Preparation of multifunctional and well-defined macromolecules requires a smart selection of the most suitable controlled polymerization technique in combination with appropriate click reactions. In this review, we provide an overview on the use of various ''clickable'' initiators and monomers as well as on the postpolymerization modifications that have been widely used to construct clickable macromolecules. As such, this contribution will aid polymer chemists to select a suitable combination of CRP and click methodologies to design the target structures.

This feature article provides, for the first time, an overview of the research that guided the way from fundamental studies of the thermo-responsive phase separation of aqueous polymer solutions to polymeric sensor systems. The incorporation of solvatochromic dyes into thermoresponsive polymers as well as the concepts of polymeric sensors are presented and discussed in detail.

The interest in "smart" functional materials that respond to changes in the environment strongly increased in the last years owing to the desire to control complexity and to create systems that adapt or respond to the environment. Moreover, such "smart" materials are used to design and develop new responsive materials for a wide range of applications in various fields, such as biotechnology, [1][2][3] drug delivery, [4][5][6] particle transport, [7] and optical sensing. [8][9][10][11] Recently, a thermoresponsive fluorescent nanogel was applied as an intracellular thermometer, that is, to monitor the temperature in living cells. [12] A current trend in the field of optical sensing is the development of dual sensors that respond simultaneously and independently to different stimuli. [13] In recent years, dual optical sensors have been reported for pressure and temperature, [14] oxygen and temperature, [15][16][17][18] oxygen and carbon dioxide, [19][20][21] as well as oxygen and pH value. [22][23][24] Surprisingly, no dual sensor has been reported for temperature and pH value, which would be beneficial, for example to monitor chemical reactions and for biological diagnostics.We have aimed to develop a soluble dual sensor that responds to both temperature and pH value. The solubility of the sensor material allows monitoring in situ while at the same time providing information about homogeneity and local conditions. In contrast to reported dual sensors, which are generally based on two different sensing chromophores, we have combined a pH-responsive solvatochromic dye with a thermoresponsive polymer. Solvatochromic dyes change color in response to changes in solvent polarity. [25][26][27] Recently, it was reported that combining a solvatochromic dye with a temperature-responsive polymer leads to a color change upon changing the temperature, as in the dissolved state the dye is in contact with water while in the collapsed state the dye is dissolved in the less polar precipitated polymer. [8][9][10]12] Herein, we report our efforts to develop a dual sensor that senses temperature by the solubility transition of a thermoresponsive polymer and senses the pH value by a pHresponsive solvatochromic dye, namely disperse red 1 (DR1, 1; Scheme 1). [28,29] Poly(oligoethyleneglycol methacrylate) (POEGMA) was chosen as temperature sensing polymer on the basis of its biocompatibility and the possibility of tuning the lower critical solution temperature (LCST) by copolymerizing different OEGMA monomers. [30][31][32] Since the polymer solubility transition can depend on the molar mass distribution of the copolymer, a well-defined polymer is required to ensure homogeneous solubility of the sensing polymer. Therefore, a controlled radical polymerization process, namely reversible addition fragmentation chain transfer (RAFT), [33][34][35] was applied to prepare welldefined copolymers of OEGMA and a methacrylate monomer functionalized with disperse red 1 (DR1-MA, 3; Scheme 1).For this purpose monomer 3 was prepared by esterification of...