/department of chemical engineering and chemistry 1/24 Thermoreversible crosslinking of maleic anhydride-grafted ethylene-propylene copolymers An evaluation of hydrogen bonded and ionic networks Sun Chunxia March 2005 Coaches: Mark van der Mee Han Goossens

/department of chemical engineering and chemistry 2/24 Contents 1)Introduction: crosslinking of rubbers 2)Objectives 3)Modification with alkylamines - Preparation - Results - Conclusions 4)Modification with metal acetylacetonates -Preparation -Results -Conclusions 5)Future work

/department of chemical engineering and chemistry 3/24 Crosslinking of rubbers Crosslinking transforms non-elastic base material into an elastic material Two main commercial technologies: 1) Sulphur vulcanisation: 2) Peroxide curing Why? How?

/department of chemical engineering and chemistry 4/24 Crosslinking of rubbers Prevents processing in the melt Complicates recycling of scrap & used products Problems: х

/department of chemical engineering and chemistry 5/24 Thermoreversible crosslinking Thermoreversible crosslinking of rubbers: Low temperature: crosslinked material High temperature: crosslinks weaken or disappear Result: A crosslinked elastomer at service temperature that can be processed at elevated temperatures! heating cooling

/department of chemical engineering and chemistry 6/24 Crosslinking of rubbers Microphase separation into MAn-rich domains –Driving force is strong attraction between MAn groups and strong repulsion between polar MAn groups and apolar EPM chains –Domains act as physical crosslinks, increasing network density

/department of chemical engineering and chemistry 7/24 Thermoreversible crosslinking Multiple Hydrogen Bonding Triple Hydrogen Bonding unit Ionomer Quadruple Hydrogen Bonding unit Reversible ester XL formation Diels-Alder reaction Reversible amide XL formation Metal-Ligand complex Several thermoreversible crosslinking techniques

/department of chemical engineering and chemistry 8/24 Thermoreversible crosslinking Previous work in this project So far, pure HB is very weak !

/department of chemical engineering and chemistry 9/24 Thermoreversible crosslinking How to improve it ? (1)Combination with ionic interactions (2)Arrays of HB: Ureidopyrimidinones (UPy’s) (E.W. Meijer et al.)

/department of chemical engineering and chemistry 10/24 Objectives 1)Modification of MAn-g-EPM with primary amines to an amide-salt Significantly improves properties with NH 3, which is highly volatile DECREASE IN PROPERTIES Imide formation will occur at elevated temperatures DECREASE IN PROPERTIES 2) Addition of metal acetylacetonates (MeAA) to MAn-g-EPM based imides Modification of MAn-g-EPM with 3-amino-1,2,4-triazole (ATA) only slightly improves the properties Addition of different MeAA to the ATA-imide introduces ionic interactions Objectives ATA  Use less volatile primary amines (C 3, C 6, C 10, C 18 )  Study the mechanism for different metals (Co & Zn) and different imides

/department of chemical engineering and chemistry 11/24 Results (I)-Alkylamines Compression moulding at 180 ºC for 20 minutes Modification of maleic anhydride-grafted EPM with alkylamines Preparation Solution in THF at R.T.

/department of chemical engineering and chemistry 12/24 Results (I)- Alkylamines Peak position (cm -1 ) Peak assignment 1865 Anhydride 1785 Anhydride 1710 Acid 1640 Amide I 1555 Amide II Synthesis 1 eq Alkylamine

/department of chemical engineering and chemistry 13/24 Results (I)- Alkylamines FTIR spectra hexylamine modified MAn-g-EPM FTIR spectra octadecylamine modified MAn-g-EPM Different ratios

/department of chemical engineering and chemistry 14/24 C 10 > C 18 > C 3 > C 6 Results (I)- Alkylamines Significant improvement in tensile properties Trends in TS and modulus not consistent with alkyl length Two competing effects: Long tails disturb aggregate formation - poor properties Long tails can crystallize - improved properties Tensile tests 1 eq Alkylamine

/department of chemical engineering and chemistry 15/24 Results (I)- Alkylamines hexylamine octadecylamine Modulus and TS increase with increasing amount of alkylamine C 18 > C 6 crystallization? Different ratios

/department of chemical engineering and chemistry 16/24 Results (I)- Alkylamines Imide formation gives poor properties Poor properties of C 18 -imide: No significant crystallization! Imide of alkyl-amide acids

/department of chemical engineering and chemistry 17/24 Results (I)- Alkylamines FTIR spectroscopy can be used to study reaction of MAn-g-EPM with amines Modification with different primary amines improves the tensile properties significantly Modulus and TS increase with increasing amount of alkylamine Imide formation leads to poor properties Conclusions

/department of chemical engineering and chemistry 18/24 Results (II)- Metal acetylacetonates Metal acetylacetonate (CoAA or ZnAA) added to imide (ATA or C 3 ) in THF at RT Definition of 1 eq and 2 eq MeAA: 1 eq MeAA: adding enough metal to coordinate with all the oxygen atoms from the imide groups, assuming a fourfold coordination 2 eq MeAA: adding the double amount of metal HB with ionic interaction systems Preparation

/department of chemical engineering and chemistry 19/24 Results (II)- Metal acetylacetonates 1 eq MeAA to ATA-imide2 eq MeAA to ATA-imide Tensile tests

/department of chemical engineering and chemistry 20/24 Results (II)- Metal acetylacetonates 1 eq of MeAA to propylimide 2 eq of MeAA to propylimide Tensile tests

/department of chemical engineering and chemistry 21/24 Results (II)- Metal acetylacetonates Mechanism for coordination ATA-imide propylimide ATA-imide : 1eq Co >> 1eq Zn; 2 eq Zn ≈ 2 eq Co; 2 eq Zn > 1 eq Zn C 3 -imide : Co ≈ Zn; 1 eq > 2 eq

/department of chemical engineering and chemistry 22/24 Results (II)- Metal acetylacetonates Following mechanism was proposed to explain the results: In propylimide, Co and Zn can only weakly coordinate with O, leading to comparable properties In ATA-imide, additional strong coordination with N from the ATA-ring is possible. Two different situations: –Co likes to coordinate with N, so good properties are obtained for both low and high amounts –Zn likes to coordinate with O, so an excess of Zn has to be added to force strong coordination with N to get good properties. Conclusions

/department of chemical engineering and chemistry 23/24 Future work The effect of the tail length and the amount of the primary amines on the properties will be further investigated The influence of temperature and amount of octadecylamine on crystallization and mechanical properties will be studied Other systems of HB combined with ionic interactions will be prepared and evaluated, trying to avoid imide formation The exact coordination mechanism of MeAA modified MAn-g-EPM will be further investigated by EXAFS EXAFS can get information about coordination around metals Future work

/department of chemical engineering and chemistry 24/24 Acknowledgements Otto van Asselen Jules Kierkels All other colleagues of SKT Acknowledgement

/department of chemical engineering and chemistry 25/24 Structures and Names

/department of chemical engineering and chemistry 26/24 Mechanism of 4 fourfold coordination ATA-imide +1 eq CoAA ATA-imide +2 eq CoAA

/department of chemical engineering and chemistry 27/24 Mechanism of 4 fourfold coordination ATA-imide + 1 eq ZnAAATA-imide+ 2 eq ZnAA

/department of chemical engineering and chemistry 28/24 Future work