Polymeric materials based on polyisobutylene and poly(poly(ethylene glycol) methacrylate) Ph. D. Theses Ákos Szabó Chemistry Doctoral School Synthetic Chemistry, Materials Science and Biomolecular Chemistry Program Eötvös Loránd University, Faculty of Science Head of Doctoral School: Prof. György Inzelt Head of Program: Prof. András Perczel Supervisor: Prof. Béla Iván Budapest 2014
I. Introduction and Aims The role of amphiphilic polymers is crucial in both the scientific and technical development of the 21st century due to their special properties and behaviour. These materials contain at least two types of polymer chain segments (generally a hydrophilic and a hydrophobic one) covalently coupled to each other. Although these materials can be synthesized with different structures, amphiphilic conetworks, in which the hydrophilic and hydrophobic polymer chains form a polymer network, have special interest. These materials show unique self-assembly behaviour, mainly with nanophase separation, different from that of the block copolymers. To synthesize amphiphilic polymers with tunable properties, generally the application of one of the living polymerization techniques is required. The main advantages of these processes are the well-defined chain length and the possibility of chain-end functionalization which provides the possibility for the coupling of the different type of chain segments. During my work, amphiphilic macromolecules containing polyisobutylene (PIB) and poly(poly(ethylene glycol) methacrylate) (PPEGMA) polymacromonomer segments with linear, branched and network structures were synthesized by the application of two living polymerization techniques, quasiliving carbocationic polymerization and atom transfer radical polymerization (ATRP). The thermal behaviour, structure, and in the case of conetworks the swelling properties of the obtained polymers in organic solvents and surfactant solutions were investigated. Network syntheses by other methods, appropriate for the preparation of conetworks and physically crosslinked films with improved mechanical properties were also investigated. II. Experimental Polyisobutylenes (PIB) were prepared by quasiliving carbocationic polymerization of isobutylene initiated by 5-tert-butyl-1,3-dicumyl chloride or 2-chloro-2,4,4-trimethylpentane in the presence of TiCl 4 Lewis acid and 1,1,4,4-tetramethylethylenediamine additive at -78 ºC. The polymerizations were quenched by allyltrimethylsilane to obtain allylic chain ends which were transferred to hydroxyl endgroups via hydroboration and subsequent oxidation under basic conditions. Finally, the hydroxyl groups were esterified with 2-bromoisobutyryl bromide which results in the formation of 2-bromoisobutyrate endgroups which can initiate ATRP. ATRPs were performed with CuCl/1,1,4,7,10,10-hexamethyl triethylenetetramine 1
(CuCl/HMTETA) catalyst in the presence of L-ascorbic acid in toluene at 40 ºC. Various PEGMA macromonomers with different molecular weights, i.e. (EG) 2 MA with 188 g/mol, PEGMA 300 with 300 g/mol and PEGMA 475 with 475 g/mol were polymerized using ATRP initiated by PIB macroinitiators. The resulting triblock copolymers were analyzed by 1 H NMR spectroscopy and gel permeation chromatography (GPC), and were used as macroinitiators of ATRP of bifunctional monomer ethyleneglycol dimethacrylate (EGDMA) to prepare conetworks which were characterized by swelling investigations, small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), atomic force microscopy (AFM) and thermogravimetric analysis (TGA). Conetworks with different structure were also prepared by free radical copolymerization of PEGMA and methacrylate-telechelic PIB. These conetworks were characterized by the same way mentioned above. ATRPs of methyl methacrylate initiated by PPEGMA-b-PIB-b-PPEGMA triblock copolymers were also performed, and from the obtained pentablock terpolymers polymer films were prepared. III. Results 1. Atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methacrylate (PEGMA) macromonomers were carried out by using macroinitiators obtained by chain end modification of telechelic polyisobutylene (PIB). In this way, different PPEGMA-b-PIB-b- PPEGMA triblock copolymers were obtained. It was found that high conversion can be reached with the CuCl/HMTETA catalyst and quite long reaction time (several days) in toluene at 40 ºC. The analysis results indicate the presence of slow initiation in this reaction due to the steric hindrance between the PIB macroinitiator and PEGMA macromonomer and the differences in the chemical environment of the chain ends. It was found that this slow initiation is negligible in the case of PEGMA with short side chains and at small PIB/PEGMA ratios. 2. PIB-PPEGMA amphiphilic polymer conetworks were successfully synthesized by ATRP of the bifunctional ethylene glycol dimethacrylate (EGDMA) initiated by PPEGMA-b-PIB-b- PPEGMA triblock copolymers as macroinitiators. A series of conetworks were prepared, in which the side chain length of PEGMA monomeric units, the EGDMA:chain end ratio and the 2
PIB:PPEGMA ratio were systematically varied. The obtained results allow to conclude that EGDMA:chain end ratio has no considerable effect on the gel fraction of conetworks which is mainly in the range of 60-75 wt%. PIB-PPEGMA amphiphilic conetworks were also synthesized by the macromonomer method, i.e. by the free radical copolymerization of PEGMA and methacrylate-telechelic PIB. In this case the gel fractions, independently of the PEG side chain length, were quite high, 92-95 wt%. 3. On the basis of results by small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and atomic force microscopy (AFM) investigations it was found that the new PIB-PPEGMA conetworks have nanophase-separated structure with average domain distances between 10 and 40 nm and cocontinuous morphology. The results of these structural characterizations also show that only the PEG side chain length has a considerable effect on the average domain distance which increases with increasing side chain length. 4. The swelling properties of the conetworks in water, hexane and toluene show that the PIB- PPEGMA conetworks swell in all of these three solvents which prove their amphiphilic character. The degree of swelling values in toluene cosolvent of the components are higher than in the case of the specific solvents, as expected. Although PPEGMA homopolymers show thermoresponsive behaviour in water, the swollen conetworks do not have sharp shrinkage in water at the LCST of the PPEGMA segments which indicates that these conetworks containing biocompatible PIB and PPEGMA segments are mechanically stable and can be applied in a wide temperature range. It was found that the degree of swelling of the conetworks in solutions of benzyl dimethyl tetradecylammonium chloride (BDMTDACl) cationic or sodium dodecyl sulphate (NaDS) anionic surfactants increases with increasing surfactant concentration due to the interaction between the surfactants and the polymeric components of the conetworks. This increase is reversible in the case of NaDS while irreversible binding of surfactant was be observed with BDMTDACl. 5. Coupling of PPEGMA-b-PIB-b-PPEGMA triblock copolymers can also be achieved by photocuring or iron-catalyzed ATRP. A star-shaped polymer was also synthesized with the PIB-b-PPEGMA diblock copolymer which was used as macroinitiator in the ATRP of 3
EGDMA bifunctional monomer. These experiments demonstrate the possibilty to obtain a large variety of PIB-PPEGMA macromolecular systems with unique structures and properties. 6. ATRP of methyl methacrylate (MMA) initiated by PPEGMA-b-PIB-b-PPEGMA triblock copolymers was performed, and such a way PMMA-b-PPEGMA-b-PIB-b-PPEGMA-b- PMMA pentablock terpolymers were obtained, from which mechanically stable films can be made. On the basis of SAXS and AFM investigations it can be concluded that in the case of PPEGMA blocks with short side chains lamellar morphology is formed via nanophasic selfassembly. However, in the case of longer PEG side chains, unordered nanophases are present in the pentablock terpolymers. IV. Importance of the new results During my PhD work, I studied the synthetic possibilities and properties of linear and starshaped polymers and polymer networks containing covalently coupled PIB and PPEGMA segments. The motivation of this research was the biocompatibility of both segments as homopolymers and the special properties of the amphiphilic polymers containing these segments in various macromolecular assemblies. Moreover, the hydrophilic PPEGMA segments have interesting properties, such as comb-like shape and thermoresponsive behaviour in water. These complex macromolecular structures were synthesized by coupling of two living polymerization techniques, quasiliving carbocationic and atom transfer radical polymerization which make preparation of well-defined polymers possible. The obtained new results can be utilized for instance in the synthesis of novel, well-defined amphiphilic medical implant coatings or templates in nanotechnology etc. V. List of publications Publications 1. Bingöl, B., Strandberg, C., Szabó, Á., Wegner, G.: Copolymers and Hydrogels Based on Vinylphosphonic Acid Macromolecules, 2008, 41(8), 2785-2790. IF: 4.407 4
2. Szabó, Á., Iván, B.: Polyisobutylene poly(poly(ethylene oxide) (meth)acrylate) block copolymers and conetworks Studia Universitatis Babes-Bolyai, Seria Chemia, 2009, Special Issue 2, 123-134. IF: 0.086 3. Iván B., Fodor Cs., Haraszti M., Kali G., Kasza Gy., Mezey P., Osváth Zs., Pálfi V., Pásztor Sz., Soltész A., Szabó Á., Szabó S., Szanka I., Szarka Gy., Verebélyi K.: Makromolekuláris építészet funkciós polimerekkel: szintézisük, reakcióik és alkalmazási lehetőségeik a nanovilágtól a katalízisen át a gyógyászatig Magyar Kémikusok Lapja, 2012, 67, 138-140. 4. Verebélyi, K., Szabó, Á., Iván B.: Quasiliving atom transfer radical polymerization of styrene and n-butyl acrylate as non-fluorous monomers in a fluorinated solvent, benzotrifluoride Polymer, 2012, 53, 4940-4946. IF: 3.438 5. Szabó, Á., Szarka, Gy., Iván, B.: Synthesis of Poly(poly(ethylene glycol) methacrylate) Polyisobutylene ABA Block Copolymers by the Combination of Quasi-living Carbocationic and AtomTransfer Radical Polymerizations Macromolecular Rapid Communications, in press DOI: 10.1002/marc.201400469 IF: 4.608 6. Szabó, Á., Wacha, A., Thomann, R., Szarka, Gy., Bóta, A., Iván, B.: Synthesis of Poly(methyl methacrylate)-poly(poly(ethylene glycol) methacrylate)- polyisobutylene ABCBA Pentablock Copolymers by Combining Quasiliving Carbocationic and Atom Transfer Radical Polymerizations and Characterization Thereof Journal of Macromolecular Science, Pure and Applied Chemistry, in press IF: 0.740 Proceedings 1. Szabó Á., Groh W. P., Szesztay A., Iván B.: Poliizobutilén láncvégi reakciói különleges tulajdonságú adalékanyagok jelenlétében, kváziélő karbokationos polimerizációs körülmények között (in Hungarian) Proceedings, 14th International Conference on Chemistry, Kolozsvár (Cluj-Napoca), Romania, 13-15. November 2008, pp. 331-335. 2. B. Iván, A. Domján, G. Erdődi, Cs. Fodor, M. Haraszti, G. Kali, P. Mezey, Á.Szabó, S. L. Szabó, I. Szalai, R. Thomann, R. Mülhaupt: Smart Nanostructured Amphiphilic Polymer Conetworks Polym. Mater. Sci. Eng., 2009, 101, 925-926. 5
3. Szabó Á., Iván B.: Különleges hatású adalékanyagok poliizobutilén láncvégen kiváltott reakciói kváziélő karbokationos polimerizációs körülmények között (in Hungarian) Proceedings, 23rd Presentations Days of Chemistry, Szeged, 26-28 October 2009 (ISBN 978 963 482 969 0) pp. 52-53. 4. Szabó Á., Iván B.: Poliizobutilén-poli(poli((etilén-oxid)-(met)akrilát) blokk-kopolimerek és kotérhálók előállítása (in Hungarian) Műszaki Szemle, 2009, 48, 34-41. 5. Szabó Á., Iván B.: Poliizobutilén és poli(poli(poli(etilén-oxid)-metakrilát) alapú amfifil kotérhálók előállítása és vizsgálata (in Hungarian) Proceedings, 16th International Conference on Chemistry, Kolozsvár (Cluj-Napoca), Romania, 11-14 November 2010 (ISSN 1843-6293) pp. 101. 6. Szabó Á.; Iván B.: Synthesis of Poly(poly(ethylene oxide) methacrylate)-polyisobutylene Amphiphilic Conetworks Proceedings, Workshop Career in Polymers II, Prague, July 23-24, 2010. (ISBN 978-80-85009-62-0) pp. 13. 7. Á. Szabó; B. Iván: Synthesis of Poly[poly(ethylene oxide) methacrylate]-poly(isobutylene) Block Copolymers Proceedings, Contemporary Ways to Tailor-made Polymers Modern Methods of Polymer Synthesis Prague; Czech Republic; July 18-22, 2010 (ISBN 978-80-85009-63-7) pp 92 8. B. Iván, V. Pálfi, Á. Szabó, P. Mezey, R. Thomann, R. Mülhaupt: Functional Polyisobutylenes as Versatile Polymers: From oil Additives to Novel Biomaterials and Nanostructures Macromolecular Rapid Communications (ISSN: 1022-1336) 32: pp. F35-F37. (2011) 9. B. Iván, Cs. Fodor, M. Haraszti, G. Kali, Sz. Pásztor, G. Erdődi, A. Domján, Á. Szabó, S. Szabó, R. Thomann, R. Mülhaupt: Smart nanostructured amphiphilic polymer conetworks: a new material platform for responsive gels with enhanced and tunable properties Polym. Mater. Sci. Eng., 2012, 107, 211-212. Presentations 1. Szabó Á. Poliizobutilén-poli(etilén-oxid) blokk-kopolimerek szintézise kváziélő karbokationos és atomátadásos gyökös polimerizáció összekapcsolásával (in Hungarian) ELTE Scientific Students' Association Conference, 22 November 2008 6
2. Szabó Á. Poliizobutilén-poli(etilén-oxid) blokk-kopolimerek szintézise kváziélő karbokationos és atomátadásos gyökös polimerizáció összekapcsolásával (in Hungarian) National Scientific Students' Association Conference, Debrecen, 6-8 April 2009 3. Szabó Á., Iván B.: Poliizobutilén-poli(poli(etilén-oxid)-metakrilát) blokk-kopolimerek és kotérhálók (in Hungarian) Symposium of the Division of Plastics and Natural Polymers of the Hungarian Academy of Sciences, Budapest, 23 April 2009 4. Szabó Á., Iván B.: Poliizobutilén-poli(poli(etilén-oxid)-(met)akrilát) blokk-kopolimerek és kotérhálók előállítása (in Hungarian) 15th International Conference on Chemistry, Marosvásárhely (Targu Mures), Romania, 12-15 November 2009 5. Szabó Á., Iván B.: Poliizobutilén-poli(poli(etilén-oxid)-metakrilát) blokk-kopolimerek mint potenciálisan új bioanyagok szintézise (in Hungarian) Scientific Days of Chemical Research Center of the Hungarian Academy of Sciences, 24-26 November 2009 6. Szabó Á., Iván B. Poliizobutilén-poli(poli(etilén-oxid)-(met)akrilát) blokk-kopolimerek szintézise kváziélő karbokationos és atomátadásos gyökös polimerizáció összekapcsolásával (in Hungarian) Chemical Research Center of HAS, 13th PhD School, Balatonkenese, 21-23 April 2010 7. Lórántfy L., Pálfi V., Szabó Á., Iván B.: Aldehid láncvégű poliizobutilén szintézise allil-klorid végcsoport ozonolízisével (in Hungarian) Chemistry Conference of the Hungarian Chemical Society, Hajdúszoboszló, 30 June - 2 July 2010 (ISBN 978-963-9970-05-2) (poster) 8. Á. Szabó, B. Iván: Synthesis of Poly(Poly(Ethylene Oxide) Methacrylate)-Polyisobutylene Amphiphilic Conetworks 74th Prague Meeting on Macromolecules, Contemporary Ways to Tailor-made Polymers: Modern Methods of Polymer Synthesis, Prague, Czech Republic, 18-22 July 2010 (poster) 9. Á. Szabó, B. Iván: Synthesis of poly(poly(ethylene oxide) methacrylate)-poly(isobutylene) block copolymers Workshop Career in Polymers II, Prague, Czech Republic, 23-24 July 2010 7
10. L. Lorántfy, V. Pálfi, Á. Szabó, B. Iván: Synthesis of Aldehyde-Capped Polyisobutylene by Ozonolysis of Allyl Chloride- Terminated Polyisobutylene 3rd EuCheMS European Chemistry Congress, Nürnberg, Germany, 29 August 2010 (poster) 11. Á. Szabó, B. Iván: Synthesis of Polyisobutylene-Poly(Poly(Ethylene Oxide) Methacrylate) Amphiphilic Block Copolymers 3rd EuCheMS European Chemistry Congress, Nürnberg, Germany, 29 August 2010 (poster) 12. Szabó Á., Iván B.: Poliizobutilén és poli(poli(poli(etilén-oxid)-metakrilát) alapú amfifil kotérhálók előállítása és vizsgálata (in Hungarian) 16th International Conference on Chemistry, Kolozsvár (Cluj-Napoca), Romania, 11-14 November 2010 (poster) 13. Szabó Á., Iván B.: Poliizobutilén és poli(poli(etilén-oxid)-metakrilát) szegmenseket tartalmazó újfajta polimer szerkezetek előállítása (in Hungarian) 1st National Conference of the Hungarian Chemical Society, Sopron, 22-25 May 2011 (poster) 14. Szabó Á.: Poliizobutilén és poli(poli(etilén-oxid)-metakrilát) szegmensekből felépített különleges polimer rendszerek előállítása (in Hungarian) Erika Kálmán PhD Student Conference, Budapest, 27 May 2011 15. Szabó Á., Érsek G., Iván B.: Poliizobutilén és poli(poli(etilén-oxid)-metakrilát) alapú makromolekuláris szerkezetek, mint potenciális új bioanyagok előállítása (in Hungarian) 9th Winter School: Biomaterials, Biocolloids and Biophysics, Salgóbánya, 7-10 March 2012 16. G. Érsek, Á. Szabó, Gy. Inzelt, B. Iván Synthesis and characterisation of polyaniline interpenetrating in amphiphilic conetworks Career in Polymers IV Workshop, Prague, Czech Republic, 29-30 June 2012 18. G. Érsek, Á. Szabó, B. Iván Synthesis and characterisation of amphiphilic polymer conetworks based on polyisobutylene and poly(di(ethylene glycol) methyl ether methacrylate) 76th Prague Meeting on Macromolecules, Polymers in Medicine, Prague, Czech Republic, 1-5 July 2012 (poster) 19. Á. Szabó, G. Érsek, B. Iván Polyisobutylene-Poly(Poly(Ethylene Oxide) Methacrylate) Amphiphilic Conetworks: Behaviour in Aqueous Solutions 10th Conference on Colloid Chemistry, Budapest, 29-31 August 2012 8
20. Szabó Á.: Poliizobutilén és poli(poli(etilén-glikol)-metakrilát) alapú amfifil makromolekulák előállítása (in Hungarian) Erika Kálmán PhD Student Conference, Mátraháza, 18-20 September 2012 21. Á. Szabó, G. Érsek, A. Domján, Cs. Fodor, G. Kali, Gy. Kasza, T. Marek, B. Németh, B. Pásztói, Sz. Pásztor, T. Stumphauser, K. Süvegh, K. Verebélyi, B. Iván Functional Polymers Obtained by Quasiliving Cationic Polymerizations as Building Blocks of Novel Macromolecular Architectures IUPAC International Symposium of Ionic Polymerization 2013, Awaji Yumebutai, Japan, 23-28 September 2013 22. Szabó Á.: Poliizobutilén és poli(poli(etilén-glikol)-metakrilát) alapú makromolekuláris anyagi rendszerek (in Hungarian) Seminar of the Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, 1 April 2014 (PhD predefense) 9