upplementary Information: Hyperbranched Polymers by Thiol-Yne Chemistry, From mall Molecules to Functional Polymers. Dominik Konkolewicz 1, Angus Gray-Weale 2, ébastien Perrier -1, * 1 Key Centre for Polymers and Colloids, chool of Chemistry, Building F11, University of ydney, NW, 2006, Australia, 2 chool of Chemistry, Monash University, Victoria 3800, Australia. Experimental methods Chemicals All reagents were used as obtained unless otherwise stated. Prop-2-yl-1-ol, 2,2- dimethoxy-2-phenyl-acetophenone (DMPA), isopropyl amine, (3-dimethylaminopropyl)- ethylcarbodiimide (EDC), 4-(dimethylamino)pyridine (DMAP), styrene and 2,2'- Azobisisobutyronitrile (AIBN) were purchased from Aldrich. AIBN was recrystallized from ethanol, and styrene was passed over basic alumina to remove the inhibitor. 3- mercaptopropionic acid was purchased from Merck. ulphuric Acid and triethylamine were purchased from Ajax chemicals. N,N-dimethyl formamide was purchased from Fluka. 2-(butylthiocarbonothioylthio)propanoic acid or (propanoic acid)yl butyl trithiocarbonate (PABTC) was received from Dulux Australia. Nuclear Magnetic Resonance (NMR) All NMR analysis was performed on a Bruker AVANCE200 NMR pectrometer, with an xford narrow bore magnet and 5mm dual(ch) probes with z-gradients. NMR analysis was performed on the XWINNMR3.5 and inmr 0.7 software. Mass-pectrometry (M) All M analysis was performed on a ThermoFinniganPolarisQ quadrupole ion trap massspectrometer, using electron impact ionisation. The mass spectrometer was connected to a Trace 2000 Gas Chromatography ystem. -1
Triple Detection ize Exclusion Chromatography (EC) Molecular weights were determined using a Polymer Laboratories GPC-50-Plus EC system with a Polymer Laboratories PG-Gel 5µM guard column and two Polymer Laboratories Mixed-C columns. The system was equipped with a PL-RI Differential Refractive Index detector (DRI), PL-BV 400RT Viscometer (Visc), and a Precision Detectors PD2020 Light cattering Detector (L). The eluent was THF at a flow rate of 1 ml/min. The system was calibrated using Polystyrene standards with molecular weights in the range of 277000-265 g/mol. All analysis was performed using the Cirrus oftware, employing both Universal Calibration (UC) and Triple-Detection (TD). ize Exclusion Chromatography with UV Absorbance Detection The removal of the trithiocarbonate group from the RAFT synthesized polymers was confirmed using a himadzu EC system equipped with a Polymer Laboratories 10 µm guard column, two Polymer Laboratories Mixed-B columns, and both differential refractive index detection (himadzu, RID-10A) and UV detection(himadzu, PD-10A) set at 300nm. Tetrahydrofuran at 40 ºC was used as the eluent at a flow rate of 1 ml/min. ynthesis of prop-2-ynyl 3-mercaptopropanoate (PYMP). H prop-2-yn-1-ol H H 3-mercaptopropanoic acid H 2 4 prop-2-ynyl 3-mercaptopropanoate (PYMP) cheme 1. ynthesis of PYMP, a small molecule bearing a thiol and alkyne. Prop-2-yn-1ol (Aldrich, 7.16g, 127.4 mmol) was added to 3-mercaptopropionic acid (2.75g, 25.9 mmol). To this solution sulphuric acid (0.76g 7.8 mmol) was added and the solution was heated at 85 ºC for 2 hours. The solution was cooled to room temperature and left to sit for 1 hour. The reaction mixture was dissolved in 30 ml of dichloromethane, and triethylamine (3.0 g, 29.7 mmol) was added to this solution. This H -2
mixture was washed four times with 20 ml of water. The crude product was purified by silica gel chromatography using an eluent of 80% hexane and 20% ethyl acetate. The final impuritities were removed by passing the pruduct over a short silica column using 100% hexane as an eluent. This reaction is shown in cheme 1. This yielded pure PYMP (0.49g). The purity of the product (PYMP) was confirmed using both proton NMR, carbon NMR, and subsequently Mass-pectrometry. 1 H-NMR(200 MHz, CDCl 3 ) δ ppm 2.48 (1H, t, J = 4.95 Hz, H-C C) 4.71 (2H, d, J = 2.48 Hz, C C-CH 2 -), 1.65 (1H, t, J = 8.31 Hz, H) and 2.74 (4H, m, C()-CH 2 -CH 2 -). 13 C-NMR(200 MHz, CDCl 3 ) δ ppm 75.52 (H-C C),77.71 (H-C C), 52.57 (C C-CH 2 -), 171.17 (-C()- CH 2 ), 38.66 (C()-CH 2 -CH 2 ) and 20.00 (CH 2 -CH 2 -H). GC-M: 145.35 g/mol (expected 144.19 g/mol; The shift by 1 g/mol is likely to be due to deuteration of the thiol during NMR analysis) PhotoPolymerization of PYMP PYMP(201mg, 1.39 mmol) was mixed with DMF (296.5 mg, 4.06 mmol) and DMPA(6.1 mg, 0.024 mmol) was added to the stock solution. This solution was divided into 4 glass vials, and each vial was capped with a rubber septum. Each vial was wrapped in aluminium foil and degassed by bubbling nitrogen for 10 min. The Vials were placed under a UV lamp for their allotted time (10 min, 20min, 40min and 90 min). All reactions were performed in a dark box illuminated by a pectroline ENF-280C/FE lamp irradiating at 365 nm. After the allotted reaction time, each vial was exposed to air, and the sample was analysed by NMR and EC. Conversion was determined by integrating both the unreacted and reacted propargyl ester region in the NMR (4.1-4.8 ppm) and comparing this to the integral of the unreacted propargyl ester(4.6-4.7 ppm). ince each alkyne can react with 2 thiols conversion is given by the following formula -3
Conversion = 2 I A I U. Where I I A is the integral under both the reacted and unreacted A propargyl esters, while I U is the integral under just the unreacted ester. Molecular weights were determined by EC using both Universal Calibration and Triple detection. ynthesis of (prop-2-ynyl propanoate)yl butyl trithiocarbonate (PYPBTC) RAFT agent H H EDC DMAP DCM prop-2-yn-1-ol PABTC cheme 2. ynthesis of the RAFT agent PYPBTC. PYPBTC PABTC (1.030g) was dissolved in 50 ml of DCM and the solution was cooled to 0 ºC. Prop-2-yn-1-ol(1.21g) was added and the mixture. To this solution EDC(1.65g) and DMAP(0.5521g) were added. The solution was stirred at 0 ºC for 2h and then at ambient temperature overnight. This gave the crude product prop-2-ynyl 2- (butylthiocarbonothioylthio)propanoate or (prop-2-ynyl propanoate)yl butyl trithiocarbonate (PYPBTC). The crude PYPBTC was washed with deionized water (4 30 ml then 2 50 ml), and passed over a pad of silica using an eluent of 90% toluene and 10% ethyl acetate. The first fraction was collected and dried under vaccum to yield the product PYPBTC(1.08g at 72% yield) as a dark yellow liquid. This reaction is shown in cheme 2. The purity of the product was confirmed by proton NMR. 1 H- NMR(200MHz, CDCl 3 ) δ ppm, 2.509 (1H, t, J = 2.46 Hz, H-C C), 4.744(2H, d, 2.14 Hz, C C-CH 2 -) 4.871 (1H, q, J = 7.38 Hz, C()-C()H-CH 3 ), 1.485 (3H, d, J = 7.39 Hz, C()H-CH 3 ) 3.384(2H, t, J = 7.23 Hz, -CH 2 -CH 2 ), 1.71 (2H, q, J = 7.61 Hz, -CH 2 - CH 2 -CH 2 ), 1.429 (2H, s, J =7.95 Hz, CH 2 -CH 2 -CH 3 ) 0.953(3H, t, J = 7.24 Hz CH 2 -CH 3 ). -4
RAFT polymerization of tyrene PYPBTC (0.2014g, 0.729 mmol) and AIBN(0.0137g, 0.0825 mmol) were added to a flask equipped with a magnetic stirrer. To this solution, styrene (3.0427 g, 29.256 mmol) was added and the flask was capped with a rubber septum. This gave a ratio of tyrene:pypbtc:aibn of 40:1:0.11. xygen was removed from the solution by bubbling nitrogen gas for 10 min. The solution was polymerized at 60 ºC for 7.5 h, after which it was exposed to oxygen. Conversion was found by H-NMR, and the molecular weight determined by EC using universal calbration. The presence of the trithiocarbonate group was confirmed using an EC system equipped with a UV detector set at 300 nm. The residual styrene monomer was removed under reduced pressure. This afforded the alkyne terminated polystyrene trithiocarbonate. AIBN ( NH 2 ) n THF ( H ) n tyrene PYPBTC cheme 3. ynthesis of a polystyrene bearing a thiol and alkyne (ATPT). Alkyne-Terminated Polystyrene Thiol Aminolysis of Alkyne-Terminated Polystyrene-Trithiocarbonate. Alkyne terminated polystyrene trithiocarbonate(0.72 g) was dissolved in THF(5 ml) and placed in a flask equipped with a magnetic stirrer. Nitrogen gas was bubbled through this solution for 10 min. Isopropyl amine (1.81g, 30.6 mmol) was bubbled with nitrogen and added by a syringe to the Polystyrene-THF solution. This solution was stirred at ambient temperature for 40h. The removal of the trithiocarbonate group was confirmed using an EC system equipped with a UV detector set at 300 nm. The THF and residual isopropyl amine were removed under reduced pressure, and the product dissolved in a minimal amount of DCM. Methanol was cooled to 78 ºC, and the Polymer-DCM solution was -5
added dropwise to give the Alkyne-Terminated Polystyrene-Thiol (ATPT). cheme 3 shows the RAFT polymerization of styrene, and aminolysis to give the product ATPT. The polymer was analysed by H-NMR and EC. Photopolymerization of Alkyne-Terminated Polystyrene-Thiol (ATPT) Alkyne-terminated polystyrene-thiol (80.3 mg) was dissolved in DMF(175.7 mg, 2.405 mmol). To this solution DMPA(4.2 mg, 16 µmol) was added and the solution was wrapped in foil. This solution was divided into four vials, each wrapped in foil. Each vial was capped with a rubber septum and each vial degassed by blowing nitrogen gas. The vials were irradiated by UV radiation at 365nm for an allotted time (10 min, 20min, 40min, 90min). Each sample was analysed by H-NMR and Triple Detection EC. The sample taken at 180 min was prepared by dissolving alkyne-terminated polystyrene-thiol (20.8 mg) into DMF(44.6 mg, 0.611 mmol). To this solution DMPA(1.2 mg, 4.7 µmol) was added. The vial was wrapped in foil and capped with a rubber septum and degassed by blowing nitrogen gas. This vial was irradiated by UV radiation at 365nm for 180 min and analysed by H-NMR and Triple Detection EC. Conversion was determined from the NMR data. In the unreacted polymer we observe the CH 2 peak due to the propargyl ester linkage at (4.55-4.2 ppm), and upon irradiation peak appear at 4.65-4.85 ppm. Conversion = 2 I A I U, where I I A is the integral under both the reacted and unreacted A propargyl esters, while I U is the integral under just the unreacted ester. Molecular weights were determined by EC using both Universal Calibration and Triple detection. upplementary Results for the Photopolymerization of PYMP Figure 1 shows the viscometric and Light cattering (L) responses for the photopolymerization of PYMP after different times under the UV lamp. In general, the viscometer signal has a good signal to noise ratio, while the signal to noise ratio in the L -6
is poor, and no peak could be distinguished for the sample after 10 min of UV irradiation. Both the viscometric and L traces show the presence of high molecular weight species at low retention time. These results confirm conversion of PYMP to a high molecular weight hyperbranched polymer. Table 1 summarises the conversion and molecular weight data at 10, 20, 40 and 90 min. Figure 1. Evolution of the Viscometer response(left) and 90º Light cattering signal(right) for the photopolymerization of PYMP. Time (min) Conversion M n (UC) M w (UC) M w (TD) Dispersity Index (M w (UC)/M n (UC)) 10 0.69 562 2411 4.29 20 0.89 1105 8319 7267 7.52-7
40 0.94 1291 11407 10108 8.83 90 0.99 1496 17869 17094 11.94 Table 1. Table showing a summary of conversion and molecular weight data over time for the photopolymerization of PYMP. upplementary Data regarding the Preparation of ATPT Figure 2 shows the UV absorbance of the polystyrene as a function of the EC retention time. The trace UV (RAFT) shows the UV absorbance at 300 nm of the polystyrene mediated by the PYPBTC RAFT agent. The strong absorbance in the UV is due to the trithiocarbonate at the end of the polystyrene chain. The trace UV (H) shows the UV absorbance of the polymer after aminolysis. The UV signal after aminolysis is very small, showing the successful conversion of the trithiocarbonate group to a thiol. To directly compare the UV absorbance traces, the height of the polymer s DRI signal after aminolysis was matched to the height of the DRI signal before aminolysis. The UV trace after aminolysis was scaled by the same factor, which gives the trace UV(H). Figure 2. UV signal of polystyrene before (RAFT) and after (H) aminolysis. upplementary Data regarding the Photopolymerization of ATPT Figure 3 shows the evolution of the NMR trace of ATPT at different irradiation times. We see a decrease in the relative height of the peaks at about 4.2-4.5 ppm, and the appearance of broad peaks at about 5.6-5.8 ppm. We also observe negligible signal in the -8
alkene region of the NMR which suggest the formation of a polymer with very high degree of branching. This mechanism is qualitatively similar to the photoreaction of PYMP, since there is minimal alkene signal. This sugggests that the addition of a sulfur radical to the alkyne is slower than the addition of the sulfur radical to the alkene formed by the first addition. In the final sample (180 min) there appears to be a very small peak at 5.3 ppm, which may be a small amount of alkene. However, this peak s area is much smaller than the area under the fully saturated and fully unsaturated species (4.2-4.8 ppm), which again suggests minimal alkene species, and very high degrees of branching. Analysing the ATPT system is more difficult than the PYMP system since the polymer peaks are broad form the beginning and the fact that the NMR shifts upon conversion of the alkyne to alkane are quite small. However, we observe qualitative similarities between these two systems, suggesting that the mechanism of reaction is the same. Figure 4 shows the viscometric and L response for the photopolymerization of ATPT. The signal to noise ratio in the L trace for the photopolymerization is ATPT is much better than the signal to noise ratio for PYMP. This is most likely because of the high dn/dc of polystyrene in THF. Both the viscometric and L traces show the formation of high molecular weight species as the reaction progresses. These confirm the formation of hyperbranched polymers by the Thiol-Yne reaction. Table 2 shows the conversion, number and weight-averaged molecular weights for the photopolymerization of ATPT. -9
Figure 3. UV signal of polystyrene before (RAFT) and after (H) aminolysis. Figure 4. Evolution of the viscometer signal(left) and of 90º Light cattering signal (right) for the photopolymerization of ATPT. Dispersity Index Time(min) conversion Mn (UC) Mw(UC) Mw(TD) (Mw(UC)/Mn(UC)) 0 0 735 787 1.07 10 0.166 956 2230 2559 2.33-10
20 0.376 1085 3004 3430 2.76 40 0.544 1375 7508 7194 5.46 90 0.804 1789 19493 21215 10.90 180 0.954 2560 41787 43657 16.32 Table 2. Table showing a summary of conversion and molecular weight data over time for the photopolymerization of ATPT. -11