Two methodologies for synthesizing novel, degradable, core cross-linked copolymer particles were investigated and the molecular properties of the resultant polymers were compared. The first approach was to synthesize hyperbranched poly(ε-caprolactone-co-N,N-dimethylamino-2-ethyl methacrylate (PCL-co-PDMAEMA) by combining metal-catalyzed ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) and reversible addition−fragmentation chain transfer polymerization (RAFT) of N,N-dimethylamino-2-ethyl methacrylate. First, the hyperbranched core was prepared via ROP copolymerization of ε-CL and branching agent 4,4-bioxepanyl-7,7-dione (BOD). This polymerization was initiated using the hydroxyl moiety of the bifunctional initiator 4-cyano-1-hydroxypent-4-yl dithiobenzoate (ACP-RAFT) which resulted in reactive pendent RAFT groups located on the polymer chains. The hyperbranched structure was confirmed by GPC-MALLS and NMR. Subsequent chain extension of this hyperbranched macromolecule with DMAEMA using RAFT chemistry yielded water-soluble nanoparticles. The second method involved the synthesis of core-cross-linked-shell particles (CCS) by the arm-first route. Linear arms of DMAEMA were synthesized using ACP-RAFT and subsequently used as macroinitiator for the ROP of ε-CL and BOD to form a degradable microgel that was water-soluble. Once again, molecular structure was analyzed by ¹H NMR, ¹³C NMR, and GPC and molecular size by TEM. Finally, GPC-MALLS was used to qualitatively investigate the different cross-link densities of the degradable core by the two different methodologies. Thus, we demonstrate two synthetic approaches for constructing water-soluble, degradable core−shell nanoparticles that exhibit varying degrees of cross-linking by combining RAFT and ROP.

中文翻译：

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通过RAFT和ROP可生物降解的核壳材料：超支化和微凝胶颗粒的表征和比较

研究了两种合成新型可降解核交联共聚物颗粒的方法，并比较了所得聚合物的分子性质。第一种方法是，以合成超支化聚（ε-己内酯共- Ñ，ñ -二甲基氨基-2-乙基甲基丙烯酸酯（PCL- CO -PDMAEMA）通过组合ε己内酯的金属催化的开环聚合（ROP）（ε -CL）和N，N的可逆加成-断裂链转移聚合（RAFT）-甲基丙烯酸二甲氨基-2-乙酯。首先，通过ε-CL和支化剂4,4-bioxepanyl-7,7-dione（BOD）的ROP共聚制备超支化核。使用双官能引发剂4-氰基-1-羟基戊-4-基二硫代苯甲酸酯的羟基部分（ACP-RAFT）引发该聚合反应，这导致了位于聚合物链上的反应性侧基RAFT基团。通过GPC-MALLS和NMR确认了超支化结构。随后使用RAFT化学方法用DMAEMA对该超支化大分子进行链扩展，产生了水溶性纳米粒子。第二种方法涉及通过手臂优先路线合成核交联壳颗粒（CCS）。使用ACP-RAFT合成DMAEMA的线性臂，然后将其用作ε-CL和BOD的ROP的大分子引发剂，以形成水溶性的可降解微凝胶。再次，通过¹ H NMR，¹³ C NMR和GPC以及通过TEM的分子大小。最后，使用GPC-MALLS通过两种不同的方法定性研究可降解核芯的不同交联密度。因此，我们展示了两种合成方法，可用于构建水溶性，可降解的核壳纳米粒子，这些纳米粒子通过结合RAFT和ROP表现出不同程度的交联。