在这项工作中,梳型均聚物以及热响应性低聚(乙二醇甲醚甲基丙烯酸酯)的梳型共聚物,OEGMA,具有各种链长(DEGMA,PEGMA500和含有2、9或19个重复乙二醇单元的PEGMA950,分别)通过自由基(共)聚合合成。对于共聚物,功能性疏水甲基丙烯酸缩水甘油酯(GMA)或惰性亲水N,选择N-二甲基丙烯酰胺(DMAM)作为共聚单体。通过尼罗红荧光探测研究了产品的自组装和热响应行为,比浊法,和动态光散射(DLS)。有趣的是,发现所有基于OEGMA的均聚物在水性介质中都表现出自组织的趋势,除了热响应性。临界聚集浓度(CAC)随着OEGMA大分子单体中重复环氧乙烷单元的数量而增加(发现均聚物PDEGMA的CAC为0.003、0.01和0.03%w/v,分别为PPEGMA500和PPEGMA950)。此外,共聚物在水性介质中的CAC受到引入疏水性GMA或亲水性DMAM单元的高度影响,导致更低或更高的值,分别。因此,对于富含GMA的PEGMA950共聚物,CAC降低至0.003%w/v,而对于富含DMAM的DEGMA共聚物,CAC增加至0.01%w/v。比浊法和DLS研究证明,聚合物的热敏感性受几个参数控制,例如OEGMA侧链中重复乙二醇基团的数量,疏水或亲水共聚单体的摩尔百分比,以及在聚合物水溶液中添加盐。因此,发现均聚物PDEGMA的浊点为23°C,对于DMAM最富的DEGMA共聚物,浊点增加到33.5°C。最后,在加热含GMA的共聚物与二氧化硅纳米粒子的水性混合物过夜时形成水凝胶是这些聚合物的功能特性的有力证据。
In this work, comb homopolymers as well as comb-type copolymers of thermo-responsive oligo(ethylene glycol methyl ether methacrylate)s, OEGMAs, with various chain lengths (DEGMA, PEGMA500, and PEGMA950 containing 2, 9, or 19 repeating ethylene glycol units, respectively) were synthesized through free radical (co)polymerization. For the copolymers, either the functional hydrophobic glycidyl methacrylate (GMA) or the inert hydrophilic N,N-dimethylacrylamide (DMAM) were selected as comonomers. The self-assembly and thermo-responsive behavior of the products was investigated through Nile Red fluorescence probing, turbidimetry, and dynamic light scattering (DLS). Interestingly, it was found that all OEGMA-based homopolymers exhibit a tendency to self-organize in aqueous media, in addition to thermo-responsiveness. The critical aggregation concentration (CAC) increases with the number of repeating ethylene oxide units in the OEGMA macromonomers (CAC was found to be 0.003, 0.01, and 0.03% w/v for the homopolymers PDEGMA, PPEGMA500, and PPEGMA950, respectively). Moreover, the CAC of the copolymers in aqueous media is highly affected by the incorporation of hydrophobic GMA or hydrophilic DMAM units, leading to lower or higher values, respectively. Thus, the CAC decreases down to 0.003% w/v for the GMA-richest copolymer of PEGMA950, whereas CAC increases up to 0.01% w/v for the DMAM-richest copolymer of DEGMA. Turbidimetry and DLS studies proved that the thermo-sensitivity of the polymers is governed by several parameters such as the number of repeating ethylene glycol groups in the side chains of the OEGMAs, the molar percentage of the hydrophobic or hydrophilic comonomers, along with the addition of salts in the aqueous polymer solutions. Thus, the cloud point of the homopolymer PDEGMA was found at 23 °C and it increases to 33.5 °C for the DMAM-richest copolymer of DEGMA. Lastly, the formation of a hydrogel upon heating aqueous mixtures of the GMA-comprising copolymers with silica nanoparticles overnight is strong evidence of the functional character of these polymers.