About the phase transitions in aqueous solutions of thermoresponsive copolymers and hydrogels based on 2-(2-methoxyethoxy)ethyl methacrylate and oligo(ethylene glycol) methacrylate
About the phase transitions in aqueous solutions of thermoresponsive copolymers and hydrogels based on 2-(2-methoxyethoxy)ethyl methacrylate and oligo(ethylene glycol) methacrylate
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DOI：
10.1021/ma062925q
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发表时间：
2007-04-03
期刊：
影响因子：
5.5
通讯作者：
Hoth, Ann
中科院分区：
文献类型：
--
作者：
Lutz, Jean-Francois;Weichenhan, Katja;Hoth, Ann
用1H NMR、动态光散射和比浊法研究了甲基丙烯酸2-（2-甲氧基乙氧基）乙酯（MEO（2）MA）和低聚乙二醇甲基丙烯酸酯（OEGMA，Mn = 475 gmol（-1））共聚物在水中的相变。这些共聚物是通过原子转移自由基聚合（ATRP）合成的，以获得具有均匀的链-链共聚单体组成的大分子，因此具有窄的相变。如前所述，每个链含有10摩尔%OEGMA的共聚物（M-n = 20 × 100 g mol（-1 ;）M-w/M-n = 1.35）在40 ℃左右的水中表现出急剧的LCST，而每条链具有20 mol %OEGMA的共聚物在40 ℃左右的水中表现出急剧的LCST，（M-n = 19 500 g mol（-1）; M-w/M-n = 1.32）在略高于50 ℃时沉淀。DLS表明，这些相变很可能是由于可逆的线圈到球的转变。此外，在交联剂二甲基丙烯酸乙二醇酯的存在下，通过ATRP合成了MEO（2）MA和OEGMA的共价交联网络。这些水凝胶是温敏性的，并表现出与其单链类似物（例如，在网络内含有20摩尔%OEGMA的水凝胶在约51-53 ℃下经历相变）。
The phase transitions in water of well-defined copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO(2)MA) and oligo(ethylene glycol) methacrylate (OEGMA, M-n = 475 g mol(-1)) were studied by means of H-1 NMR, dynamic light scattering (DLS) and turbidimetry. These copolymers were synthesized by atom transfer radical polymerization (ATRP) in order to obtain macromolecules with a homogeneous chain-to-chain comonomer composition and therefore with a narrow phase transition. As previously reported, copolymers containing 10 mol % of OEGMA per chain (M-n = 20 100 g mol(-1 ;) M-w/M-n = 1.35) exhibited a sharp LCST in water around 40 degrees C, whereas copolymers having 20 mol % of OEGMA per chain (M-n = 19 500 g mol(-1); M-w/M-n = 1.32) precipitated slightly above 50 degrees C. DLS indicated that these phase transitions are most likely due to a reversible coil-to-globule transition. Moreover covalently cross-linked networks of MEO(2)MA and OEGMA were synthesized by ATRP in the presence of the cross-linker ethylene glycol dimethacrylate. These hydrogels were thermoresponsive and exhibited LCST values comparable to those measured for their single-chains analogues (e.g., hydrogels containing 20 mol % of OEGMA within the network underwent phase transitions at approximately 51-53 degrees C).