Functional Group Distribution and Gradient Structure. Resulting from the Living Anionic Copolymerization of. Styrene and para-But-3-enyl Styrene.
Supporting Information
for
Functional Group Distribution and Gradient Structure Resulting from the Living Anionic Copolymerization of Styrene and para-But-3-enyl Styrene
Adrian Natalello,†,‡ Arda Alkan,†,§ Philipp von Tiedemann,† Frederik R. Wurm*,§ and Holger Frey*,†
†
Institute of Organic Chemistry, Johannes Gutenberg-University (JGU), Duesbergweg 10-14,
55128 Mainz, Germany ‡
Graduate School Materials Science in Mainz, Staudinger Weg 9, D-55128 Mainz, Germany
§
Max Planck Institute for Polymer Research (MPI-P), Ackermannweg 10, D-55128 Mainz,
Germany
1
Experimental Details
Reagents. All solvents and reagents were purchased from Acros Organics or Sigma Aldrich and used as received unless otherwise mentioned. para-But-3-enyl styrene (pBuS) was synthesized as described previously.1 Chloroform-d1, DMSO-d6 and cyclohexane-d12 were purchased from Deutero GmbH. Cyclohexane was distilled from sodium/benzophenone under reduced pressure into a liquid nitrogen-cooled reaction vessel (cryo-transfer). Styrene (S), pBuS and cyclohexane-d12 were dried over calcium hydride (CaH2) and cryo-transferred prior to use. sec-Butyllithium (sec-BuLi, 1,3 M, Acros) was used as received.
Instrumentation. 1H NMR spectra (400 MHz) and
13
C NMR (100 MHz) were recorded on a
Bruker AMX400 spectrometer and were referenced internally to the residual proton signals of the deuterated solvent. For size exclusion chromatography (SEC) measurements in DMF (containing 0.25 g/L of lithium bromide as an additive) an Agilent 1100 Series was used as an integrated instrument, including a PSS HEMA column (300/100/40 g/mol), a UV detector (operating at 275 nm) and a RI detector. All molecular weights and molecular weight distributions determined by SEC were referenced to linear polystyrene (PS) standards provided by Polymer Standards Service (PSS). DSC curves were recorded on a Perkin-Elmer DSC 8500 in the temperature range from -100 to 100°C at heating rates of 10 K min−1 under nitrogen.
Poly(p-but-3-enyl styrene) (PpBuS, #1) 0.75 mL (3.89 mmol) of pBuS and 6.75 mL Cyclohexane were freshly purified and mixed inside an argon-filled glove box. To the vigorously stirred system 0.08 mL (0.10 mmol) sec-BuLi was 2
added via syringe at room temperature, and immediately the typical orange color of the living carbanions was observed. After 2.5 h the reaction was terminated with degassed methanol via syringe. The resulting polymer was precipitated in methanol at - 25 °C and dried under high vacuum (yield = 87%). 1H NMR (400 MHz, CDCl3, δ in ppm): 7.25-6.29 (m, aromatic resonances PpBuS), 6.05-5.78 (s, -CH=CH2), 5.19-4.89 (m, -CH=CH2), 2.90-2.52 (Ar-CH2), 2.52-0.87 (CH2 group of the butenyl group, CH2 CH initiator, PpBuS backbone), 0.86-0.53 (m, 6H, initiator). 13C NMR, see Figure S2.
Figure S1. SEC elugram (DMF) of PpBuS (#1)
Branching side reaction during the homo polymerization of para-but-3-enyl styrene
trace
reaction time / h
Black
2.5
Red
24
Yellow
48
Green
120
Blue
336 3
Table S1. Different reaction times for the polymerization of pBuS.
Figure S2. Overlay of several SEC elugrams (DMF) of the polymerization of pBuS after different reaction times (black: 2.5h, red: 24 h, yellow: 48 h, green 120 h, blue: 336 h)
Figure S3. 13C NMR (100 MHz) spectra of PpBuS obtained after 2.5 h and 336 h reaction time. 4
Poly(p-but-3-enyl styrene)-co-poly(styrene) (PpBuS-co-PS, #2-5) Exemplary Synthesis Procedure for PpBuS33-co-PS6.5 (#2). The polymerization of polymer #2 was carried out in analogy to the synthesis PpBuS (#1). 0.5 mL (2.59 mmol) pBuS, 0.06 mL (0.052 mmol) S and 5.6 mL of cyclohexane were mixed in an NMR tube. Subsequently the reaction was initiated by the addition of 0.06 mL (0.08 mmol) sec-BuLi at room temperature. After 2.5 h reaction time the polymerization was terminated with degassed methanol. The polymer was precipitated in cold (T = -25 °C) methanol (yield: 90%). 1
H NMR (400 MHz, CDCl3, δ in ppm): 7.24-6.21 (m, aromatic resonances of PpBuS and S),
5.99-5.72 (s, -CH=CH2), 5.16-4.89 (m, -CH=CH2), 2.85-2.46 (Ar-CH2), 2.52-0.81 (CH2 resonances of the butenyl group, CH2 CH initiator, PpBuS and S backbone), 0.81-0.53 (m, 6H, initiator).
Figure S4. SEC elugram (DMF) of PpBuS-co-PS (#2)
5
Figure S5. SEC elugram of PpBuS-co-PS (#3)
Figure S6. SEC elugram of PpBuS-co-PS (#4)
Figure S7. SEC elugram of PpBuS-co-PS (#5) 6
Thiol-ene addition of PS14-co-PpBuS3 (#4) with protected cysteine (PS14-co-(PpBuS-Cys)3, #6) 100 mg of polymer #4 (50.25 µmol) and 0.52 g of N-acetal-L-cysteine methyl ester (Cys) were dissolved in 2 mL of DMF. Oxygen was removed from the reaction mixture by three freezepump-thaw cycles and flushed with argon. Subsequently 0.172 g (0.001 mol) AIBN were added under a flow of argon and the reaction mixture was heated up to 75 °C for 24 h. The functionalized polymer was purified by dialysis (MWCO 1000 g/mol) against THF for 24 h (Yield: 56%).
Figure S8. SEC elugrams of thiol-ene addition.
1
H NMR Kinetics. A monomer solvent mixture (10 wt%) was prepared inside an argon-filled
glove-box (for purification established procedures were used previously). Then a conventional NMR tube was filled with the reaction mixture and sealed with a septum. The monomer mixture was measured separately in NMR to set all parameters (locking/ shimming procedures). Then 7
sec-BuLi was added to the mixture and the kinetic measurement was started with 4 scans per spectrum, a relaxation time of 1 s between the individual scans and increasing time intervals between two measurements ranging from 0 s to 42 s with increasing reaction time.
Additional equations: Copolymerization:
+
+
+
+
Pi: active chain end Mi: monomer kii: reactivity constant
Fineman Ross equation: 1−
∙ = − + Equation S1: Fineman Ross equation
x: mol fraction of the stock X: mol fraction of the Polymer at certain mole fraction of the stock
r1: reactivity ratio 8
=
Equation S2: Reactivity ratio r1
r2: reactivity ratio =
Equation S3: Reactivity ratio r1
Determination of the probability of comonomer incorporation vs. relative position in the polymer chains (Figure 2). The theoretical comonomer probability for an ideally random copolymerization is independent of the comonomer feed (dashed lines in Figure 2b). For the system pBuS and S it was calculated as follows: From the 1H NMR kinetics for each position in the polymer chain the respective comonomer concentrations can be calculated (as plotted in Figure 2a). The probability of the respective comonomer incorporation is calculated from the fit function of these values by the mol-fraction of incorporation (using the concentration between two consecutive concentrations).
REFERENCES (1)
Zhang, H.; Ruckenstein, E. Macromolecules. 1999, 32 (17), 5495–5500.
9
