Two-dimensional liquid chromatography of PDMS–PS block copolymers

Abstract

In this study, liquid chromatography at critical conditions of polystyrene (PS) and polydimethylsiloxane (PDMS) is used as the first dimension for the two-dimensional analysis of polydimethylsiloxane-block-polystyrene copolymers. Comprehensive two-dimensional liquid chromatography with size exclusion chromatography as the second dimension reveals information about the molar mass distributions of all separated fractions from the first dimension. Furthermore, fractions eluting at the critical conditions were collected and subjected to analysis in the second dimension at the critical adsorption point of the other block. These fractions were analyzed by Fourier transform infrared spectroscopy to determine their chemical compositions. The combination of the above approaches and the calibration of the evaporative light scattering detector for the first-dimension analysis yield deep insights into the molecular heterogeneity of the block copolymer samples. The composition of the samples and the chemical composition of the real block copolymer are also calculated by combining the results obtained at both critical conditions.

Synthesis and Characterization of Novel Biodegradable Di‐ and Tri‐Block Copolymers Based on Ethylene Carbonate Polymer as Hydrophobic Segment

“…[29][30][31][32] LCCC effectively allows separation of complex polymers with regard to distributions other than molar mass such as functionality, [29][30][31][32][36][37][38][39][40] and the other block. [24][25][26][27][28][29][30][31][32][33][34][35] In LCCC, exclusion and adsorption effects counterbalance each other, and critical homopolymers are transported along the column become 'chromatographically invisible', which means that their elution is no more dependent on the molar mass. Thus, in the case of a block copolymer, one block can be eluted under critical conditions while the other block can elute in either exclusion [28][29][30][31][32]36,49 or adsorption mode.…”

“…Molar mass of individual block, and absence or presence of unwanted homopolymers of both types is determined by liquid chromatography at critical conditions. Liquid chromatography at critical conditions has been used for analysis of the individual block lengths of the block copolymers, [24][25][26][27][28][29][30][31][32][33][34][35] and for end-group analysis of telechelics and functional polymers. [29][30][31][32][36][37][38][39][40] To the best of our knowledge, the novel block copolymers having PEEC as hydrophobic block are first time reported in this study.…”

Chromatographic characterization of amphiphilic di‐ and tri‐block copolymers of poly(ethylene oxide) and poly(ε‐caprolactone)

“…At this compensation point, termed as critical elution point, corresponding polymer becomes "chromatographically invisible", consequently all chains with the same end-functionality elute at same elution time regardless of their molar mass. Hence, separation with regard to other blocks [24][25][26][27][28][29][30][31][32][33][34][35] or end-functionality [36][37][38][39] can be achieved. LCCC has been successfully applied for quantification of critical homopolymers and fair estimation of a non-critical block length in the block copolymer [20,24,40].…”

Analysis of individual block length of amphiphilic di- & tri-block copolymers containing poly(ethylene oxide) and poly(methyl methacrylate)

“…Several different types of block copolymers have been synthesized and exploited for various applications, [26][27][28][29][30][31][32][33][34] however, the number of reports addressing analysis of individual block lengths and presence of unwanted homopolymers in the samples are rather limited. [35][36][37][38][39][40][41][42][43][44][45][46][47] Nonetheless, the length of individual blocks and presence of homopolymers in block copolymer sample can enormously affect the nal application properties, especially in case of amphiphilic block copolymers. The separation of homopolymers from amphiphilic block copolymer samples is a difficult task since products tend to make micelles when dropped in any solvent that has more compatibility for one block.…”

“…37,38 At critical conditions, homopolymers elute near the void volume of the column independent of their molar mass making them so called "chromatographically invisible". Under these conditions separation with regard to end group [61][62][63][64][65] or other block [35][36][37][38][39][40][41][42][43][44][45][46][47] can be realized. LCCC reveals a reasonable estimate of the molar mass distribution of non-critical block, and information with regard to presence or absence of unwanted parent homopolymers in the sample.…”