Well-defined ABA- and BAB-type block copolymers of PDMAEMA and PCL

Triblock copolymers of ABA- and BAB-type consisting of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, A) and poly(epsilon-caprolactone) (PCL, B) have successfully been prepared. PDMAEMA-b-PCL-b-PDMAEMA (ABA) and PCL-b-PDMAEMA-b-PCL (BAB) were synthesised by a combination of ring-opening polymerisation of epsilon-CL, atom transfer radical polymerisation of DMAEMA and end-group conversion, performed through either acylation or azide-alkyne "click" chemistry. All samples were analysed by size exclusion chromatography where it was found that the evaluation of PDMAEMA-containing polymers was difficult due to the thermoresponsivity of PDMAEMA, affecting the solubility of the polymer in the temperature range at which the SEC was operated. From differential scanning calorimetry measurements it was shown that the crystallinity could be altered by changing the order of the blocks; with PDMAEMA as the outer block (ABA), the inherent crystallinity of PCL was destroyed while with PCL as the outer block (BAB), the degree of crystallinity was in the same proximity as for a PCL homopolymer.