During the TANBCPdyes project, UV triggerable diblock copolymers (BCPs) have been synthesized in three steps via well-controlled RAFT polymerization and post-polymerization esterification reaction for application in inkjet printing. Poly(2-hydroxyethyl acrylate) macro-chain transfer agent with targeted degree of polymerization (Dp) 120 and 160 [macro-CTA1: P(HEA)120-CPDT; macro-CTA2: P(HEA)160-CPDT] were first synthesized via RAFT polymerization of 2-hydroxyethyl acrylate (HEA) in the presence of chain transfer agent cyano-2-propyl dodecyl trithiocarbonate (CPDT). The 1H NMR and GPC data confirm the successful synthesis of macro-CTA1 and macro-CT2. Then amphiphilic BCPs were synthesized by the chain extension of macro-CTA1 and macro-CTA2 with hydrophobic block derived from propyl methacrylate (PMA) monomer via RAFT polymerization in N,N-dimethyl formamide. The chain extension of macro-CTA1 and macro-CTA2 with second hydrophobic poly(PMA) block was achieved after 100 h polymerization of PMA. The % conversion of PMA, DP, the number average molecular weight (Mn), the average molecular weight (Mw) and Mw/Mn values confirm the synthesis of BCPs: Poly[(HEA)84-b-(PMA)11] and poly[(HEA)105-b-(PMA)12] via well-controlled RAFT polymerization.
Finally, UV-crosslinkable diblock copolymers have been created after post functionalization of amphiphilic BCPs with UV-triggerable cinnamic acid (CMA) by performing esterification at room temperature (RT). The post functionalization of BCPs with different amounts of UV-triggerable moiety was accomplished upon completion of esterification reaction within 72 h. UV-triggerable BCPs: CMA16-poly[(HEA)68-b-(PMA)11] and CMA27-poly[(HEA)78-b-(PMA)12] self-assembled in waterborne ethanol-water mixture (70:30 v/v). Unimodal particle size distribution was observed for 2 wt.% solution of UV-triggerable BCPs. Triggerable behaviour of BCPs was evaluated by UV-crosslinking thin films of CMA16-poly[(HEA)68-b-(PMA)11] and CMA27-poly[(HEA)78-b-(PMA)12] using a high intensity UV lamp. UV-triggerable BCPs are quickly crosslinked upon the exposure of UV light for a specific time. Only 3 to 5 minutes of exposure to UV light was found to be adequate for the crosslinking of both BCP thin films. The chemistry was then scaled up to produce these champion block copolymers in larger quantity. Samples of UV-triggerable BCPs (15 g in each case) have been supplied to Domino Printing Sciences (Cambridge, UK) for evaluating their printability and anchoring capability on hydrophobic substrates. It is noted that the study printability and anchoring capability of UV-triggerable BCPs is expected to be completed soon at Domino.
The results produced during the tenure of TANBCPdyes project would be exploited and disseminated through publications into the reputed journals as follows.
[1] M. Kumar, G. Maitland, M. Derry, J. J.L. Harries and P.D. Topham, Synthesis of UV-triggerable cinnamic acid functionalized diblock copolymers via controlled RAFT polymerization for ink-jet printing, Polymer Chemistry 2022 (Manuscript to be communicated soon).
[2] M. Kumar, J. Godlemann, M.J. Derry, J. J.L. Harries and P.D. Topham, Synthesis of Anthracene based UV triggerable block copolymers via controlled RAFT polymerization for ink-jet printing, Macromolecules, 2022 (Manuscript to be communicated soon).
