Synthesis of Amphiphilic Helix–Coil–Helix Poly(3-(glycerylthio)propyl isocyanate)-<i>block</i>-polystyrene-<i>block</i>-poly(3-(glycerylthio)propyl isocyanate)

To achieve molecular packing of protic-functionalized helical polymers in aqueous solution, we synthesized an amphiphilic helix–coil–helix triblock copolymer (triBCP) composed of polystyrene and dihydroxyl-functionalized polyisocyanates. Poly­(3-(glycerylthio)­propyl isocyanate)-<i>block</i>-polystyrene-<i>block</i>-poly­(3-(glycerylthio)­propyl isocyanate), P3GPIC-<i>b</i>-PSt-<i>b</i>-P3GPIC, was synthesized by postpolymerization modification. The bidirectional anionic block copolymerization of styrene (St) and allyl isocyanate (AIC) yielded triBCPs, poly­(allyl isocyanate)-<i>block</i>-polystyrene-<i>block</i>-poly­(allyl isocyanate)­s (PAIC-<i>b</i>-PSt-<i>b</i>-PAICs), with well-controlled molecular weights (<i>M</i>_n = 5.60–99.9 kDa) and narrow dispersities (<i>Đ</i> = 1.14–1.18). Of them, one with the lowest MW (<i>M</i>_n = 5.60 kDa, <i>Đ</i> = 1.14), which was highly organic-soluble, was utilized in the thiol–ene click reaction between allyl group and 1-thioglycerol, producing P3GPIC-<i>b</i>-PSt-<i>b</i>-P3GPIC. The amphiphilic P3GPIC-<i>b</i>-PSt-<i>b</i>-P3GPIC self-aggregated to form spherical vesicles with an average hydrodynamic diameter of 170 nm in aqueous solution, demonstrating that hydrophilic–helical P3GPIC blocks well interacted with water media maintaining their intermolecular packing

Synthesis of Novel Amphiphilic Polyisocyanate Block Copolymer with Hydroxyl Side Group

A novel amphiphilic polyisocyanate block copolymer with hydroxyl side groups was synthesized by a combination of living anionic polymerization and thiol–ene click chemistry. First, the living anionic block copolymerization of allyl isocyanate (AIC) and <i>n</i>-hexyl isocyanate (HIC) produced a well-defined block copolymer (PAIC-<i>b</i>-PHIC) as a precursor. The subsequent free-radical-mediated thiol–ene click reaction of this polymer with 2-mercaptoethanol at room temperature quantitatively converted the allyl side groups of the PAIC domain to hydroxyl groups, finally creating PAIC­(OH)-<i>b</i>-PHIC. The amphiphilicity of PAIC­(OH)-<i>b</i>-PHIC led to lamellar and cylindrical phase separations in the thin films cast from different solvents (THF and toluene). The functionalities and phase separation behaviors of PAIC­(OH)-<i>b</i>-PHIC were characterized by NMR, SEC-MALLS, and TEM analysis

Experimental Formulation of Photonic Crystal Properties for Hierarchically Self-Assembled POSS–Bottlebrush Block Copolymers

Rodlike “POSS–bottlebrush block copolymers” (POSSBBCPs) containing crystalline polyhedral oligomeric silsesquioxane (POSS) pendants in A block and amorphous polymeric grafts in B block were utilized to create one-dimensional (1D) photonic crystals (PCs). 3-(12-(<i>cis</i>-5-Norbornene-<i>exo</i>-2,3-dicarboximido)­dodecanoylamino)­propyl­heptaisobutyl POSS (<b>NB-A16-POSS</b>, M_A) and <i>exo</i>-5-norbornene-2-carbonyl-end poly­(benzyl methacrylate) (<b>NBPBzMA</b>, M_B) were employed in sequential ring-opening metathesis polymerization to afford poly­[3-(12-(<i>cis</i>-5-norbornene-<i>exo</i>-2,3-dicarboximido)­dodecanoylamino)­propyl­heptaisobutyl POSS]-<i>block</i>-poly­(<i>exo</i>-5-norbornene-2-carbonylate-<i>graft</i>-benzyl methacrylate)­s, <b>P­(NB-A16-POSS)-</b><i><b>b</b></i><b>-P­(NB-</b><i><b>g</b></i><b>-BzMA)</b>s, with well-modulated block compositions (<i>f</i>_A = 34, 50, and 67 wt %) and overall degrees of polymerization (DP = 323–939). The <b>P­(NB-A16-POSS)-</b><i><b>b</b></i><b>-P­(NB-</b><i><b>g</b></i><b>-BzMA)</b>s hierarchically self-assembled to form highly ordered 1D PC films with periodic lamellar arrays that can reflect visible light with particular wavelengths. Their reflectance bandwidths, reflectivities, and ranges of peak reflectance wavelnegth (λ_peak) were largely dependent on the block composition. The 1D PC films based on lamellar <b>P­(NB-A16-POSS)-</b><i><b>b</b></i><b>-P­(NB-</b><i><b>g</b></i><b>-BzMA)</b>s demonstrated the capability of formaulation of λ_peak as linear functions of initial polymerization parameter ([M]₀/[I]₀)

Precise Synthesis of Bottlebrush Block Copolymers from ω‑End-Norbornyl Polystyrene and Poly(4-<i>tert</i>-butoxystyrene) via Living Anionic Polymerization and Ring-Opening Metathesis Polymerization

A facile and efficient synthetic grafting-through strategy for preparing well-defined bottlebrush block copolymers (BBCPs) was developed through a combination of living anionic polymerization (LAP) and ring-opening metathesis polymerization (ROMP). ω-End-norbornyl polystyrene (NPSt) and poly­(4-<i>tert</i>-butoxystyrene) (NP<i>t</i>BOS) were synthesized by LAP using terminator of chlorine moiety containing silane-protecting amine and coupled with a subsequent amidation using norbornyl activated ester. Bottlebrush homopolymers of NPSt were obtained by ROMP with ultrahigh molecular weights (MWs, <i>M</i>_w = 2928 kDa) and narrow molecular weight distributions (MWDs, <i>Đ</i> = 1.07) at high degree of polymerizations (DP_w = 1084). Well-defined BBCPs with ultrahigh MWs (<i>M</i>_w ∼ 3055 kDa) and narrow MWDs (<i>Đ</i> ∼ 1.13) were synthesized through sequential ROMP of NPSt with NP<i>t</i>BOS. The effect of ultrahigh MWs was investigated by self-assembly of the BBCPs in which the phase-separated BBCPs presented periodic lamellar structures and exhibited structural colors from blue to pink

A Model Chiral Graft Copolymer Demonstrates Evidence of the Transmission of Stereochemical Information from the Side Chain to the Main Chain on a Nanometer Scale

A model chiral graft copolymer, poly­(phenylacetylene)-<i>g</i>-poly­(<i>n</i>-hexyl isocyanate) (PPA-<i>g</i>-PHIC), in which a chiral moiety is located at the end of each PHIC side chain, was synthesized. First, chiral PHIC macromonomers with a phenylacetylene end group were synthesized via living anionic polymerization using the functional initiator sodium <i>N</i>-(4-ethynylphenyl)­benzamide (Na-4EPBA) and then end-capped using the chiral terminator (<i>S</i>)-2-acetoxypropionyl chloride ((<i>S</i>)-C<i>t</i>). The molecular weights (MWs) of the PHIC macromonomers were controlled based on the feed ratio of the monomer to the initiator. Subsequent polymerization of PHIC macromonomers using Rh⁺(2,5-norbornadiene)­[(η⁶-C₆H₅)­B^–(C₆H₅)₃] (Rh­(nbd)­BPh₄) catalyst generated chiral PPA-<i>g</i>-PHIC graft copolymers with varying graft strand lengths. Chiral macromonomers and graft copolymers were characterized by SEC-MALLS, NMR, and CD spectroscopy. This model chiral graft copolymer provided an excellent example of the transmission of stereochemical information from the side chain to the main chain, as a preferred helicity was induced in the PPA backbone of the graft copolymer even when chiral moieties were separated from the main chain by nanometer scale distances (5.4–13 nm). Furthermore, CD spectroscopy clearly showed that the CD intensity of the PPA main chain was directly dependent on the CD intensity of the optically active PHIC side chain determined by the strand length

Synthesis of Hard–Soft–Hard Triblock Copolymers, Poly(2-naphthyl glycidyl ether)-<i>block</i>-poly[2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether]-<i>block</i>-poly(2-naphthyl glycidyl ether), for Solid Electrolytes

Hard–soft–hard triblock copolymers based on poly­(ethylene oxide) (PEO), poly­(2-naphthyl glycidyl ether)-<i>block</i>-poly­[2-(2-(2-methoxy­ethoxy)­ethoxy)­ethyl glycidyl ether]-<i>block</i>-poly­(2-naphthyl glycidyl ether)­s (PNG-PTG-PNGs), were synthesized by sequential ring-opening polymerization of 2-(2-(2-methoxy­ethoxy)­ethoxy)­ethyl glycidyl ether and 2-naphthyl glycidyl ether using a bidirectional initiator catalyzed by a phosphazene base. Four PNG-PTG-PNGs had different block compositions (<i>f</i>_wt,PNG = 9.2–28.6 wt %), controlled molecular weights (<i>M</i>_n = 23.9–30.9 kDa), and narrow dispersities (<i>Đ</i> = 1.11–1.14). Most of the PNG-PTG-PNG electrolytes had much higher Li⁺ conductivities than that of a PEO electrolyte (6.54 × 10^–7 S cm^–1) at room temperature. Eespecially, the Li⁺ conductivity of PNG₁₈-PTG₁₀₇-PNG₁₈ electrolyte (9.5 × 10^–5 S cm^–1 for <i>f</i>_wt,PNG = 28.6 wt %) was comparable to one of a PTG electrolyte (1.11 × 10^–4 S cm^–1). The Li⁺ conductivities of PNG-PTG-PNG electrolytes were closely correlated to efficient Li⁺ transport channels formed by the microphase separation into soft PTG and hard PNG domains