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Water-soluble polyisoprene polyrotaxanes based on cyclodextrins (CDs) were synthesized via rotaxa-polymerization for the first time in a single step in one pot. Hydrophilic β-CD derivatives were utilized to complex isoprene, which was copolymerized with bulky, hydrophilic comonomers that acted as stoppers. The effect of the CD derivatives, stoppers, initiators and monomer content on the yield, CD coverage, and solubility of the polymeric product were investigated. The best yield of water-soluble polymer was obtained for the stopper comonomer that consisted of poly(ethylene glycol) methyl ether methacrylate (PEG MA). The highest CD content (67 wt %) on the polyisoprene backbone was observed for randomly methylated β-CD (RAMEB) with a 1:1 molar ratio of isoprene to CD in the feed and for the thermal radical initiator VA-044. Excess isoprene over CD increases the yield of polyrotaxane but lowers its CD content and gives rise to partially insoluble byproducts. Polymer backbones (30 kDa) with high molar masses were achieved.

The aqueous reversible addition fragmentation chain-transfer (RAFT) copolymerization of isoprene and bulky comonomers, an acrylate and an acrylamide in the presence of methylated β-cyclodextrin was employed for the first time to synthesize block-copolyrotaxanes. RAFT polymerizations started from a symmetrical bifunctional trithiocarbonate and gave rise to triblock-copolymers where the outer polyacrylate/polyacrylamide blocks act as stoppers for the cyclodextrin rings threaded onto the inner polyisoprene block. Statistical copolyrotaxanes were synthesized by RAFT polymerization as well. RAFT polymerization conditions allow control of the composition as well as the sequence of the constituents of the polymer backbone which further effects the CD content and the aqueous solubility of the polyrotaxane.

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