A Sophisticated Resin for the Solution of Synthesis Challenges. TentaGel® XV resin (XV stands for "Extended Swelling Volume") is a new member of the TentaGel® family. Modifications on the polystyrene backbone change the swelling properties of the PEG grafted resin. Swelling properties are in the same range or even higher compared to PEGA or Chematrix resins. The polar PEG spacers allow the composite resin to swell in a wide range of solvents including water, methanol, DMF, DCM. Nevertheless, the handling is still very easy and similar to other TentaGel® resins. The high swelling creates an extended reaction space. This enlarged reaction volume meets the requirement for ideal conditions for the synthesis of difficult sequences, aggregating peptides, mini proteins and PNAs in high purities and excellent yields. Purified yield of PNA4-peptide15-PNA11 Resin yield [%] Wang resin 0 Chematrix 20 TentaGel® XV 31 This resin is recommended for synthesis of difficult peptide sequences and long peptide acids. The resin is functionalized with the acid labile HMPA linker. Cleavage from this support is achieved by 95% TFA and gives peptide acids.