Co-Polyoxetanes with Alkylammonium and Fluorous or PEG-Like Side Chains:  Soft Blocks for Surface Modifying Polyurethanes

Abstract

The goal of this work was to prepare polyurethanes having P[AB] co-polyoxetane soft blocks, where A is a surface active (fluorous) or PEG-like side chain and B represents a desired function (alkylammonium). To this end, poly(2,2-substituted-1,3-propylene oxide) ran-co-telechelics with bromobutoxymethyl (-CH 2 O(CH 2 ) 4 -Br) and either trifluoroethoxymethyl (3FOx, -CH 2 OCH 2 CF 3 )) or PEG-like (2-(2-methoxyethoxy)ethoxy)methyl (ME2Ox, (-CH 2 (OCH 2 CH 2 ) 2 OCH 3 )) side chains were prepared via cationic ring-opening polymerization. Characterization utilized 1 H NMR spectroscopy, temperature modulated differential scanning calorimetry (MDSC) and thermogravimetric analysis (TGA). Molecular weights (M n ) by 1 H NMR end group analysis were ∼6 kDa while bromobutoxymethyl co-telechelic T g s were -68 and -48°C for ME2Ox and 3FOx, respectively. Bromobutoxymethyl groups were completely substituted with N,N-dimethylalkyl amines to obtain oxetane B repeats with six carbon (C6) and twelve carbon (C12) alkylammonium side chains. P[AB] T g s remained low after amine substitution. Co-telechelics were incorporated into polyurethanes (PUs) having 4,4′-(methylene bis (p-cyclohexyl isocyanate) (H 12 MDI) and butanediol (BD) as the hard block (30 wt %). Characterization by 1 H NMR, GPC, MDSC, and TGA is described. From DSC data, using the Fox equation, the weight fraction of pure soft block in the soft block domain (w 1 ) was very high (0.96-0.99) for polyurethanes with fluorous soft blocks, while soft blocks with PEG-like side chains were phase mixed (w 1 ) 0.73-0.75). To our knowledge, this is the first time that a polycationic telechelic has been incorporated in a polyurethane. TGA in nitrogen confirmed stoichiometry and showed that both alkylammonium co-telechelics and polyurethanes had good thermal stability.

Synthesis, Properties, and Applications of Ion‐Containing Polyurethane Segmented Copolymers

“…As a result, the synthesis of segmented polyurethanes with charge specifically in the SS requires novel oligomers. Despite the synthetic challenges, several ion‐containing SSs exist as a result of the efforts of many research groups . Ammonium, sulfonate, and carboxylate‐containing SSs were prepared, providing similar ionic variety as charged HS monomers.…”

“…The location and amount of ionic groups within the SS, and ultimately in the resulting segmented polyurethane, depend on the synthesis of the SS. Kurt et al synthesized alkyl bromide‐containing poly(oxetanes), which was amenable to a quantitative substitution reaction to afford pendant ammonium groups. A transesterification reaction of PEG with dimethyl 5‐sulfoisophthalate sodium salt resulted in a sulfonated SS with only one ionic group per SS unit .…”

“…A transesterification reaction of PEG with dimethyl 5‐sulfoisophthalate sodium salt resulted in a sulfonated SS with only one ionic group per SS unit . Figure depicts the chemical structures of some commercially available ( F , G , and I ) and ion‐containing SSs ( H and J ), showing the variation in ion placement . Throughout this review, many other ion‐containing SSs including the effect of ionic content and placement on polymer properties will be discussed.…”

“…Despite the synthetic challenges, several ion-containing SSs exist as a result of the efforts of many research groups. [ 27,31,[38][39][40][41][42][43][44][45] Ammonium, sulfonate, and carboxylate-containing SSs were prepared, providing similar ionic variety as charged HS monomers. The location and amount of ionic groups within the SS, and ultimately in the resulting segmented polyurethane, depend on the synthesis of the SS.…”

Nanoscale versus Microscale Gelation for Crosslinked Polyurethanes

“…In polyurethanes and similar hard‐block/soft‐block systems, soft blocks preferentially occupy this interface 1–7. Given the thermodynamic driving force for soft block surface concentration, we have explored surface modification using soft blocks that surface concentrate a desired function 8–11. Our strategy for generating coatings with functional surfaces is directed at novel soft blocks with functionalized side chains.…”