In order to give an answer for the challenges of long
wavelength-photocontrolled
radical polymerization in aqueous solutions and to address the shortcomings
of conventional near-infrared (NIR) photocatalysts (PCs) that are
difficult to subject to post-treatment, we designed and synthesized
a series of β-tetra-substituted water-soluble zinc phthalocyanines
(β-TS-Zns) as the NIR PCs for reversible addition–fragmentation
chain transfer (RAFT) polymerization successfully under irradiation
with NIR (λmax = 730 nm) light at room temperature.
Importantly, the NIR PCs can also be designed as polymerizable monomers
and covalently loaded on the polymer chains, which are endowed with
permanent NIR photocatalysis of the resultant polymers. Moreover,
the polymerization can not only be carried out in water but also in
phosphate buffer saline (PBS) solution, yielding polymers with controlled
molar mass and narrow dispersities (Đ = 1.03–1.25).
Therefore, this NIR-photocontrolled aqueous RAFT polymerization system
may provide a charming strategy for possible applications in tissue
engineering biomaterial in situ benefiting from the high penetration
ability of NIR light.
Polymerization-induced self-assembly (PISA) has become an effective strategy to synthesize high solid content polymeric nanoparticles with various morphologies in situ. In this work, one-step PISA was achieved by in situ photocontrolled bromine-iodine transformation reversible-deactivation radical polymerization (hereinafter referred to as Photo-BIT-RDRP). The water-soluble macroinitiator precursor α-bromophenylacetate polyethylene glycol monomethyl ether ester (mPEG1k-BPA) was synthesized in advance, and then the polymer nanomicelles (mPEG1k-b-PBnMA and mPEG1k-b-PHPMA, where BnMA means benzyl methacrylate and HPMA is hydroxypropyl methacrylate) were successfully formed from a PISA process of hydrophobic monomer of BnMA or HPMA under irradiation with blue LED light at room temperature. In addition, the typical living features of the photocontrolled PISA process were confirmed by the linear increase of molecular weights of the resultant amphiphilic block copolymers with monomer conversions and narrow molecular weight distributions (Mw/Mn < 1.20). Importantly, the photocontrolled PISA process is realized by only one-step method by using in situ photo-BIT-RDRP, which avoids the use of transition metal catalysts in the traditional ATRP system, and simplifies the synthesis steps of nanomicelles. This strategy provides a promising pathway to solve the problem of active chain end (C-I) functionality loss in two-step polymerization of BIT-RDRP.
Grafting modification is a useful strategy to endow new functions to fluoropolymers with fluorinated backbone and expand their potential application fields. Herein, we reported a facile method to synthesize graft...
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