Koler Amadeja, Brus Jiři, Krajnc Peter
PolyOrgLab, Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia.
Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského náměstí 2, 16200 Prague, Czech Republic.
Polymers (Basel). 2023 May 10;15(10):2255. doi: 10.3390/polym15102255.
The influence of a polymerisation mechanism (reversible addition-fragmentation chain transfer; RAFT vs. free radical polymerisation; FRP) on the porous structure of highly porous poly(styrene-co-divinylbenzene) polymers was investigated. The highly porous polymers were synthesised via high internal phase emulsion templating (polymerizing the continuous phase of a high internal phase emulsion), utilising either FRP or RAFT processes. Furthermore, residual vinyl groups in the polymer chains were used for the subsequent crosslinking (hypercrosslinking) applying di-tert-butyl peroxide as the source of radicals. A significant difference in the specific surface area of polymers prepared by FRP (between 20 and 35 m/g) and samples prepared by RAFT polymerisation (between 60 and 150 m/g) was found. Based on the results from gas adsorption and solid state NMR, it could be concluded that the RAFT polymerisation affects the homogeneous distribution of the crosslinks in the highly crosslinked styrene-co-divinylbenzene polymer network. During the initial crosslinking, RAFT polymerisation leads to the increase in mesopores with diameters between 2 and 20 nm, resulting in good accessibility of polymer chains during the hypercrosslinking reaction, which is reflected in increased microporosity. The fraction of micropores created during the hypercrosslinking of polymers prepared via RAFT is around 10% of the total pore volume, which is up to 10 times more than for polymers prepared by FRP. Specific surface area, mesopore surface area, and total pore volume after hypercrosslinking reach almost the same values, regardless of the initial crosslinking. The degree of hypercrosslinking was confirmed by determination of the remaining double bonds by solid-state NMR analysis.
研究了聚合机理（可逆加成-断裂链转移；RAFT与自由基聚合；FRP）对高孔隙率聚（苯乙烯-共-二乙烯基苯）聚合物多孔结构的影响。通过高内相乳液模板法（聚合高内相乳液的连续相）合成高孔隙率聚合物，采用FRP或RAFT工艺。此外，聚合物链中的残留乙烯基用于后续交联（超交联），以二叔丁基过氧化物作为自由基源。发现通过FRP制备的聚合物（20至35 m²/g之间）和通过RAFT聚合制备的样品（60至150 m²/g之间）的比表面积存在显著差异。基于气体吸附和固态NMR的结果，可以得出结论，RAFT聚合影响高度交联的苯乙烯-共-二乙烯基苯聚合物网络中交联的均匀分布。在初始交联过程中，RAFT聚合导致直径在2至20 nm之间的中孔增加，从而在超交联反应期间聚合物链具有良好的可及性，这反映在微孔率增加上。通过RAFT制备的聚合物在超交联过程中产生的微孔分数约为总孔体积的10%，这比通过FRP制备的聚合物高出多达10倍。无论初始交联如何，超交联后的比表面积、中孔表面积和总孔体积几乎达到相同的值。通过固态NMR分析测定剩余双键来确认超交联程度。
