Preparation of a novel polymer monolith with high loading capacity by grafting block poly(PEGA–mPEGA) for high-efficiency solid phase synthesis

The polymer monolith for solid-phase synthesis with high efficiency was prepared through in situ copolymerization of chloromethylstyrene and ethylene glycol dimethacrylate (PCMS–EDMA). The obtained monolith was grafted by two kinds of poly(ethylene glycol) acrylate oligomer, poly(ethylene glycol) acrylate (PEGA) and poly(ethylene glycol) methyl ether acrylate (mPEGA). The monolith was grafted via activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) with the increased number of functional groups (–OH). About 0.61–0.81mmol/g hydroxyl group resulted from side groups in each grafting polymer chain. PmPEGA in the grafting block copolymer chains can increase the distance between the adjacent reactive sites of PEGA (–OH) in each polymer chain. Therefore, the grafted monoliths with the block copolymer of PEGA-co-mPEGA can give high yield (85%) and purity (93%) of the crude peptide (a difficult sequence-acyl carrier protein fragment 65–74) under the condition of high loading capacity (0.76mmol/g). These results were higher than those by the grafted monolith with only polymer of PEGA (72% and 81%, respectively) and commercial Wang resin (43% and 39%, respectively). The synthetic efficiency on the grafted monolith with block copolymer in the continuous flow technique was 5–6 folds higher than Wang resins in the manual operation conditions.