ratios In Binary And Ternary Copolymerizations. Die Makromol. Chemie, Rapid Commun. 1972, 161,