The thermoresponsive behavior of a poly(2-oxazoline)-based molecular brush is investigated in aqueous solution. The molecular brush under study, PiPOx100-g-PEtOx17, has a poly(2-isopropenyl-2-oxazoline) (PiPOx) backbone grafted with thermoresponsive poly(2-ethyl-2-oxazoline) (PEtOx) side chains. Since the backbone degree of polymerization is only a factor of ~ 6 higher than the ones of the side chains, it features an architecture between a star-like polymer and a comb-like polymer. Its aqueous solution exhibits lower critical solution temperature (LCST) behavior with a cloud point temperature Tcp = 40.5 °C at 30 g L−1. The temperature-dependent structural evolution is disclosed using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). An increase of the molecular brush size is found upon heating from room temperature to Tcp, which is attributed to the extension of the backbone resulting from the dehydration and collapse of the side chains. Above Tcp, the size decreases again, which indicates the collapse of the whole molecular brush. Large aggregates are found to be present in the solution in the temperature range 25–50 °C. These become more compact, as the temperature is increased across Tcp. Graphical abstract Transmission and scattering intensity in relation to temperature and momentum transfer, respectively Transmission and scattering intensity in relation to temperature and momentum transfer, respectively

中文翻译：

---

具有热响应聚（2-乙基-2-恶唑啉）侧链的分子刷：结构研究

在水溶液中研究了基于聚 (2-恶唑啉) 的分子刷的热响应行为。正在研究的分子刷 PiPOx100-g-PEtOx17 具有接枝有热响应聚（2-乙基-2-恶唑啉）（PEtOx）侧链的聚（2-异丙烯基-2-恶唑啉）（PiPOx）主链。由于主链聚合度仅比侧链聚合度高约 6 倍，因此它具有介于星状聚合物和梳状聚合物之间的结构。它的水溶液表现出较低的临界溶解温度 (LCST) 行为，在 30 g L−1 时浊点温度 Tcp = 40.5 °C。使用动态光散射 (DLS) 和小角度中子散射 (SANS) 公开了与温度相关的结构演变。从室温加热到 Tcp 时发现分子刷尺寸增加，这归因于侧链的脱水和塌陷导致主链的延伸。在 Tcp 之上，尺寸再次减小，这表明整个分子刷坍塌。发现在 25-50 °C 的温度范围内溶液中存在大的聚集体。随着跨 Tcp 的温度升高，这些变得更加紧凑。分别与温度和动量传递相关的图形抽象传输和散射强度，分别与温度和动量传递相关的传输和散射强度 发现在 25-50 °C 的温度范围内溶液中存在大的聚集体。随着跨 Tcp 的温度升高，这些变得更加紧凑。分别与温度和动量传递相关的图形抽象传输和散射强度，分别与温度和动量传递相关的传输和散射强度 发现在 25-50 °C 的温度范围内溶液中存在大的聚集体。随着跨 Tcp 的温度升高，这些变得更加紧凑。分别与温度和动量传递相关的图形抽象传输和散射强度，分别与温度和动量传递相关的传输和散射强度